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K Tsuchida

Publications and source records attributed to K Tsuchida.

At least 163 records · Page 9Linked to original sources
PubMed1991

Sequence and expression of a metabotropic glutamate receptor.

The complementary DNA of a metabotropic glutamate receptor coupled to inositol phosphate/Ca2+ signal transduction has been cloned and characterized. This receptor shows no sequence similarity to conventional G protein-coupled receptors and has a unique structure with large hydrophilic sequences at both sides of seven putative membrane-spanning domains. Abundant expression of this messenger RNA is observed in neuronal cells in hippocampal dentate gyrus and CA2-3 and in cerebellar Purkinje cells, suggesting the importance of this receptor in specific hippocampal and cerebellar functions.

Amino Acid Sequence↗
PubMed1991

Adenosine deaminase deficiency due to heterozygous abnormality consisting of a deletion of exon 7 and the absence of enzyme mRNA.

An adenosine deaminase (ADA;EC 3.5.4.4)-deficient B lymphoblastoid cell line BADO5 derived from a Japanese patient with severe combined immunodeficiency disease and two B lymphoblastoid cell lines, BAMO5 from his mother and BAFO5 from his father, were characterized. To identify mutations affecting ADA activity, we prepared cDNAs to ADA mRNAs of the BADO5 cell line for nucleotide sequencing. Sequence analysis of one of the BADO5 ADA cDNA clones revealed deletion of exon 7, and one point mutation of base 629 from G to A that did not affect the amino acid sequence. All clones of the BADO5 cell line so far examined showed the absence of exon 7 by Southern blotting analysis. Ribonuclease protection assay with an RNA probe spanning from exon 5 to exon 11 showed that the BADO5 ADA mRNA had a deletion of exon 7, the BAMO5 mRNA had normal length, and the BAFO5 mRNA had two species with a deletion of exon 7 and with normal length. Consequently, the patient's ADA genes resulted from one allele of the BAMO5 ADA gene that did not produce a detectable mRNA, and the other allele of the BAFO5 ADA gene producing an aberrant mRNA without exon 7.

Adenosine Deaminase↗
PubMed1991

Protein kinase C-mediated contraction in rabbit aorta is inhibited by CD-349, a dihydropyridine derivative.

We investigated the effects of nitroglycerin (NTG), atrial natriuretic peptide (ANP), and CD-349 on phorbol dibutyrate (PDBu)-induced contraction in rabbit aorta. In the presence of endothelium, both NTG (10(-8)-10(-5) M) and ANP (10(-10)-10(-7) M) inhibited the PDBu-induced contraction in a concentration-dependent manner. CD-349 (10(-8)-10(-5) M) also inhibited the PDBu-induced contraction in a concentration-dependent manner. This inhibitory effect of CD-349 was independent of the existence of endothelium. Inhibitory effects of both NTG and CD-349 but not ANP were antagonized by treatment with methylene blue. However, nifedipine (10(-5) M), nicardipine (10(-5) M), and diltiazem (10(-5) M) had little or no effect on PDBu-induced contraction. Furthermore, NTG, ANP, and CD-349 inhibited endothelin-induced contraction, which may be mediated through activation of protein kinase C. These results indicate that PDBu-induced and endothelin-induced contractions in rabbit aorta are inhibited by agents known to elevate vascular cyclic GMP content.

Animals↗
PubMed1991

Electrophysiological effects of CD-349, a dihydropyridine-type calcium antagonist, on goat cardiac Purkinje fibers.

