Biomedical subjects

T Kitazawa

Publications and source records attributed to T Kitazawa.

At least 37 records · Page 2Linked to original sources

PubMed2000

Hapten-specific tolerance promoted by calcitonin gene-related peptide.

Calcitonin gene-related peptide has been shown to modulate inflammatory and immune responses in various systems. Recent studies in our laboratory and colleagues have shown that intracutaneously injected calcitonin gene-related peptide impairs the induction of contact hypersensitivity in mice, and participates in the pathogenesis of failed contact hypersensitivity induction after acute, low-dose ultraviolet B radiation. In this study we investigated the ability of calcitonin gene-related peptide to induce tolerance in normal and mast cell deficient mice and we examined the extent to which calcitonin gene-related peptide contributes to the tolerance induced by acute, low-dose ultraviolet B radiation. Calcitonin gene-related peptide was injected intradermally followed by application of 2,4-dinitro-1-fluorobenzene to the injected skin surface. Tolerance was assessed by re-exposing the mice 2 wk later to a second, sensitizing dose of 2, 4-dinitro-1-fluorobenzene on uninjected skin. We found that calcitonin gene-related peptide induced tolerance to 2, 4-dinitro-1-fluorobenzene in both normal and mast cell deficient mice. Calcitonin gene-related peptide-induced tolerance was blocked by intradermal injection of a calcitonin gene-related peptide antagonist [CGRP-(8-37)] that selectively blocks the calcitonin gene-related peptide receptor. Tolerance was also abolished by intraperitoneally injected anti-interleukin-10, but not anti-tumor necrosis factor alpha, antibodies. When 2,4-dinitro-1-fluorobenzene was painted on skin into which splenic dendritic cells pretreated with calcitonin gene-related peptide had been injected, tolerance was observed. Calcitonin gene-related peptide- treated dendritic cells mixed with anti-interleukin-10 antibody prior to intradermal injection failed to promote tolerance. Finally, injection of CGRP-(8-37) into skin that was subsequently exposed to acute, low-dose ultraviolet B radiation partially prevented tolerance induced by local application of 2,4-dinitro-1-fluorobenzene. These results indicate that calcitonin gene-related peptide has the capacity to promote cutaneous tolerance through an interleukin-10-dependent mechanism. This mechanism, which does not require the participation of mast cells, contributes to the tolerance promoted by acute, low-dose ultraviolet B radiation. Thus, calcitonin gene-related peptide from cutaneous nerve endings plays a key role in the local immune aberrations caused by ultraviolet B radiation.

Animals↗

PubMed2000

Functional lip reconstruction with a radial forearm free flap combined with a masseter muscle transfer after wide total excision of the chin.

Total lower lip reconstruction was accomplished by combining a radial forearm free flap with a masseter muscle transfer. The patient, who had T4 carcinoma, had the entire lower lip resected including the depressor anguli oris muscle. A radial forearm flap was used to reconstruct the lower lip lining and the floor of the oral cavity. The right and left masseter musculofascial flaps were elevated and transferred in the medial-superior direction, and the peripheral margins of the flaps were sutured together. The lateral margins of the flaps were then sutured to the orbicularis oris muscle of the upper lip. Good sphincter function was obtained more than 1 year after the operation, electromyography revealed almost normal mobility of the transferred masseter muscles, and no sagging of the masseter muscle sling was observed. This procedure appears to be effective for the reconstruction of sphincter function of the lower lip after wide excision of the entire chin.

Aged↗

PubMed2000

An anatomic examination of the suprascapular flap.

To investigate the potential utility of a suprascapular flap, the authors examined dissected cadavers to identify the ramification of the suprascapular artery, and directly injected 2.5% patent blue dye to observe the distribution of its cutaneous perforators. Results indicate that a suprascapular flap is not practicable. The branching pattern of the suprascapular artery from the subclavian artery varies widely, making dissection of the vessels highly problematic. Moreover, no constant presence of cutaneous perforators from the artery could be identified in either the suprascapular fossa or the shoulder.

