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Biomedical subjects

A Forman

Publications and source records attributed to A Forman.

At least 37 records · Page 2Linked to original sources
PubMed1996

The effect of oophorectomy on mechanical properties of rabbit cerebral and coronary isolated small arteries.

OBJECTIVE: Our purpose was to study the effect of oophorectomy on the passive and active mechanical characteristics of rabbit small cerebral and small coronary arteries. STUDY DESIGN: Ring preparations of small cerebral and small coronary arteries from rabbits that had undergone oophorectomy and sham operation were mounted on myographs 6 weeks after operation. Experiments were performed as follows. (1) concentration-response relations for vasopressin (10(-11) to 10(-7) mol/L), U46619 (10(-10) to 10(-6) mol/L), 5-hydroxytryptamine (10(-7) to 10(-5) mol/L), and endothelin (10(-13) to 10(-7) mol/L); (2) relaxing effects of acetylcholine (10(-8) to 10(-4) mol/L); (3) length-tension relations after addition of high potassium (124 mmol/L), vasopressin (10(-7) mol/L), and a mixture composed of potassium (124 mmol/L), vasopressin (10(-7) mol/L), and prostaglandin F 2 alpha (10(-5) mol/L); (4) calculation of vessel morphologic features and determination of hydroxyproline as a measure of collagen content. RESULTS: Oophorectomy did not influence basal tone, relaxant effects of acetylcholine, vessel morphologic features, elastic characteristics, or hydroxyproline content of the vessels. However, in cerebral arteries at a normalized lumen diameter, oophorectomy induced a marked increase in the force development after stimulation with agonists but not after depolarization with high potassium. The reason for this was a leftward shift in the active length-tension curves (vasopressin activation). In coronary arteries none of these changes were seen after oophorectomy. CONCLUSION: These data demonstrate that withdrawal of ovarian hormones changes the position of the active length-tension curve for pharmacomechanical but not electromechanical coupling of small cerebral arteries without interference with the elastic characteristics of these vessels.

Acetylcholine↗
PubMed1996

The incidence of fallopian tube patency after transcervical resection of the endometrium including rollerball diathermy to the tubal ostia.

OBJECTIVE: To evaluate the incidence of tubal patency as well as the shape of the endometrial cavity after transcervical resection of the endometrium. DESIGN: An open observational trial. SETTING: The obstetrics and gynecology unit at a district hospital in Norway. PATIENTS: Fifty consecutive patients who had undergone treatment for menorrhagia and metrorrhagia by resection of the endometrium and coagulation of the tubal ostium were included in the study. INTERVENTION: A hysterosalpingogram was performed with a semistiff catheter and injection of 20 mL contrast dye 5 to 12 months after transcervical resection of the endometrium and fibroids. MAIN OUTCOME MEASURES: Tubal patency and uterine cavity morphology. RESULTS: Forty-four patients showed total occlusion of the fallopian tubes, and the uterine cavity showed fibrosis and narrowing of the cavity. Three patients showed bilateral and three patients unilateral tubal patency. CONCLUSION: Shrinkage and fibrosis of the uterine cavity occur after endometrial resection. A significant number of women after transcervical resection of the endometrium have patient tubes (13%) despite coagulation of the tubal ostia.

Adult↗
PubMed1996

The relationship between preoperative endometrial thickness, the anteroposterior diameter of the uterus and clinical outcome following transcervical resection of the endometrium.