We examined the calcium antagonistic action of CD-349, a dihydropyridine derivative, on goat cardiac Purkinje fibers using the two-microelectrode voltage-clamp method. CD-349 at a concentration of 10(-5) M shortened the action potential duration without changing the maximum rise in the action potential (Vmax) in goat Purkinje fibers. CD-349 at 3 x 10(-7) to 3 x 10(-6) M inhibited the slow inward current (Isi) in a concentration-dependent manner. At the holding potential of -55 mV, CD-349 exerted a tonic block of Isi, and, furthermore, it exerted a use-dependent block at a frequency range of 1 Hz, but it did not exert a use-dependent block at 0.5 and 0.2 Hz. This may be because CD-349 delayed the recovery process from the inactivation of Isi. The amplitude of the block of Isi was larger at the holding potential of -45 mV than at -55 mV. The inactivation curve of Isi shifted toward a negative potential in the presence of CD-349. Nifedipine also exerted a tonic block of Isi. The onset of the action of nifedipine was quicker than that of CD-349 or nitrendipine. A use-dependent block at 1 Hz and delay of the recovery process from inactivation was also observed with nifedipine. The inactivation curve shifted toward the negative potential with nifedipine. On washout of the drugs, the effects of CD-349 or nitrendipine were not readily reversed compared with those of nifedipine. CD-349 had no effect on either inward rectifying (IK1) or delayed outward potassium (IK) or hyperpolarization-activated inward (If) currents. These observations suggest that, in cardiac tissues, CD-349 selectively inhibits the calcium current, presumably by acting on the inactivated channel.

Action Potentials↗
PubMed1991

[Effect of surgery for combined abdominal aortic and internal iliac artery aneurysm on postoperative intestinal ischemia and sexual dysfunction].

The effect of surgery for combined abdominal aortic aneurysm (AAA) and internal iliac artery aneurysm (IIAA) on postoperative intestinal ischemia and sexual dysfunction was studied. Nineteen men and three women, aged 51 to 79 years, were included in this study. The IIAA was unilateral in 13 cases and bilateral in 9. The maximum diameter of the IIAAs ranged from 3.0 to 7.5 cm. Seven cases underwent emergent surgery for aneurysmal rupture. A bifurcated graft was implanted in all cases. Among cases with unilateral IIAA, aneurysmectomy and IIA reconstruction was performed in 2 cases, and ligation of the IIA was performed in the remaining 11. Among cases with bilateral IIAAs, IIA reconstruction was performed on one side and IIA ligation on the another side in 1 case. Bilateral ligation was performed in 4 and exclusion of the AAA and both IIAAs were performed in 4. The inferior mesenteric artery was reconstructed in 10 cases. The average postoperative follow-up period was 6.2 years. Postoperatively 2 cases experienced bowel necrosis and 4 had diarrhea and/or mucous stool. An erectile disturbance occurred postoperatively in 33.3% of cases which had undergone unilateral and 50% of cases which had undergone bilateral IIA ligation.

Adult↗
PubMed1991

[Coronary artery spasm after aortic valve replacement: a case report].

A 64-year-old man who had aortic valve regurgitation underwent aortic valve replacement. There had been no history of angina pectoris or taking of calcium channel blockers. When the operation was nearly completed, unexpected hemodynamic collapse happened without ST-segment changes on the ECG monitoring. Resuscitation was successful by cardiac massage, pacing and administration of catecholamine. Thereafter the same episodes occurred several times. At the 6th attack on postoperative day 7, we confirmed the ST-segment elevation using 12-lead-ECG, thus coronary artery spasm was diagnosed. Thereafter calcium channel blocker and coronary vasodilator were administered continuously. There has been no attack since postoperative day 13. Though postoperative coronary arteriography showed no anatomical changes compared with preoperative study, direct injection of ergonovine made the right coronary artery spastic, but not the left. We emphasized that perioperative coronary artery spasm may happen not only in the coronary artery surgery but in any other cardiac operations.

Aortic Valve↗
PubMed1991

[An emergent aortic and mitral valve replacement for active infective endocarditis preoperatively using extracorporeal ultrafiltration method].

We reported a 29-year-old man with active endocarditis complicating aortic and mitral valve regurgitation. The echocardiogram showed a mycotic aneurysm at aortic valvular annulus and a aneurysm of mitral valve. Heart failure was progressive and caused anuria. Prior to emergent double valve replacement, 2,500 ml of water was removed. Then hemodynamics became stationary. Urination was good during and after operation. In this case, complicating acute renal failure, dehydration with extracorporeal ultrafiltration method was very effective for improvement of hemodynamics.

Adult↗
PubMed1991

[Prevention of cerebral complications during thoracic aortic aneurysms operation: study of preoperative selective cerebral arteriography].