Humans↗

PubMed2000

In-vivo and in-vitro evidence of a carrier-mediated efflux transport system for oestrone-3-sulphate across the blood-cerebrospinal fluid barrier.

The efflux transport of oestrone-3-sulphate, a steroid hormone sulphate, across the blood-cerebrospinal fluid barrier has been examined following its intracerebroventricular administration. [3H]Oestrone-3-sulphate was eliminated from cerebrospinal fluid (CSF) with an apparent efflux clearance of 205 microL min(-1) per rat. There was 25% of unmetabolized [3H]oestrone-3-sulphate in the plasma 5 min after intracerebroventricular administration, indicating that at least a part of [3H]oestrone-3-sulphate is transported from CSF to the circulating blood across the blood-CSF barrier. This efflux transport was inhibited by co-administration of excess oestrone-3-sulphate (25 mM 10 microL = 0.25 micromol) into rat cerebral ventricle. To characterize the oestrone-3-sulphate transport process, an in-vitro uptake experiment was performed using isolated rat choroid plexus. Oestrone-3-sulphate uptake by isolated rat choroid plexus was found to be a saturable process with a Michaelis-Menten constant (Km) of 18.1 +/- 6.3 microM, and a maximum uptake rate (Vmax) of 48.0 +/- 15.1 pmol min(-1) microL(-1) of tissue. The oestrone-3-sulphate transport process was temperature dependent and was inhibited by metabolic inhibitors such as 2,4-dinitrophenol and rotenone, suggesting an energy dependence. This uptake process was also inhibited by steroid hormone sulphates (1 mM dehydroepiandrosterone sulphate and 1 mM oestrone sulphate), bile acids (1 mM taurocholic acid and 1 mM cholic acid) and organic anions (1 mM sulphobromophthalein and 1 mM phenolsulphonphthalein), whereas 1 mM p-aminohippuric acid, 1 mM p-nitrophenol sulphate, 0.1 mM methotrexate and the cardiac glycoside, 2.5 microM digoxin, had little effect. In conclusion, these results provide evidence that oestrone-3-sulphate is transported from CSF to the circulating blood across the blood-CSF barrier via a carrier-mediated efflux transport system.

2,4-Dinitrophenol↗

PubMed1999

Reconstitution of protein kinase C-induced contractile Ca2+ sensitization in triton X-100-demembranated rabbit arterial smooth muscle.

1. Triton X-100-demembranated smooth muscle loses Ca2+-sensitizing responsiveness to protein kinase C (PKC) activators while intact and alpha-toxin-permeabilized smooth muscles remain responsive. We attempted to reconstitute the contractile Ca2+ sensitization by PKC in the demembranated preparations. 2. Western blot analyses showed that the content of the PKC alpha-isoform (PKCalpha) was markedly reduced and that the smooth muscle-specific protein phosphatase-1 inhibitor protein CPI-17 was not detectable, while the amount of calponin and actin still remained similar to those of intact strips. 3. Unphosphorylated recombinant CPI-17 alone induced a small but significant contraction at constant Ca2+. Isoform-selective PKC inhibitors inhibited unphosphorylated but not pre-thiophosphorylated CPI-17-induced contraction, suggesting that in situ conventional PKC isoform(s) can phosphorylate CPI-17. 4. Exogenously replenishing PKCalpha alone did not induce potentiation of contraction and only slowly increased myosin light chain (MLC) phosphorylation at submaximal Ca2+. 5. PKC in the presence of CPI-17, but not the [T38A]-CPI mutant, markedly induced potentiation of both contraction and MLC phosphorylation. CPI-17 itself was phosphorylated. 6. In in vitro experiments, CPI-17 was a much better substrate for PKCalpha than calponin, caldesmon, MLC and myosin. 7. Our results indicate that PKC requires CPI-17 phosphorylation at Thr-38 but not calponin for reconstitution of the contractile Ca2+ sensitization in the demembranated arterial smooth muscle.