The objective of this study was to identify whether the endometrial thickness, or the anteroposterior diameter of the uterus as assessed by transvaginal ultrasonography (TVS), could be used to predict the clinical outcome following transcervical resection of the endometrium (TCRE). An open observational trial was carried out, involving 195 consecutive patients undergoing TCRE, 188 of whom completed follow-up. The patients were examined by TVS preoperatively, and then 6 weeks, 6 months and 1 year following TCRE. In all examinations, endometrial thickness, the anteroposterior diameter and residual endometrium, uterine morphology and the clinical outcome as measured by pain reduction, bleeding index and amenorrhea were assessed. Patients with a preoperative endometrial thickness of 8 mm or less had a higher rate of amenorrhea after 1 year than patients with an endometrial thickness exceeding 8 mm. Outcome did not relate to the histological phase of the endometrium obtained during resection. Neither the uterine anteroposterior diameter, or the presence of submucous fibroids, had any influence on the clinical outcome. Cavity fluid was observed in some cases but was not always associated with symptoms. Residual endometrium could be detected by TVS in 38% of the women after 1 year, but the vast majority of these patients reported a satisfactory outcome from the procedure. We conclude that the size of the anteroposterior diameter does not affect the clinical outcome of TCRE, whilst the preoperative endometrial thickness does have a significant impact on the likelihood of achieving amenorrhea after 1 year. The data suggest that TCRE should preferably be performed when the endometrium is at its thinnest and that there may be a useful role for agents that produce endometrial atrophy prior to surgery.

Adult↗
PubMed1996

Detection of antibodies against foot-and-mouth disease virus using a liquid-phase blocking sandwich ELISA (LPBE) with a bioengineered 3D protein.

A liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA-3D) was developed to detect specific antibodies to the 3D protein in sera from foot-and-mouth disease (FMD) virus (FMDV)-infected animals. The assay uses a nonstructural 3D recombinant protein and two polyclonal antisera, one for capture (bovine) and the other for detector (guinea pig). The specificity of the assay was demonstrated by negative results with 101 sera of cattle from the FMD-free zone in Argentina and with bovine and porcine sera raised against various RNA and DNA viruses. The ELISA-3D was able to detect antibodies in cattle after natural or experimental infection with FMDV of A, O, or C types as early as 5 days postinfection and at later stages in persistently infected animals. Comparison of the results with those obtained with the routinely used agar gel immunodiffusion test and a previously described ELISA, both employing a partially purified virus-infection-associated antigen, shows that the ELISA-3D is highly sensitive and specific and gives reproducible results. Its use as a tool for monitoring viral activity and for certification of FMDV-free animals is recommended.

Animals↗
PubMed1996

Effects of ovariectomy on mechanical properties and collagen content in rabbit lower urinary tract smooth muscle.

Fourteen female rabbits underwent ovariectomy or were sham-operated six weeks before investigation. Detrusor and urethral strips (longitudinal and circular urethral muscle fibers were studied separately) were prepared and length-tension relations studied in organ baths experiments. In addition, the specimens were examined for collagen content. Maximal active tension in the detrusor, longitudinal and circular urethral preparations, determined as the response to K+ (124mM), was reached when the length of the strips was 178 +/- 8% (n = 7), 153 +/- 9% (n = 5), and 127 +/- 5% (n = 7) of the resting length, respectively. Ovariectomy did not alter the length for development of maximal active tension. In detrusor strips, ovariectomy caused a significant increase in maximal active tension from 39 +/- 7 mN (sham-operated rabbits) to 79 +/- 11 mN (p < 0.01), despite an unchanged relative amount of smooth muscle. The maximal active tension produced in the urethra was lower (15-25 mN) than in the detrusor, and not significantly affected by ovariectomy. Approximately 40% of the dry defatted tissue weight of the detrusor consisted of collagen, whereas corresponding value in the urethra was 50-60%. Ovariectomy had no effect on tissue collagen concentrations. In conclusion, ovariectomy for six weeks did not affect the passive mechanical properties or the collagen concentration in rabbit lower urinary tract smooth muscle, but increased the responsiveness of the detrusor muscle to K+ (124 mM).

Animals↗
PubMed1996

Phase II study of docetaxel in patients with epithelial ovarian carcinoma refractory to platinum.