Preoperative selective cerebral arteriography is carried out in order to determine if the circle of Willis is intact in the cases of the thoracic aortic aneurysms. As regard to the bilateral vertebrobasilar communications, 26 of 30 patients (86.7%) have good condition, 4 of 30 patients (13.3%) have poor, and in 2 cases the left vertebral artery supplied broad area of posterior cranial fossa. We believe that in the cases in whom the left vertebral artery is dominant, and cross collateral circulation is absent, perfusion of the left subclavian artery is necessary to prevent vertebrobasilar ischemia during aortic aneurysms operation under normothermia.

Adult↗
PubMed1990

Electrophysiological effects of monensin, a sodium ionophore, on cardiac Purkinje fibers.

Monensin, a monovalent cation ionophore, transports sodium ions preferentially. We found that, in the cardiac Purkinje fibers, monensin 10(-5) M increased the resting tension of the fiber bundle in Tyrode solution containing 4.5 mM Ca. This ionophore (10(-5) M) shortened the duration of the action potential and suppressed the pacemaker potential. In Na-free or Ca-free solutions, monensin had no effect on the configuration of the action potential. In voltage clamp experiments, monensin 10(-5) M shifted the holding current at -40 mV outwardly, increased the instantaneous inward current (possibly inward rectifying potassium current, IK1) and increased the transient outward current (Ito), whereas it attenuated the hyperpolarization-activated inward current (If). The delayed rectifying outward current (IK) was not significantly affected by monensin 10(-5) M. The transient inward current (ITI) appeared in the presence of monensin 10(-5) M. These changes induced by monensin are consistent with changes in configuration of the action potential induced by monensin. The membrane current changes are considered to be induced by an increase in intracellular Ca concentration, probably via a Na-Ca exchange following an increase in intracellular Na concentration, and by alteration of intra- and extracellular Na and K concentrations.

Action Potentials↗
PubMed1990

Tissue distribution and quantitation of the mRNAs for three rat tachykinin receptors.

The family of mammalian tachykinin receptors consists of substance P receptor (SPR), neuromedin K receptor (NKR) and substance K receptor (SKR). In this investigation, tissue and regional distributions of the mRNAs for the three rat tachykinin receptors were investigated by blot-hybridization and RNase-protection analyses using the previously cloned receptor cDNAs. SPR mRNA is widely distributed in both the nervous system and peripheral tissues and is expressed abundantly in the hypothalamus and olfactory bulb, as well as in the urinary bladder, salivary glands and small and large intestines. In contrast, NKR mRNA is predominantly expressed in the nervous system, particularly in the cortex, hypothalamus and cerebellum, whereas SKR mRNA expression is restricted to the peripheral tissues, being abundant in the urinary bladder, large intestine, stomach and adrenal gland. Thus, the mRNAs for the three tachykinin receptors show distinct patterns of expression between the nervous system and peripheral tissues. Blot-hybridization analysis in combination with S1 nuclease protection and primer-extension analyses revealed that there are two large forms of SKR mRNA expressed commonly in the peripheral tissues, and two additional small forms of the mRNA expressed specifically in the adrenal gland and eye. These analyses also showed that the multiple forms of SKR mRNA differ in the lengths of the 5' mRNA portions, and that the two small forms of the mRNA, if translated, encode a truncated SKR polypeptide lacking the first two transmembrane domains. This investigation thus provides the comprehensive analysis of the distribution and mode of expression of the mRNAs for the multiple peptide receptors and offers a new basis on which to interpret the diverse functions of multiple tachykinin peptides in the CNS and peripheral tissues.

Animals↗
PubMed1990

Isolation and characterization of a lipoprotein receptor from the fat body of an insect, Manduca sexta.

A lipoprotein receptor has been purified from the fat body of Manduca sexta larvae. The purification involves solubilization of membrane proteins in detergent, DEAE-, and hydroxyapatite chromatography, affinity chromatography on a concanavalin A column, and affinity chromatography on a lipoprotein-Sepharose column. An overall purification of 220-fold from the solubilized membranes was achieved. The receptor has an apparent molecular mass of 120 kDa. The receptor has an absolute requirement for Ca2+ and is inhibited by Suramin. The pH optimum of the receptor is 6.5, which is near the pH of the hemolymph. Binding data indicate a single high affinity binding site with a Kd = 4.1 +/- 0.19 x 10(-8) M as measured with the lipoprotein isolated from larval hemolymph. The major neutral lipid carried by insect lipoproteins is diacylglycerol, and it was shown that the affinity of the receptor for lipoprotein ligands correlates with their diacylglycerol content. It is proposed that the decrease in affinity of the receptor for lipoproteins depleted of diacylglycerol plays a key role in facilitating the transport of diacylglycerol from the midgut to the fat body during the larval feeding period. The insect receptor has some properties which are similar to those of vertebrate lipoprotein receptors, viz. molecular weight, requirement for Ca2+, and inhibition by Suramin. However, the insect receptor does not bind human low density lipoprotein.

