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H Azuma

Publications and source records attributed to H Azuma.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effects of absorption enhancers on cytoskeletal actin filaments in Caco-2 cell monolayers.

Histomorphological changes of actin filaments, intracellular levels of calcium ion, and amount of released lactate dehydrogenase (LDH) were examined, in order to elucidate the mechanism of action of three absorption enhancers, i.e., sodium caprate (Cap-Na), sodium deoxycholate (Deo-Na), and dipotassium glycyrrhizinate (Grz-K), using Caco-2 cell monolayers. The structure of actin filaments in microvilli was slightly modified by 0.5 %(w/v) Grz-K and was significantly changed by 0.2 %(w/v) Cap-Na, 0.05 %(w/v) Deo-Na, and 0.0015 %(w/v) ionomycin. All of the enhancers, except Grz-K, induced significantly histomorphological changes in the actin filaments on the middle depth and basal side of the cells. Furthermore, the altered structure of the actin filaments in the monolayers was restored after removal of the Cap-Na, Grz-K and ionomycin, but not Deo-Na. Intracellular levels of calcium ion increased in the following order: ionomycin = Cap-Na > Deo-Na. However, the intracellular calcium ion levels decreased by treatment with Grz-K. The changes in transepithelial electric resistance (TEER) at the initial stage of treatment with all enhancers correlated with intracellular calcium ion levels. These results suggest that one of the mechanisms by which these agents exert absorption-enhancing activity involves structural alterations in the cytoskeletal actin filaments which are provoked by changes in intracellular calcium ion levels. Only the monolayers which were treated with 0.05 %(w/v) Deo-Na released a significant amount of LDH and irreversibly altered the structure of actin filaments, thus indicating that Deo-Na might affect the actin filaments not only by increasing intracellular calcium ion level but also by other, presently unknown factors.

Actins↗
PubMed1998

Morphology and distribution of nerve endings in the human triangular fibrocartilage complex.

We studied the morphology and distribution of nerve endings in the human triangular fibrocartilage complex using both silver staining and immunohistochemical staining using a protein specific to nerve fibres. Free nerve endings were found in the ulnar side of the triangular fibrocartilage complex, especially in the ulnar collateral ligament, meniscus homologue and the adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc. Meissner's and Krause's corpuscles were observed in the ulnar collateral ligament and meniscus homologue. The fact that free nerve endings were observed in the meniscus homologue and adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc suggests that this disc may be a source of wrist pain. The presence of nerve end bulbs in the triangular fibrocartilage complex also suggests a possible role for corpuscles as mechanoreceptors.

Adult↗
PubMed1998

M3-type muscarinic receptors predominantly mediate neurogenic quick contraction of bovine ciliary muscle.