We analyzed the efficacy and toxicity of docetaxel in patients with ovarian cancer who failed previous chemotherapy with platinum. Fifty-five patients with measurable ovarian cancer were entered in this Phase II study at The University of Texas M. D. Anderson Cancer Center. Treatment consisted of 100 mg/m2 docetaxel given i.v. every 3 weeks. Because of hypersensitivity reactions, premedication with steroids and antihistamine was initiated during the study. Twenty-two (40%) patients responded (there were 3 complete responders and 19 partial responders). Twenty-one (38%) patients had stable disease. The median survival was 10 months. The main toxicity was neutropenia (98% of patients), with 13 episodes of neutropenic fever. Cumulative fluid retention was the main reason for dose modification and required a combination of diuretics and steroids for palliation. Other side effects were alopecia (100%); anemia (87%); dermatitis (67%); gastrointestinal disorders (53%); stomatitis (49%); neurotoxicity (45%); excessive lacrimation (33%); and hypersensitivity reactions (11%), which in one case were life threatening (loss of consciousness, fluid resuscitation). Docetaxel as a single agent proved to be active in heavily pretreated ovarian cancer patients but is associated with significant side effects. Objective toxicity consisted mainly of neutropenia and fluid retention. Neutropenia was dose limiting and required therapy with granulocyte colony-stimulating factor. Fluid retention was improved but not eliminated by diuretics and corticosteroids. Additional studies of docetaxel in ovarian carcinoma are indicated to define the activity in relation to paclitaxel and in platinum combination therapy.

Adult↗
PubMed1995

Changes in amino acids, ammonium, and coagulation factors after transcervical resection of the endometrium with a glycine solution used for uterine irrigation.

OBJECTIVE: Transcervical resection of the endometrium with the use of 1.5% glycine for irrigation is associated with postoperative nausea in some patients. This could be because of hyponatremia or toxic effects of glycine and its metabolites. Moreover, 1.5% glycine is hypoosmolar, and hemolysis and fibrinolysis are possible. Changes in plasma factors related to these potential complications of transcervical resection of the endometrium were measured. STUDY DESIGN: In 101 patients undergoing transcervical resection of the endometrium sodium, ammonium, and coagulation factors were measured preoperatively and postoperatively at intervals. In the initial 30 patients glycine and 28 other amino acids were measured at the same intervals. The results were correlated with the patients' clinical status and operative parameters. RESULTS: Glycine and nine other amino acids and ammonia showed increased postoperative plasma levels; these changes were correlated with the absorption of the irrigating glycine solution and the development of hyponatremia. Minor activation of fibrinolysis and hemolysis was also seen. CONCLUSION: Nausea after transcervical resection of the endometrium with 1.5% glycine for irrigation may be partly explained by toxic effects of glycine and its secondary metabolites in addition to the effects of water intoxication and hyponatremia. Minor, clinically insignificant changes in the coagulation system may also occur. Studies on alternatives to glycine for creation of near-isotonic irrigating solutions are encouraged.

Adult↗
PubMed1995

Angiotensin-converting enzyme activity and contractile effects of angiotensin I and II in human uteroplacental arteries.

OBJECTIVE: Our purpose was to study local angiotensin-converting enzyme activity and the mechanical effects of angiotensin I and II in human uteroplacental arteries. STUDY DESIGN: Angiotensin-converting enzyme activity was measured by a simple radioimmunoassay with tritiated benzoyl-glycyl-glycyl-glycine as substrate in isolated human intramyometrial arteries from nonpregnant (n = 8) and term pregnant women (n = 8) and placental (n = 8) stem villous arteries. Moreover, in these vessels the mechanical effects of angiotensin I and II were investigated in organ bath experiments. Endothelium-intact and endothelium-denuded arteries were used, and the integrity of the endothelium was examined by histologic studies. RESULTS: The activity of angiotensin-converting enzyme ranked the intramyometrial arteries from pregnant women >> intramyometrial arteries from nonpregnant women > fetal stem villous arteries. Angiotensin-converting enzyme activity was unaffected by removal of the endothelium. Angiotensin II 10(-5) mol/L produced contractile responses in the intramyometrial arteries without significant differences between arteries from nonpregnant and pregnant women. In fetal stem villous arteries the effects of angiotensin II 10(-5) mol/L were less pronounced. As for angiotensin II, the contractile responses to angiotensin I 10(-5) mol/L showed marked development of tachyphylaxis. In the endothelium-denuded preparations the contractile responses to angiotensin I 10(-5) mol/L were significantly enhanced in intramyometrial arteries from nonpregnant women but remained unchanged in intramyometrial arteries from pregnant women and in fetal stem villous arteries. In all preparations pretreatment with captopril or perindopril (10(-5) mol/L) markedly reduced angiotensin-converting enzyme activity, whereas no effects were observed on the contractile responses to angiotensin I. Saralasin 10(-5) mol/L completely abolished the contractile responses to angiotensin I and II. CONCLUSION: Local angiotensin-converting enzyme activity in human intramyometrial arteries seems to be markedly increased during pregnancy and shows marked differences between maternal and fetal uteroplacental arteries. High concentrations of angiotensin I may imply direct effects on the angiotensin II receptor independent of the local angiotensin-converting enzyme activity.