Animals↗

PubMed1999

Characterization of the muscarinic receptor subtype that mediates the contractile response of acetylcholine in the swine myometrium.

The aim of the present study was to characterize the subtype of muscarinic receptor that mediates acetylcholine-induced contractions in the nonpregnant proestrus swine myometrium by means of mechanical, radioligand ([3H]quinuclidinyl benzilate) binding and biochemical (measurement of cyclic AMP) approaches. Acetylcholine (-logEC50, 6.12), oxotremorine-methiodide (6.47), methacholine (6.35), carbachol (6.18) and muscarine (6.33) caused contractile responses of the uterine circular muscle, with a similar maximum amplitude, but pilocarpine and McN-A-343 (4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium) were ineffective in causing contraction. The contractile response to acetylcholine was antagonized by the following muscarinic receptor antagonists in a competitive manner (with pA2 values in parentheses): atropine (8.95), 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, 8.83), tropicamide (7.07), himbacine (7.01), pirenzepine (6.42) and 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyri do[2,3 b][1,4]benzodiazepin-6-one (AF-DX116, 5.96). Electrical field stimulation (10 Hz) caused tetrodotoxin- and atropine-sensitive contractions in the circular muscle. All muscarinic receptor antagonists decreased the electrical field stimulation-induced contraction in a concentration-dependent manner. The order of inhibition (-logIC50) was 4-DAMP (8.35) > tropicamide (6.72) > himbacine (6.54) > pirenzepine (6.31)> AF-DX116 (6.13). Acetylcholine did not affect the cytoplasmic cyclic AMP level, regardless of the presence or absence of forskolin, suggesting the absence of functional muscarinic M2 and/or M4 receptors in the swine myometrium. The receptor binding study indicated that circular muscle layers of the swine myometrium contained a single class of [3H]quinuclidinyl benzilate binding site (Kd = 0.92 nM; Bmax = 126.6 fmol/mg protein). Specific binding was displaced by muscarinic receptor antagonists in the following order (with pKi value and Hill coefficient in parentheses): atropine (8.22 and 0.93) > 4-DAMP (8.18 and 0.94) > tropicamide (6.78 and 0.93) > pirenzepine (5.46 and 0.92) > AF-DX116 (5.12 and 0.94). The present results suggest that in circular muscle layers of the swine myometrium, exogenous and endogenous acetylcholine cause contraction through activation of muscarinic M3 receptors present on smooth muscle cells.

Acetylcholine↗

PubMed1999

Smooth muscle layer-specific variations in the autonomic innervation of bovine myometrium.

1. To clarify the autonomic innervation regulating longitudinal muscle (LM) and circular muscle (CM) motility in the bovine uterus, functional (nerve stimulation, adrenergic drug responsiveness) and biochemical studies (catecholamine content, radioligand binding) were conducted on parous luteal-phase myometrium. 2. Electrical field stimulation (EFS; 60 V, 0.5-msec duration) caused tetrodotoxin (1 microM)-sensitive contractions in a frequency-dependent manner (0.5-20 Hz) in both LM and CM layers. 3. The EFS-induced LM contractions were potentiated by propranolol and conspicuously decreased by phentolamine, yohimbine, idazoxan or guanethidine, but were unaffected by prazosin or atropine. 4. On the other hand, CM contractions were only slightly decreased by phentolamine, idazoxan, yohimbine and guanethidine, but were insensitive to propranolol, prazosin or atropine. 5. The noradrenaline content in LM was about five times higher than that in CM. 6. Noradrenaline, adrenaline, clonidine, xylazine, UK14,304 and phenylephrine caused concentration-dependent contractions of both smooth muscle layers. 7. Clonidine, UK14,304 and xylazine were more potent contractile agents than noradrenaline and phenylephrine. 8. The contractile response to noradrenaline was competitively antagonized by yohimbine, but not by prazosin. 9. Binding studies using [3H]-prazosin and [3H]-rauwolscine revealed that the bovine myometrium contained both alpha1- and alpha2-adrenoceptors, but the alpha2-type receptor was dominant in both LM (94% of alpha-adrenoceptors) and CM (88%) layers. 10. The distribution of alpha-adrenoceptors was muscle layer-specific; that is, the concentration of alpha1-receptors in LM was the same as in CM, but the concentration of alpha2-receptors in LM was 2.6 times higher than that in CM. 11. The results of the present study indicate that there are layer-specific variations in the functional innervation of the parous bovine myometrium (exclusive adrenergic innervation in LM and adrenergic [minor] plus nonadrenergic, noncholinergic innervation [major] in CM), and that alpha2-adrenoceptors, which were responsive to the excitatory response of endogenous and exogenous noradrenaline, were dominant in both muscle layers of the bovine myometrium.