1. The present experiments were designed to investigate which subtypes of muscarinic receptors are involved in the neurogenic quick contraction of bovine ciliary muscle in connection to quick eye focal accommodation. 2. Transmural electrical stimulation (TES) produced a transient contraction, which was abolished in the presence of 3 x 10(-7) M tetrodotoxin and 10(-6) M atropine, but greatly augmented by 3 x 10(-7) M physostigmine. 3. The exogenously applied acetylcholine (ACh: 10(-9) to 3 x 10(-6) M) produced a concentration-dependent contraction, which was competitively antagonized by 10(-6) M atropine and augmented by 3 x 10(-7) M physostigmine, but unaffected by 3 x 10(-7) M tetrodotoxin. 4. The magnitude and time to peak of the maximal contraction produced by TES were significantly greater (1267.5 +/- 86.0 mg, P < 0.005) and shorter (9.0 +/- 0.2 sec, P < 0.005) than corresponding values (97.0 +/- 9.9 mg and 20.3 +/- 2.1 sec, respectively) of the phasic contraction caused by exogenously applied 10(-5) M ACh, at which concentration the agonist caused the maximal contraction. The velocity (140.6 +/- 7.8 mg/sec) of the transient contraction caused by TES was approximately 28-fold greater than that of the phasic contraction caused by ACh (5.1 +/- 0.9 mg/sec). 5. The contractions produced by TES were greatly attenuated by 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) as an M3 antagonist and slightly by pirenzepine as an M1 antagonist (20.2 +/- 7.9% inhibition at the highest concentration), but not by methoctramine (MET) as an M2 antagonist. The IC50 value (-log M) for 4-DAMP was determined to be 7.17 +/- 0.14. 6. Scatchard plot analysis of [3H]-quinuclidinylbenzilate (QNB) binding revealed that the binding sites constituted a single population with a Kd of 31.2 +/- 0.8 pM and a Bmax of 895.5 +/- 93.2 fmol/mg protein. The activity in inhibiting [3H]-QNB binding was most potent with 4-DAMP (-log Ki = 7.98 +/- 0.02), but less potent with pirenzepine (-log Ki = 6.43 +/- 0.04) and MET (-log Ki = 7.32 +/- 0.16). 4-DAMP was approximately 35- and 5-fold more potent than pirenzepine and MET in terms of -log Ki values, respectively, suggesting the predominant localization of M3 receptor subtypes in the bovine ciliary muscle membrane. 7. These results suggest that TES produces a neurogenic quick contraction of the bovine ciliary muscle, which would be mediated mainly by ACh released from the intramural nerve terminals and subsequent excitation of M3 receptor subtypes localized on the ciliary muscle cells, and that neurogenic quick contraction of the ciliary muscle is possibly involved in part in eye focal accommodation.

Animals↗
PubMed1998

Mutational analysis of the N-ras gene in acute lymphoblastic leukemia: a study of 125 Japanese pediatric cases.

A point mutation of the N-ras gene is one of the known genetic alterations identified in patients with acute lymphoblastic leukemia (ALL), but its clinical importance is still controversial. Using polymerase chain reactions, we examined codons 12, 13 and 61 of this gene in 125 Japanese childhood ALL patients (64 common-ALL, 22 pre-B-ALL, 33 T-ALL, 2 B-ALL, 3 undifferentiated ALL, and 1 unclassified ALL) including 9 relapsed patients. An N-ras point mutation was observed in 14 (11%) patients (9 common-ALL, 3 T-ALL, and 2 undifferentiated ALL; 13 patients at diagnosis and 1 at relapse). The patients with undifferentiated ALL harbored an N-ras mutation at a significantly higher rate. However, no correlation was found between the presence of an N-ras mutation and sex, age, or white blood count. There was no significant difference in the event-free survival rate between 13 fresh patients with an N-ras mutation and 103 patients with a wild-type configuration. The N-ras mutation was present in about 10% of childhood ALL cases but it did not have a prognostic impact. The sequence analyses revealed that the majority of the patients (13/14) had an N-ras mutation of a G to A transition. This finding was consistent with previous reports on N-ras mutations in acute leukemias in which the incidence of a G to A mutation was significantly higher in ALL than in myeloid malignancies.

Child↗
PubMed1998

A cross-national study of self-evaluations and attributions in parenting: Argentina, Belgium, France, Israel, Italy, Japan, and the United States.

This study investigated and compared ideas about parenting in Argentine, Belgian, French, Israeli, Italian, Japanese, and U.S. mothers of 20-month-olds. Mothers evaluated their competence, satisfaction, investment, and role balance in parenting and rated attributions of successes and failures in 7 parenting tasks to their own ability, effort, or mood, to difficulty of the task, or to child behavior. Few cross-cultural similarities emerged; rather, systematic culture effects for both self-evaluations and attributions were common, such as varying degrees of competence and satisfaction in parenting, and these effects are interpreted in terms of specific cultural proclivities and emphases. Child gender was not an influential factor. Parents' self-evaluations and attributions help to explain how and why parents parent and provide further insight into the broader cultural contexts of children's development.

Adult↗
PubMed1998

Differences between proximal and distal portions of the male rabbit posterior urethra in the physiological role of muscarinic cholinergic receptors.