Animals↗
PubMed1990

Cloning and expression of a rat neuromedin K receptor cDNA.

Functional cDNA clones for rat neuromedin K receptor were isolated from a rat brain cDNA library by cross-hybridization with the bovine substance K receptor cDNA. Injection of the mRNA synthesized in vitro from the cloned cDNA into Xenopus oocytes elicited electrophysiological responses to tachykinins, with the most potent sensitivity being to neuromedin K. Ligand-binding displacement in membranes of mammalian COS cells transfected with the cDNA indicated the rank order of affinity of the receptor to tachykinins: neuromedin K greater than substance K greater than substance P. The hybridization analysis showed that the neuromedin K receptor mRNA is expressed in both the brain and the peripheral tissues at different levels. The rat neuromedin K receptor consists of 452 amino acid residues and belongs to the family of G protein-coupled receptors, which are though to have seven transmembrane domains. The sequence comparison of the rat neuromedin K, substance P, and substance K receptors revealed that these receptors are highly conserved in the seven transmembrane domains and the cytoplasmic sides of the receptors. They also show some structural characteristics, including the common presence of histidine residues in transmembrane segments V and VI and the difference in the numbers and distributions of serine and threonine residues as possible phosphorylation sites in the cytoplasmic regions. This paper thus presents the first comprehensive analysis of the molecular nature of the multiple peptide receptors that exhibit similar but pharmacologically distinguishable activities.

Amino Acid Sequence↗
PubMed1990

Mechanisms of inhibitory effects of CD-349 and K(+)-channel activators on noradrenaline-induced contraction and changes in levels of cyclic GMP in rat aorta.

1. CD-349 inhibited the noradrenaline (NA)-induced contraction of aortas in Ca2(+)-free medium. 2. This inhibitory effect was completely antagonized by pretreatment with methylene blue. 3. Nicorandil and cromakalim also inhibited the NA-induced contraction of aortas in Ca2(+)-free medium. 4. The inhibitory effects of nicorandil, but not those of cromakalim, were partially antagonized by pretreatment with methylene blue. 5. The methylene blue-insensitive effects of nicorandil and the effects of cromakalim were antagonized by pretreatment with glibenclamide. 6. These results indicate that the inhibitory effect of CD-349 and nicorandil on NA-induced contraction of aortic strips in Ca2(+)-free medium is mediated through increased levels of cyclic GMP. 7. Furthermore, the inhibitory effect of cromakalim and the partial inhibitory mechanism of nicorandil may be mediated through glibenclamide-sensitive K(+)-channels.

Animals↗
PubMed1990

Characterization of gene organization and generation of heterogeneous mRNA species of rat ISK protein.

The ISK protein is a novel, probably epithelial potassium channel which differs from conventional potassium channels in its structure, electrophysiology, and tissue distribution. In this investigation, we isolated and analyzed genomic and cDNA clones coding for the rat ISK protein to characterize the structural organization and expression pattern of the ISK protein gene. This analysis, together with primer extension and RNase protection experiments, indicated that the ISK protein mRNA is initiated from two different upstream exons and then encoded by an uninterrupted downstream exon covering the protein-coding and the 3'-untranslated regions of the mRNA. RNA blot hybridization analysis showed additional generation of several large species of mRNAs which result from inclusion of a part of the intron sequence and the 3'-flanking region of the ISK protein gene. Thus, the single ISK protein gene is involved in the production of multiple species of mRNAs through a variety of cellular mechanisms including transcription initiation at different sites, alternative RNA splicing, and polyadenylation at different sites. The heterogeneity of the ISK protein mRNAs may be associated with the emergence of the functional and regulatory diversity observed for potassium ion permeation in epithelial cells.