Adrenergic alpha-Agonists↗

PubMed1999

Inflammatory cell-mediated tumour progression and minisatellite mutation correlate with the decrease of antioxidative enzymes in murine fibrosarcoma cells.

We isolated six clones of weakly tumorigenic fibrosarcoma (QR) from the tumorigenic clone BMT-11 cl-9. The QR clones were unable to grow in normal C57BL/6 mice when injected s.c. (1x10(5) cells). However, they formed aggressive tumours upon co-implantation with a 'foreign body', i.e. a gelatin sponge, and the rate of tumour take ranged from 8% to 58% among QR clones. The enhanced tumorigenicity was due to host cell-mediated reaction to the gelatin sponge (inflammation). Immunoblot analysis and enzyme activity assay revealed a significant inverse correlation between the frequencies of tumour formation by QR clones and the levels of manganese superoxide dismutase (Mn-SOD, P<0.005) and glutathione peroxidase (GPchi, P<0.01) in the respective tumour clones. Electron spin resonance (ESR) revealed that superoxide-scavenging ability of cell lysates of the QR clone with high level of Mn-SOD was significantly higher than that with low level of the antioxidative enzyme in the presence of potassium cyanide, an inhibitor for copper-zinc superoxide dismutase (CuZn-SOD) (P<0.001). Minisatellite mutation (MSM) induced by the inflammatory cells in tumour cells were investigated by DNA fingerprint analysis after QR clones had been co-cultured with gelatin-sponge-reactive cells. The MSM rate was significantly higher in the subclones with low levels of Mn-SOD and GPchi (P<0.05) than in the subclones with high levels of both enzymes. The MSM of the subclones with low levels of both enzymes was inhibited in the presence of mannitol, a hydroxyl radical scavenger. The content of 8-hydroxydeoxyguanosine (8-OHdG) by which the cellular DNA damage caused by active oxygen species can be assessed was significantly low in the tumours arising from the QR clone with high levels of Mn-SOD and GPchi even if the clone had been co-implanted with gelatin sponge, compared with the arising tumour from the QR clone with low levels of those antioxidative enzymes (P<0.001). In contrast, CuZn-SOD and catalase levels in the six QR clones did not have any correlation with tumour progression parameters. These results suggest that tumour progression is accelerated by inflammation-induced active oxygen species particularly accompanied with declined levels of intracellular antioxidative enzymes in tumour cells.

Animals↗

PubMed1999

Mechanisms of 5-hydroxytryptamine-induced inhibition in the porcine myometrium.