Angiotensin I↗
PubMed1995

Calcium channel blockade (isradipine) in treatment of hypertension in pregnancy: a randomized placebo-controlled study.

OBJECTIVE: Our purpose was to study the effects of isradipine, a dihydropyridine calcium channel blocker, on mother and fetus in the treatment of hypertensive disorders of pregnancy. STUDY DESIGN: The investigation was performed as a two-group, parallel, double-blind multicenter study of isradipine versus placebo. Fifty-four women were randomized to treatment with isradipine slow-release capsules given orally 5 mg twice a day and 57 to a placebo group. RESULTS: Isradipine lowered the maternal mean arterial blood pressure effectively in women with nonproteinuric hypertension but did not do so in women with proteinuria at recruitment or appearing during treatment. Blood flow in the umbilical artery and maternal renal and liver function were not influenced by treatment. Isradipine had few side effects and was well tolerated. CONCLUSION: Calcium channel blockade with isradipine is effective for treatment of nonproteinuric hypertension but not in preeclampsia.

Antihypertensive Agents↗
PubMed1994

Postoperative cerebral oedema after transcervical endometrial resection and uterine irrigation with 1.5% glycine.

Absorption of irrigating solution during transcervical resection of endometrium can cause dilutional hyponatraemia, nausea, and cerebral oedema. We studied 6 patients who absorbed more than 1500 mL of 1.5% glycine, and 14 patients who absorbed less. Cerebral oedema was diagnosed by blinded, paired comparison of computed tomography (CT) scans 3-6 hours and 3-6 days after operation. The absorbed volume of irrigating glycine solution was correlated with peroperative decrease in serum sodium. 10 patients who absorbed 500 mL of glycine or more had postoperative nausea, with cerebral oedema suspected in 9. None of the 10 patients who absorbed less than 500 mL had nausea; changes on CT scan suggestive of cerebral odema were found in 1. 8 patients who absorbed 1000 mL or more had a decrease in serum sodium of 10 mmol/L or more, nausea, and cerebral oedema on CT scan. Cerebral oedema may contribute to the development of postoperative nausea in patients undergoing transcervical surgery who absorb more than 500 mL of 1.5% glycine irrigating solution.

Absorption↗
PubMed1994

Phase II clinical trial of didemnin B in previously treated small cell lung cancer.

Didemnin B (NSC 325319), a cyclic depsipeptide isolated from a Carribean sea tunicate, exhibited potent antitumor activity in preclinical studies. After determining the maximum tolerated dose in our previous phase I/II trial, we conducted a phase II study of this drug in patients with previously treated small cell lung cancer; the starting dose was 6.3 mg/m2 intravenously over 30 min every 28 days. The major side effects were in the neuromuscular system and included severe muscle weakness, myopathy and/or myotonia by electromyography, and elevation of creatine phosphokinase and aldolase levels. We also observed modest increases in bilirubin and alkaline phosphatase levels. There were minimal hematologic toxic effects. No response was observed among 15 evaluable patients, leading us to conclude that didemnin B was toxic but inactive in patients with previously treated small cell lung cancer at the stated dose and schedule. A review of the literature revealed no significant antitumor activity in cancers of the colon, breast, ovaries, cervix, or lung (non-small cell) or in renal cell carcinoma. Further clinical trials for didemnin B may not be warranted at the stated dose and schedule.

Adult↗
PubMed1994

The effects of dihydralazine, labetalol and magnesium sulphate on the isolated, perfused human placental cotyledon.