1. The aim of the present study was to elucidate functional differences between embryologically different portions of the posterior urethra of male rabbits in response to muscarinic acetylcholine receptor (mAChR) stimulation using in vitro isometric tension experiments and radioligand binding studies. 2. In the in vitro isometric tension experiments, carbachol, produced a dose-dependent contraction of the proximal portion under the resting state, but did not change the basal tone of the distal portion. Contraction of the proximal portion by 10(-5) M noradrenaline (NA) was dose-dependently enhanced by carbachol either in the presence or absence of NG-nitro-L-arginine (NOARG). In contrast, carbachol induced relaxation of the distal portion contracted by 10(-5) M NA, which was reversed to dose-dependent contraction in the presence of NOARG. 3. Both portions of the urethra had a similar number of [3H]-quinuclidinyl benzilate ([3H]-QNB) binding sites (195.3+/-74.1 fmols mg(-1) protein for the proximal portion and 146.5+/-8.5 fmols mg(-1) protein for the distal portion) with similar affinities (115.0+/-45.4 pM for the proximal portion and 79.9+ 2.9 pM for the distal portion). 4. The concentration-response curves to carbachol in both portions were shifted to the right in a parallel manner in the presence of pirenzepine (an M1 antagonist), 11-[[2-[(diethylamino)methyl]-1-piperidinyl] acetyl]-5, 11-dihydro-6H-pyrido-2,3-b)-(1,4)-benzodiazepin-6-one (AFDX-116, an M2 antagonist) and 4-diphenyl-acetoxy-N-methyl-piperidine (4-DAMP, an M1/M3 antagonist). The pA2 values for pirenzepine, AFDX-116 and 4-DAMP were 7.5+/-0.1, 7.2+/-0.02 and 9.3+/-0.1 respectively for the contraction of the proximal portion, and 7.2+/-0.1, 7.1+/-0.2 and 9.1+/-0.2, respectively for the relaxation of the distal portion. 5. In conclusion mAChR subtypes distribute in a similar fashion throughout the length of the male rabbit posterior urethra with the discrepant responses to carbachol attributable to the differential involvement of the NO pathway in mAChR-generated reactions.

Animals↗
PubMed1998

Endogenous asymmetrical dimethylarginine and hypertension associated with puromycin nephrosis in the rat.

1. The present experiments were designed to investigate the role of asymmetrical NG,NG-dimethyl-L-arginine (ADMA) in causing hypertension associated with the focal and segmental glomerulosclerosis (FSGS) produced by a single bolus of puromycin aminonucleoside (PAN) and successive injection of protamine for 7 days in rats which had undergone unilateral nephrectomy. 2. After the unilateral nephrectomy, and administering PAN and protamine, histological examinations of the kidney revealed a typical FSGS, that is, evident abnormalities including segmental mesangial proliferation, obliteration of glomerular capillary lumens and adhesions between the glomerulus and Bowman's capsule could be observed. Changes in the glomerular epithelial cells consisted of the swelling with bleb formation. 3. In the FSGS rats, urine volume and urinary protein were significantly (P<0.05 and P<0.005) increased throughout 4-week experimental period, while the creatinine clearance was significantly (P<0.005) and transiently decreased, and recovered 4 weeks later. These changes were associated with the sustained elevation of the systolic blood pressure. 4. ADMA levels in aortic endothelial cells, plasma and urine were significantly (P<0.05 and P<0.005) increased in the FSGS rats, but the level in the kidney remained unchanged. 5. The basal level and net production of cyclic GMP in the aortic vessel wall with endothelium when stimulated by norepinephrine and acetylcholine were significantly (P<0.05 and P<0.01) attenuated in the FSGS rats. 6. There were significant and positive correlations between systolic blood pressure (y) and ADMA levels (x) in endothelial cells (y=4.43x+122.2, r=0.979, P<0.0001), plasma (y=0.10x+71.9, r=0.921, P<0.001) and urine (y=0.48x+126.9, r =0.699, P<0.005), but not significant in the kidney (y=0.06x+102.7, r=0.252, NS). 7. These findings suggest that ADMA as an endogenous inhibitor of NO synthesis may play an important role for the pathogenesis in the hypertension associated with the experimental FSGS in the rat.