The present experiments were designed to clarify the mechanisms of the inhibitory response of 5-hydroxytryptamine (5-HT) in the porcine uterine circular muscle. Inhibitory responses induced by 5-HT (1 nM-1 microM) were not affected by apamin (1 microM), charybdotoxin (100 nM) or glibenclamide (20 microM) but were significantly attenuated by 4-aminopyridine (3 mM) and tetraethylammonium (3 mM). Imidazole (100 microM) decreased but 3-isobutyl-1-methylxanthine (30 microM), milrinone (30 microM) and Ro 20-1724 (10 and 30 microM) potentiated the 5-HT-induced inhibition. On the other hand, zaprinast (3-30 microM) had no significant effect on the inhibitory response of 5-HT. 5-HT caused a time (0-5 min)-and concentration (1 nM-1 microM)-dependent increase in the tissue cyclic AMP level, but had no effect on the tissue cyclic GMP level. A significant correlation (P < 0.05) was observed between the inhibition of contraction and tissue cyclic AMP level. The effect of 5-HT on contractile force and cytosolic Ca2+ level ([Ca2+]i) was investigated using fura-PE3-loaded myometrial strips. A low concentration of 5-HT (< or = 10 nM) inhibited the spontaneous contraction without changing the amplitude of the spontaneous [Ca2+]i increase, but a higher concentration of 5-HT (> or = 100 nM) decreased the resting [Ca2+]i and inhibited both the spontaneous [Ca2+]i increase and spontaneous contraction. High-K+ (50 mM) caused increases in muscle contractile force and [Ca2+]i. 5-HT concentrationdependently inhibited the high-K(+)-induced contraction (EC50, 45 nM) with only a small decrease in [Ca2+]i increase. Carbachol also caused increases in muscle contractile force and [Ca2+]i. 5-HT significantly decreased both the carbachol-induced contraction and [Ca2+]i increase, but was more potent at inhibition of contractile force than [Ca2+]i. In Ca(2+)-loaded myometrial strips, carbachol, but not caffeine, caused a transient increase in [Ca2+]i and contraction in the absence of external Ca2+ (EGTA, 1 mM). 5-HT inhibited both the carbachol-induced increases in [Ca2+]i release and contractile force. In the beta-escin permeabilized myometrium, 5-HT significantly inhibited the Ca(2+)-induced contraction. The present results indicate that 5-HT stimulates tissue cyclic AMP production, and inhibits the porcine uterine muscle contractility by a reduction in [Ca2+]i and in Ca2+ sensitivity of the contractile elements. Activation of K+ channels might be partially involved in 5-HT-induced inhibition of the myometrial contractility.

Animals↗

PubMed1999

Bipedicled submental island flap for upper lip reconstruction.

A case of reconstruction of the upper lip with a bipedicled submental flap is described. Although the mobility of the flap was restricted, the arterial blood supply was abundant by altering the single-pedicled flap into a bipedicled flap. This flap is a good color and texture match to the face, and surpasses other flaps in reconstruction of the mustache or beard in male patients.

Humans↗

PubMed1999

Chondroid syringoma of the orbit.

Chondroid syringoma is a rare subcutaneous tumor that mainly affects the face and the neck. The authors present an occurrence in the orbit, which they believe to be the first reported at that site. Computed tomography and magnetic resonance imaging suggested that the tumor had invaded the globe, but at surgery the mass was well circumscribed and did not invade or adhere to other structures. The tumor was resected easily under general anesthesia. Epithelial cells of characteristic appearance within a chondroid matrix were demonstrated histologically. No recurrence has been evident in more than 1 year of follow-up. Most chondroid syringomas are benign, but because several cases have exhibited malignant behavior, periodic observation following complete resection is required.

Adenoma, Pleomorphic↗

PubMed1999

Ca2+ -induced Ca2+ desensitization of myosin light chain phosphorylation and contraction in phasic smooth muscle.

The temporal relationship between Ca2+ -induced contraction and phosphorylation of 20 kDa myosin light chain (MLC) during a step increase in Ca2+ was investigated using permeabilized phasic smooth muscle from rabbit portal vein and guinea-pig ileum at 25 degrees C. We describe here a Ca2+ -induced Ca2+ desensitization phenomenon in which a transient rise in MLC phosphorylation is followed by a transient rise in contractile force. During and after the peak contraction, the force to phosphorylation ratio remained constant. Further treatment with cytochalasin D, an actin fragmenting agent, did not affect the transient increase in phosphorylation, but blocked force development. Together, these results indicate that the transient phosphorylation causes the transient contraction and that neither inhomogeneous contractility nor reduced thin filament integrity effects the transient phosphorylation. Lastly, we show that known inhibitors to MLC kinase kinases and to a Ca2+ -dependent protein phosphatase did not eliminate the desensitized contractile force. This study suggests that the Ca2+ -induced Ca2+ desensitization phenomenon in phasic smooth muscle does not result from any of the known intrinsic mechanisms involved with other aspects of smooth muscle contractility.