OBJECTIVE: To assess the effects of dihydralazine, labetalol and magnesium sulphate on the vascular tone in the isolated, perfused human placental cotyledon. METHODS: In vitro perfusion of the fetal compartment of isolated, human placental cotyledons. RESULTS: None of the drugs affected basal vascular tone. The thromboxane A2-mimic U46619 and endothelin-1 induced a concentration-dependent increment in perfusion pressure, while 5-hydroxytryptamine induced a variable increase, and norepinephrine induced a small, transient increase in perfusion pressure. After preconstriction with U46619, magnesium sulphate (1.5 x 10(-3) to 6 x 10(-3) mol/l) induced a decrease in perfusion pressure, while dihydralazine (10(-6) to 10(-4) mol/l) or labetalol (10(-7) to 10(-4) mol/l) enhanced the perfusion pressure. These effects of dihydralazine and labetalol were unaffected by treatment with indomethacin 10(-6) mol/l, but could be reversed by addition of magnesium sulphate 6 x 10(-3) mol/l. Labetalol 10(-6) to 10(-4) mol/l also caused an increase in the perfusion pressure induced by endothelin-1, but showed no effects after preconstriction with 5-hydroxytryptamine. Pretreatment with labetalol 10(-4) mol/l inhibited the transient increase in perfusion pressure induced by norepinephrine 3 x 10(-5) mol/l. CONCLUSIONS: The present data demonstrated that the commonly used vasodilating agents labetalol and dihydralazine do not produce vasodilatation in the human perfused cotyledon after vasoconstriction induced by agents of suggested importance for maintenance of fetal placental vascular tone, and that high concentrations of these drugs may even enhance vasoconstriction induced by thromboxane and endothelin-1 in this area. Magnesium sulphate may show the potential to reverse such unwanted effects of dihydralazine and labetalol.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1994

Effects of transmural field stimulation in isolated muscle strips from rabbit sphincter of Oddi and duodenum.

The purpose of the study was to compare the effect of transmural field stimulation (TMS) on isolated smooth muscle strips from rabbit sphincter of Oddi (SO), duodenal circular layer (Dc) and duodenal longitudinal layer (D1). The strips were suspended in thermostatically controlled 5-ml organ baths containing Krebs solution constantly bubbled with 5% CO2 in O2. TMS was delivered through platinum electrodes (140 V, 0.4 ms, 5 s trains, 40 Hz). The TMS responses could be divided in two main responses: (1) contraction initiated after cessation of the stimulus train, preceded by an inhibitory phase during TMS ('off'); and (2) contraction initiated during TMS ('duration'). The 'duration' response was observed in one out of 20 strips in the SO and Dc compartments, whereas 11 D1 strips (55%) showed 'duration' responses (P < 0.001). Atropine (10(-6)) converted all 'duration' responses to an 'off' response preceded by an inhibitory phase during TMS and reduced the contractile amplitudes with 40-65%. L-NNA significantly increased the number of 'duration' responses in all types of muscle, and caused a 40% increase in D1 contractile amplitude. Inhibitory responses could not be removed by atropine, propranolol and phentolamine. The results suggest that the intrinsic innervation of SO and duodenal muscle consists of a mixture of excitatory, cholinergic and inhibitory NANC pathways. The latter may utilize, wholly or partly, NO or a related compound as transmitter. A relative dominance of excitatory, cholinergic responses was present in the D1 strips, whereas inhibitory responses were dominating in the SO and Dc strips.

Adrenergic Fibers↗
PubMed1993

Endothelin-1: immunocytochemistry, localization of binding sites, and contractile effects in human uteroplacental smooth muscle.

OBJECTIVE: Our purpose was to study the localization, distribution of binding sites, and contractile effects of endothelin-1 in human uteroplacental smooth muscle. STUDY DESIGN: The tissue localization of endothelin-1, the distribution of iodine 125-labeled endothelin-1 binding sites, and the mechanical effects of endothelin-1 were studied in isolated tissues from the human uterus and placenta by immunocytochemistry, autoradiography, and organ bath experiments. RESULTS: No specific endothelin-1 immunoreactivity could be detected in fetal placental tissues or in myometrium or intramyometrial arteries from term pregnant and nonpregnant women. In placental tissues a high density of iodine 125-labeled endothelin-1 binding sites was found in vessels of various sizes and in the chorionic villi, whereas the density in the jelly of Wharton was low. In myometrial tissue from pregnant and nonpregnant women a high density of iodine 125-labeled endothelin-1 binding sites was found, which in myometrium from pregnant women was mainly located to the myometrium and vascular smooth muscle. Endothelin-1 produced marked contractile responses in maternal and fetal uteroplacental vessels and in myometrial preparations. CONCLUSION: Endothelin-1 may be involved in the endogenous control of uteroplacental vascular and visceral smooth muscle.