Animals↗
PubMed1998

Lymphotactin: a key regulator of lymphocyte trafficking during acute graft rejection.

The attraction of leucocytes to allografts is essential for rejection. The process is controlled by chemokines. In order to clarify the role of lymphotactin (a cytokine that represents a novel branch of the chemokine superfamily) in regulating leucocyte trafficking during graft rejection, we used rat renal transplantation models to examine its gene expression and the distribution of lymphotactin-expressing cells in renal grafts. Lymphotactin mRNA was upregulated strongly in acutely rejecting renal allografts. The mRNA was undetectable in isografts, chronically rejecting renal allografts or normal kidney. Once lymphotactin was expressed, large numbers of infiltrating lymphocytes were seen. Moreover extended studies demonstrated that in cultured rat spleen cells the expression of lymphotactin mRNA was markedly induced by phytohaemagglutinin (PHA) or phorbol myristate acetate (PMA), and such induction was inhibited by the immunosuppressive drugs FK506 and cyclosporin. Collectively, these observations provide new evidence demonstrating that lymphotactin is a key regulator of lymphocyte motility and adhesiveness during acute allograft rejection. FK506 and cyclosporin inhibition of lymphotactin expression is likely to represent an important molecular mechanism of the action of the drugs.

Acute Disease↗
PubMed1998

Involvement of angiotensin II receptor subtypes during testicular development in rats.

Expression of testicular angiotensin II (AT2) receptors in Sprague-Dawley rats at various stages of development (1 and 5 days, 2, 3, 4 and 7 weeks postnatal) were studied by in vitro autoradiography and Northern blot analysis. The receptors were labelled with 125I-[Sar1, Ile8]AT2 and differentiated into two subtypes according to their susceptibility to AT1 (losartan, 5 microM) or AT2 (PD123319, 5 microM) antagonist. Total AT2 receptor binding in the testis was highest at 1 day of age (8.12 +/- 0.35 fmol/mg protein, mean +/- secEM, n = 8) and decreased gradually thereafter (5 days: 6.9 +/- 0.41, 2 weeks: 2.85 +/- 0.10, 3 weeks: 1.64 +/- 0.19, 4 weeks: 0.76 +/- 0.09, 6 weeks: 0.77 +/- 0.09 fmol/mg protein, n = 8-11). AT2 receptor binding was strikingly abundant in 1-day-old rat testis (6.98 +/- 0.34 fmol/mg protein), while considerably less AT1 receptor binding (1.46 +/- 0.19 fmol/mg protein) was observed. The relative amounts of each subtype did not change for the first 3 weeks but the 4-week-old rat testis contained almost exclusively AT1 receptors (0.63 +/- 0.05 fmol/mg protein). Northern blot analysis showed that mRNA expression of both AT1 and AT2 types decreased with age. Microscopic emulsion autoradiography was undertaken to clarify the localization of binding. At 10 days of age, both AT1 and AT2 receptors were present in the interstitial area, whereas seminiferous tubules contained mainly AT2 receptors. At 7 weeks of age, no significant binding was observed in the seminiferous tubule and the interstitial area contained AT1 receptors exclusively. These results demonstrate expression of AT2 receptors in the rapidly growing testis and suggest that change in the levels of AT2 receptor subtypes may be relevant to development and/or growth of the testis.

Angiotensin II↗
PubMed1998

[Intravesical BCG therapy for superficial bladder cancer].