Animals↗

PubMed1999

Transepithelial transport of organic anions across the choroid plexus: possible involvement of organic anion transporter and multidrug resistance-associated protein.

Transport characteristics of 17beta-estradiol 17beta-D-glucuronide (E217betaG), a dual substrate of the transporters for cellular uptake (organic anion-transporting polypeptide 1 or oatp1) and cellular excretion (multidrug resistance-associated protein 1or MRP1), in the rat choroid plexus were studied in vivo and in vitro. The uptake of E217betaG into isolated choroid plexus was mediated by an energy-dependent system with a Km of 3.4 microM. Together with the previous finding that oatp1 is localized on the apical membrane of choroid plexus, these results suggest that oatp1 is responsible for the uptake of this ligand. After intracerebroventricular administration, elimination of E217betaG from cerebrospinal fluid was probenecid sensitive and much more rapid than that of inulin; less than 2% of the administered E217betaG and 40 to 50% of inulin remained in the cerebrospinal fluid 20 min after intracerebroventricular administration. In addition, the amount of E217betaG associated with choroid plexus at 20 min was negligible, suggesting the presence of an efficient excretion system on the basolateral membrane of choroid plexus. Expression of MRP1 was detected in choroid plexus. Semiquantitative reverse transcription-polymerase chain reaction and Western blot analyses indicated that the expression level of MRP1 in choroid plexus is about four or five times higher than that in the lung, one of the tissues exhibiting high expression of MRP1. Together with the in vivo vectorial transport of E217betaG, these results can be accounted for by assuming that there is basolateral localization of MRP1 in choroid plexus. Combined, oatp1 and MRP1 may synergistically mediate the efficient transcellular transport of E217betaG across choroid plexus.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Possible involvement of the novel CPI-17 protein in protein kinase C signal transduction of rabbit arterial smooth muscle.

1. CPI-17 has recently been identified as a novel protein in vascular smooth muscle. In vitro , its phosphorylation and thiophosphorylation by protein kinase C (PKC) specifically inhibits the type 1 class of protein phosphatases, including myosin light chain (MLC) phosphatase. 2. Both of the phosphorylated CPI-17 states dose-dependently potentiated submaximal contractions at constant [Ca2+] in beta-escin-permeabilized and Triton X-100-demembranated arterial smooth muscle, but produced no effect in intact and less intensely permeabilized (alpha-toxin) tissue. Thiophosphorylated CPI-17 (tp-CPI) induced large contractions even under Ca2+-free conditions and decreased Ca2+ EC50 by more than an order of magnitude. Unphosphorylated CPI-17 produced minimal but significant effects. 3. tp-CPI substantially increased the steady-state MLC phosphorylation to Ca2+ ratios in beta-escin preparations. 4. tp-CPI affected the kinetics of contraction and relaxation and of MLC phosphorylation and dephosphorylation in such a manner that indicates its major physiological effect is to inhibit MLC phosphatase. 5. Results from use of specific inhibitors in concurrence with tp-CPI repudiate the involvement of general G proteins, rho A or PKC itself in the Ca2+ sensitization by tp-CPI. 6. Our results indicate that phosphorylation of CPI-17 by PKC stimulates binding of CPI-17 to and subsequent inhibition of MLC phosphatase. This implies that CPI-17 accounts largely for the heretofore unknown signalling pathway between PKC and inhibited MLC phosphatase.

Animals↗

PubMed1998

Involvement of 5-hydroxytryptamine7 receptors in inhibition of porcine myometrial contractility by 5-hydroxytryptamine.