Animals↗
PubMed1990

Impairment of endothelium-dependent relaxation and changes in levels of cyclic GMP in carotid arteries from stroke-prone spontaneously hypertensive rats.

Endothelium-dependent relaxation of carotid arteries and changes in levels of cyclic (c)GMP between stroke-prone spontaneously hypertensive (SHRSP) and Wistar-Kyoto (WKY) rats have been compared. The concentration-response curve for acetylcholine (ACh)-induced relaxation was shifted to the right in carotid arteries from SHRSP. Relaxation responses produced by calcimycin (A 23187) and melittin, both endothelium-dependent agents, were depressed in carotid arteries from SHRSP. Relaxation responses produced by sodium nitroprusside and 8-Br-cGMP were similar to those in strips from WKY. ACh-induced production of cGMP was significantly decreased in carotid arteries from SHRSP when compared with the level for similarly treated strips from WKY. These results suggest that functional changes in endothelium, but not guanylate cyclase activity or cGMP sensitivity in the carotid arteries, may occur in hypertension. Thus, impaired endothelium-dependent relaxation in SHRSP may play an important role in hypertensive vascular diseases such as stroke.

Acetylcholine↗
PubMed1990

Effects of dihydroergotamine and etilefrine on experimentally-induced postural hypotension in dogs.

The effects of dihydroergotamine and etilefrine on experimentally-induced postural hypotension were examined. Although dihydroergotamine at 3 and 10 micrograms/kg (i.v.) increased blood pressure (BP), it did not affect cardiac output (CO). However, dihydroergotamine at 10 micrograms/kg reduced the decrease in CO induced by the tilt. Therefore, it is suggested that the increase in BP is induced by the contraction of resistance vessels, and that the inhibition of the decrease in CO due to tilt is induced by the contraction of capacitance vessels. Etilefrine at 0.1 mg/kg (i.v.) increased BP and heart rate (HR), however, it did not attenuate the decrease in BP induced by the tilt. Although it tended to increase CO, it did not attenuate the decrease in CO. It is suggested that the increase in BP is due to the contraction of resistance vessels, and to the increase in cardiac contractile force and HR. In this study, dihydroergotamine and etilefrine did not attenuate the decrease in BP due to tilt, though dihydroergotamine inhibited the decrease in CO due to tilt. As an explanation, it is suggested that dihydroergotamine induces contraction of resistance vessels as well as capacitance vessels, however the effects of the drug on resistance vessels is weak, and that etilefrine has little or no effect on capacitance vessels. In our previous study, midodrine, an alpha-1 agonist, attenuated the decreases in BP and CO due to tilt, and it has been suggested that the inhibition was induced by the contraction of capacitance vessels. Therefore, dihydroergotamine, etilefrine and midodrine show different pahrmacological profiles in experimentally-induced postural hypotension.

Anesthesia↗
PubMed1990

Hemodynamic effects of a potassium ionophore, lonomycin A.

Lonomycin A, an ionophorous antibiotic, exhibits a high transport rate for monovalent cations, especially potassium. The cardiovascular actions of lonomycin A were studied in anesthetized dogs. Lonomycin A administered intravenously at 30 micrograms/kg increased coronary blood flow slightly with relatively small alterations in other hemodynamic parameters. After 100 micrograms/kg, a slight and transient fall followed by an increase in blood pressure was observed. Coronary blood flow, cardiac output, left ventricular pressure, max dP/dt, and isometric ventricular segmental tension increased. Arterial venous O2 difference and total peripheral vescular resistance decreased. Above 300 micrograms/kg, dramatic alterations were produced in almost all hemodynamic parameters, and total peripheral vascular resistance was increased. Lonomycin A-induced positive inotropic action was partly inhibited by pretreatment with pindolol, however gradual shortening of the ventricular wall length was still observed. A positive chronotropic action induced by lonomycin A was inhibited by pindolol pretreatment in vivo. On the other hand, lonomycin A elicited a negative chronotropic effects in the isolated guinea-pig right atrium, concomitantly increasing resting tension. These results suggest that lonomycin A alone produces peripheral vascular dilation and effects cardiac functions, which are in turn modified by lonomycin A-induced cathecholamine release from nerve terminals.

Animals↗