Intravesical instillation of Tokyo 172 strain bacillus Calmette-Guerin (BCG) after transurethral resection of bladder tumor (TUR-Bt) was applied to 35 patients with superficial bladder cancer. The patients received 80 mg of BCG in 40 ml saline infused into the bladder once a week for 6 weeks. Actuarial non-recurrence rates for all 35 patients were 81.7% and 58.4% at one and two years after the BCG therapy, respectively. The recurrence of the bladder cancer after the BCG therapy was observed in 12 patients 3-27 months later. Seven patients received an additional course of BCG instillation, and 6 (86%) showed no further recurrence. Thus, the overall success rate of 2 cycles of BCG instillation was 83% (29 of 35 patients). Moreover, in some cases intravesical BCG instillation was effective for recurrent superficial bladder cancer after intravesical instillation of anti-cancer agents and prolonged the period until recurrence. The progression rate was only 5% (2 of 35 patients). These results suggest that intravesical BCG therapy for superficial bladder cancer helps prevent disease progression.

Administration, Intravesical↗
PubMed1998

[Epidermoid cyst of the scrotum: a case report].

A 52-year-old male visited our department for a painless swelling from the right side of the anus to the right scrotum that he first noticed 5 years earlier. Palpation revealed a small fist-sized elastic solid mass with a smooth surface from the central area to the inferior pole of the right scrotum. This mass was clearly demarcated from the contents of the scrotum and not adherent to the scrotal skin. A diagnosis of a tumorous lesion in the scrotum was made, and the tumor was resected. Histopathological examination demonstrated a scrotal epidermoid cyst. To our knowledge, this is the 17th case reported in Japan.

Epidermal Cyst↗
PubMed1998

[Idiopathic adrenal hemorrhage: a case report].

A 77-year-old man with a low grade fever persisting for 30 days consulted a local physician. A computed tomographic scan of the abdomen showed a mixed density mass on the left adrenal gland. He was referred to our hospital for further examination. Hormonal assay demonstrated a slightly high level of noradrenalin in the serum (18 pg/ml) and vanillyl mandelic acid in the urine (6.2 ng/ml). Magnetic resonance imaging revealed a heterogeneous mass lesion 3 cm in diameter with a high signal intensity on both T1 and T2 weighted images. Angiography showed a hypovascular mass in the supra-renal region suggesting an adrenal tumor or malignancy. Left adrenalectomy combined with en bloc nephrectomy was performed because of severe adhesion. Histologic evaluation showed hematoma without malignant cells due to idiopathic adrenal hemorrhage.

Adrenal Gland Diseases↗
PubMed1997

Cellular and molecular predictors of chronic renal dysfunction after initial ischemia/reperfusion injury of a single kidney.

BACKGROUND: Initial ischemia/reperfusion injury occurring secondary to organ retrieval, storage, and transplantation has been associated with late renal allograft deterioration and failure. In addition, there is an apparent synergy, reported in several clinical series, between the initial injuries of ischemia/reperfusion and acute rejection; the long-term results of graft survival are significantly deceased after both events in combination as compared with either alone or if no such episodes occur. METHODS: In the present study, we examined patterns of proteinuria, cellular infiltration, cytokine expression, and glomerulosclerosis over time in Lewis and Fischer 344 rats after 45 min of warm ischemia of a single kidney and with or without contralateral nephrectomy. Both early (4 hr to 7 days) and late (2-52 weeks) events were studied serially in the affected kidneys morphologically, by immunohistology and by reverse transcriptase polymerase chain reaction. RESULTS: Intercellular adhesion molecule 1, endothelin, and major histocompatibility complex class II expression were up-regulated within 2 to 5 days after injury; T cells and macrophages increased transiently. Proteinuria developed after approximately 8 weeks only in animals bearing a single injured kidney, and not in those with a retained native organ. Progressive morphological changes occurred after 16 weeks, including glomerulosclerosis, arterial obliteration, and interstitial fibrosis. After a period of relative quiescence, expression of intercellular adhesion molecule 1 again increased in relation to progressive macrophage infiltration and their associated products, particularly, interleukin 1, tumor necrosis factor-alpha, transforming growth factor-beta, and inducible nitric oxide synthase. Monocyte chemotactic protein 1 was intensely up-regulated by 24 weeks, coincident with a dramatic rise in this infiltrating population. These changes remained virtually at baseline in animals with a retained native kidney. CONCLUSIONS: These data imply that chronic injury after significant initial ischemia and reperfusion occurs when there is already a 50% renal mass reduction, but not when two kidneys remain in place. Permanent nephron loss resulting from such an insult could account for this phenomenon. Early ischemia and reperfusion, if severe enough in a single kidney, may be an important antigen-independent risk factor for later renal deterioration and failure. In the context of a renal allograft, it may contribute to chronic rejection.