1 5-Hydroxytryptamine (5-HT; 1 nM - 100 microM) concentration-dependently inhibited the amplitude and frequency of spontaneous contractions in longitudinal and circular muscles of the porcine myometrium. The circular muscle (EC50; 68-84 nM) was more sensitive than the longitudinal muscle (EC50; 1.3-1.44 microM) to 5-HT. To characterize the 5-HT receptor subtype responsible for inhibition of myometrial contractility, the effects of 5-HT receptor agonists on spontaneous contractions and of 5-HT receptor antagonists on inhibition by 5-HT were examined in circular muscle preparations. 2 Pretreatment with tetrodotoxin (1 microM), propranolol (1 microM), atropine (1 microM), guanethidine (10 microM) or L-NAME (100 microM) failed to change the inhibition by 5-HT, indicating that the inhibition was due to a direct action of 5-HT on the smooth muscle cells. 3 5-CT, 5-MeOT and 8-OH-DPAT mimicked the inhibitory response of 5-HT, and the rank order of the potency was 5-CT>5-HT>5-MeOT>8-OH-DPAT. On the other hand, oxymethazoline, alpha-methyl-5-HT, 2-methyl-5-HT, cisapride, BIMU-1, BIMU-8, ergotamine and dihydroergotamine had almost no effect on spontaneous contractions, even at 10-100 microM. 4 Inhibition by 5-HT was not decreased by either pindolol (1 microM), ketanserin (1 microM), tropisetron (10 microM), MDL72222 (1 microM) or GR113808 (10 microM), but was antagonized by the following compounds in a competitive manner (with pA2 values in parentheses): methiothepin (8.05), methysergide (7.92), metergoline (7.4), mianserin (7.08), clozapine (7.06) and spiperone (6.86). 5 Ro 20-1724 (20 microM) and rolipram (10 microM) significantly enhanced the inhibitory response of 5-HT, but neither zaprinast (10 microM) nor dipyridamole (10 microM) altered the response of 5-HT. 6 5-HT (1 nM - 1 microM) caused a concentration-dependent accumulation of intracellular cyclic AMP in the circular muscle. 7 From the present results, the 5-HT receptor, which is functionally correlated with the 5-HT7 receptor, mediates the inhibitory effect of 5-HT on porcine myometrial contractility. This inhibitory response is probably due to an increase in intracellular cyclic AMP through the activation of adenylate cyclase that is positively coupled to 5-HT7 receptors.

Adenylyl Cyclases↗

PubMed1998

Efflux of taurocholic acid across the blood-brain barrier: interaction with cyclic peptides.

The mechanism for the efflux of taurocholic acid (TC) across the blood-brain barrier (BBB) was studied by examining the elimination of [3H]TC after microinjection into the cerebral cortex. The efflux of [3H]TC from the brain was saturable with a Vmax of 15.0 pmol/min/g brain and a Km value of 0.396 nmol/0.2 microl injectate. Efflux was inhibited by cholic acid (CA), a cationic cyclic octapeptide (octreotide; a somatostatin analogue) and an anionic cyclic pentapeptide (BQ-123; an endothelin receptor antagonist), with an IC50 value of 1.09 nmol/0.2 microl injectate, 1.12 nmol/0.2 microl injectate and 0.12 nmol/0.2 microl injectate, respectively. Probenecid (20 nmol/0.2 microl injectate), but not p-aminohippuric acid (10 nmol/0.2 microl injectate), inhibited the brain efflux of [3H]TC. In addition, elimination of [3H]BQ-123 after microinjection was saturable with a Vmax of 20.8 pmol/min/g brain and a Km of 2.92 nmol/0.2 microl injectate; it was also inhibited by TC with an IC50 value of 0.074 nmol/0.2 microl injectate. In contrast, no significant efflux of [14C]octreotide from the brain was observed until 60 min after microinjection. These results suggest that both TC and BQ-123 are transported from the brain to the circulating blood across the blood-brain barrier via specific mechanisms. Although mutual inhibition was observed between TC and BQ-123, kinetic analysis suggested that the two transport systems differ.

Animals↗

PubMed1997

Repeated elicitation of contact hypersensitivity induces a shift in cutaneous cytokine milieu from a T helper cell type 1 to a T helper cell type 2 profile.