Animals↗
PubMed1997

Nephron mass modulates the hemodynamic, cellular, and molecular response of the rat renal allograft.

Functioning nephron mass has recently been implicated as a risk factor for development of chronic "rejection" of kidney allografts. Reductions in nephron number below 50% may induce glomerular hypertension and hyperfiltration in surviving units, which in turn lead to graft injury. In the present study, which extends and amplifies our previous investigations, cellular and molecular characteristics of single allografts from F344 donors in bilaterally nephrectomized LEW recipients, our standard experimental model of chronic renal allograft dysfunction, were compared with allografts from recipients where total renal mass was reduced (by ligating branches of the graft renal artery) or restored to normal levels by transplanting or retaining a second kidney. Our findings in this study confirm that progressive proteinuria and structural injury in recipients of single allografts were accentuated in grafts with reduced mass but virtually absent in rats with increased kidney mass. A striking observation was that patterns of cell surface molecule expression, cellular infiltration, and expression of all T cell- and macrophage-associated products studied were all markedly modulated by changes in renal mass. Moreover, several molecules that are up-regulated before evidence of graft injury are down-regulated by providing increased renal mass. These data show that the quantity of functioning renal mass is not only an important independent determinant of the tempo and intensity of chronic renal allograft failure, but also a potent modulator of fundamental cellular and molecular components of a complex process. This phenomenon involves antigen-dependent and antigen-independent elements that ultimately result in chronic allograft failure.

Animals↗
PubMed1997

Molecular pathogenesis of type I congenital plasminogen deficiency: expression of recombinant human mutant plasminogens in mammalian cells.

We previously reported the genetic abnormality in a Japanese family with type I congenital plasminogen deficiency caused by a Ser572 to Pro572 mutation. To characterize the molecular pathogenesis of the disease in this family, we expressed recombinant human wild-type and mutant (rS572P) plasminogens in COS-1 cells. Activation-resistant wild-type and mutant plasminogen stable transfectants in CHO-K1 cells also were established. Transient transfection and metabolic labeling experiments followed by immunoprecipitation analysis showed that the mutant plasminogen was secreted from COS-1 cells in reduced amounts, compared with the wild type. Endo H digestion of the wild-type and mutant plasminogen showed no shift in their migrations on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, indicating that both contain complex type oligosaccharide structures and could therefore be secreted. Furthermore, the secretion of activation-resistant mutant plasminogen was significantly reduced. Pulse-chase experiments and Northern blot analysis showed that the impaired secretion of the mutant plasminogen was the consequence of the accumulation of the mutant protein inside the cells but not of reduced plasminogen mRNA. Immunocytochemical staining of stable transfectants also revealed that CHO-K1 cells expressing the activation-resistant mutant plasminogen stained mainly in the perinuclear area, suggesting delayed processing of the mutant protein in the intracellular transport pathway. We conclude that the impaired secretion of mutant plasminogen, due to intracellular accumulation, is the molecular pathogenesis of type I congenital plasminogen deficiency caused by a Ser572 to Pro572 mutation.

Animals↗
PubMed1997

A possible role of endogenous inhibitor for nitric oxide synthesis in the bovine ciliary muscle.