We previously demonstrated that repeated application of 2,4,6-trinitro-1-chlorobenzene resulted in a site-restricted shift in the time course of Ag-specific hypersensitivity responses from a typical delayed-type to an early-type response. Here we demonstrated that the cutaneous microenvironment at the time of Ag presentation to T cells in the elicitation, but not the induction, phase of contact hypersensitivity is responsible for the shift. To investigate the differences in the cutaneous cytokine milieu between the acute and chronic phases of contact hypersensitivity, sequential cytokine dynamics after 2,4,6-trinitro-1-chlorobenzene application were assessed in the acute vs chronic lesions. In the acute lesions, increased mRNA levels for IFN-gamma and IL-2 were rapidly detected at 1 h and remained elevated at 12 h, while mRNA expression for IL-4 and IL-10 was minimally up-regulated between approximately 12 and 24 h. In chronic lesions, high levels of constitutive expression of IL-4 mRNA were observed and IL-10 mRNA was dramatically up-regulated at 1 approximately 3 h in an Ag-specific fashion, whereas the expression of Th1-type cytokines was markedly reduced. Increased mRNA levels for Th2-type cytokines in the chronic lesions was also reflected at the protein level. These results indicate that repeated elicitation with Ag alters the balance of cytokines released locally, with a shift toward Th2-dominated responses, which would represent the natural evolution processes directed toward reducing a more deleterious Th1 response.

Administration, Cutaneous↗

PubMed1997

Functional characterization of neural and smooth muscle motilin receptors in the chicken proventriculus and ileum.

To characterize the motilin receptors present in the chicken, the effects of chicken motilin (Phe-Val-Pro-Phe-Phe-Thr-Gln-Ser-Asp-Ile-Gln-Lys-Met-Gln-Glu-Lys-Glu-Arg -Asn-Lys-Gly-Gln), Leu13 porcine motilin, canine motilin and three erythromycin derivatives (EMA, EM523, GM611) on the contractility of the chicken gastrointestinal (GI) smooth muscles were investigated in vitro and compared with those in the rabbit duodenum. In the proventriculus longitudinal and circular muscle layers, chicken motilin (3 nM-1 microM) caused an atropine- and a tetrodotoxin-sensitive contraction (EC50 = 39-49 nM), and potentiated the EFS-induced contraction without affecting the responsiveness of acetylcholine. EM523 and GM611 (3-100 microM) contracted the proventriculus longitudinal muscle, and the maximum amplitudes of contraction were about 60% of that induced by chicken motilin. Chicken motilin (0.1 nM-100 nM) also caused contraction of the ileum (EC50 = 7 nM) through direct action on the smooth muscle cells. On the other hand, erythromycin derivatives showed only a weak contractile efficacy (about 20% of the maximum response of chicken motilin) even at high concentrations (10-100 microM). The rank order of potency in the ileum was chicken motilin > canine motilin > or = Leu13 porcine motilin > > GM611 > or = EM523 > or = EMA. GM109 slightly inhibited the ideal contractions induced by Leu13 porcine motilin at 100 microM (pA2 = 3.86). In the rabbit duodenum, chicken motilin was a full agonist with the same intrinsic activity as Leu13 porcine motilin, canine motilin and the erythromycin derivatives. However, the rank order of potency (Leu13 porcine motilin > or = canine motilin > chicken motilin > GM611 > or = EM523 > EMA) was different from that in the chicken ileum. In conclusion, chicken motilin causes an excitatory response in the chicken GI tract through activation of neural (proventriculus) and smooth muscle motilin receptors (ileum). The motilin receptor present in the ileum is different from that demonstrated in the rabbit intestine, because of a different rank order of motilin peptides in producing the contraction, low contracting activity of erythromycin derivatives and low antagonistic efficacy of GM109. Different pharmacological characteristics of the mechanical response induced by motilin peptides and erythromycin derivatives between the proventriculus and the ileum are discussed.

Animals↗