The present experiments were designed to investigate the possible role of endogenous methylarginine derivatives such as NG-monomethyl-L-arginine, asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine for the nitric oxide synthesis in the bovine ciliary muscle. The contents of asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine in the bovine ciliary muscle were determined to be 370.2 +/- 27.6 (n = 5) and 182.4 +/- 22.9 (n = 5) pmoles g-1 wet weight, respectively by means of the automated high-performance liquid chromatography. NG-Monomethyl-L-arginine was below the assay limits. On the basis of the total tissue water content (0.792 +/- 0.006 ml g-1 wet weight, n = 14), the concentrations of asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine were tentatively estimated to be (4.7 +/- 0.3) x 10(-7) M (n = 5) and (2.3 +/- 0.3) x 10(-7) M (n = 5), respectively. A23187 (10(-7)-3 x 10(-4) M) produced a concentration-dependent relaxation of the ciliary muscle strips which had been contracted with 10(-5) M carbachol. Authentic asymmetrical NG,NG-dimethyl-L-arginine (3 x 10(-6)-3 x 10(-4) M), but not symmetrical NG,N'G-dimethyl-L-arginine (3 x 10(-4) M), inhibited the 10(-6) M A23187-induced relaxation in a concentration-dependent manner. The inhibition with asymmetrical NG,NG-dimethyl-L-arginine (10(-4) M) was reversed by an addition of 3 x 10(-3) M L-arginine, but not by 3 x 10(-3) M D-arginine. The A23187 (10(-6) M)-induced relaxation was enhanced by 3 x 10(-3) M L-arginine or superoxide dismutase (50 U ml-1), whereas it was inhibited by carboxy-PTIO (3 x 10(-4) M), a scavenger of nitric oxide, or methylene blue (10(-5) M), an inhibitor of guanylate cyclase. The carbachol-induced contraction was enhanced by asymmetrical, NG,NG-dimethyl-L-arginine (10(-5) M) and inhibited by 3 x 10(-3) M L-arginine. Any effect of prostanoid formation during the A23187-induced relaxation was ruled out by using indomethacin (10(-5) M). Sodium nitroprusside (10(-5) M), a donor of nitric oxide, also produced a relaxation, which was inhibited by methylene blue (10(-5) M) or carboxy-PTIO (3 x 10(-4) M) and was augmented by superoxide dismutase (50 U ml-1), but unaffected by asymmetrical NG,NG-dimethyl-L-arginine (3 x 10(-4) M) or L-arginine (3 x 10(-3) M). These results lead us to speculate that the nitric oxide synthesized endogenously from L-arginine may play a role for mediating relaxation of the bovine ciliary muscle and that the endogenous asymmetrical NG,NG-dimethyl-L-arginine may be involved in inhibiting the biosynthesis of nitric oxide when there are increased intracellular concentrations of the methylarginine under certain circumstances.

Animals↗
PubMed1997

Smooth muscle cell proliferation, elastin formation, and tropoelastin transcripts during the development of intimal thickening in rabbit carotid arteries after endothelial denudation.

Extracellular matrix formation and smooth muscle cell proliferation are two major factors contributing to the development of intimal thickening after arterial injury. We investigated the elastin formation, tropoelastin transcripts, and proliferation of smooth muscle cells during the development of intimal thickening in rabbit carotid arteries after balloon endothelial denudation. Tropoelastin transcripts, identified by in situ hybridization using a digoxigenin-labeled probe, and elastin staining in the thickened intima were minimal 1 week after endothelial denudation when smooth muscle cell proliferation appeared throughout the thickened intima. A strong signal for tropoelastin transcripts was seen in the basal layer of the thickened intima 2 weeks after endothelial denudation, and then in the surface layer of the thickened intima 4 weeks after endothelial denudation. Immunohistochemistry for proliferating cell nuclear antigen and Ki-67, both markers for proliferating cell nuclei, showed that tropoelastin transcripts and elastin formation increased when smooth muscle cells enter quiescence after the end of the proliferative phase in the intima. Our findings strongly suggest that elastin synthesis and smooth muscle cell proliferation are tightly regulated during the repair of arterial wall injury.

Animals↗