Arteries↗
PubMed1993

Comparison of the effects of prostanoids on human penile circumflex veins and corpus cavernosum tissue.

The mechanical effects of the prostaglandins PGE1, PGE2, PGF2 alpha and PGI2 were investigated in human isolated penile circumflex veins (CV) and corpus cavernosum (CC) tissue. PGE1 did not affect resting tension, while the compound produced relaxation of both CC and CV preparations after precontraction with noradrenaline (NA) 3 x 10(-6)M. PGE2 produced contraction in CC and CV preparations. After precontraction with NA, however, relaxation was induced in both tissues. PGF2 alpha induced contraction in CC and CV preparations, while no relaxant responses were seen in preparations precontracted with NA. PGI2 produced no mechanical effects in unstimulated CV preparations, whereas dose-related contraction was induced in CC tissue strips. After precontraction with NA, PGI2 showed no effect in 2 of 6 CC preparations, while relaxation was seen in 4. In CV preparations precontracted with NA, PGI2 produced relaxation. Local synthesis of prostanoids may influence resting tension and modulate NA-induced responses not only in human penile CC but also in CV smooth muscle.

Adolescent↗
PubMed1993

Role of the L-arginine/nitric oxide pathway in relaxation of isolated human penile cavernous tissue and circumflex veins.

In human penile corpus cavernosum strips, pre-contracted by noradrenaline, electrical stimulation of nerves evoked non-adrenergic, non-cholinergic (NANC) relaxant responses which could be inhibited by tetrodotoxin 10(-6) M, NG-nitro-L-arginine (L-NNA) 10(-7)-10(-4) M, and oxyhaemoglobin 10(-5) M, but not by methylene blue (MB) 10(-5) M. Acetylcholine-induced relaxations were also inhibited by L-NNA 10(-4) M and oxyhaemoglobin 10(-5) M, but were unaffected by pyrogallol 10(-4) M, MB 10(-5) M, and tetrodotoxin 10(-6) M. MB 5 x 10(-4)-10(-4) M significantly reduced the responses to both electrical stimulation and to acetylcholine. Nitric oxide (NO) 10(-7)-10(-4) M and sodium nitroprusside 10(-9)-10(-4) M caused concentration-dependent relaxations. The NO-induced relaxations were inhibited by oxyhaemoglobin 10(-5) M, and the concentration-response curve for sodium nitroprusside was shifted to the right by MB 10(-5) M. The response to sodium nitroprusside was unaffected by L-NNA 10(-4) M, oxyhaemoglobin 10(-5) M, and pyrogallol 10(-4) M. In circumflex veins, pre-contracted by noradrenaline, no NANC-mediated relaxation was found in response to electrical stimulation; acetylcholine caused endothelium-dependent relaxations, which were insensitive to L-NNA 10(-4) M and oxyhaemoglobin 10(-5) M. NO and sodium nitroprusside caused concentration-dependent relaxations; the concentration-response curves for NO and sodium nitroprusside were shifted to the right by oxyhaemoglobin 10(-5) M. Removal of the endothelium left the NO- and sodium nitroprusside-induced relaxations unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

The role of the L-arginine/nitric oxide pathway for relaxation of the human lower oesophageal sphincter.

Smooth muscle specimens were taken from the oesophagogastric junction (OGJ) in patients operated on for gastrointestinal malignancies not involving the OGJ. The smooth muscle bundles of the inner, circular layer of the OGJ were richly innervated by fine nerve fibres staining positively for NADPH diaphorase. The outer longitudinal layer had a markedly lower number of NADPH-diaphorase positive nerve fibres. When the preparations were suspended in organ baths for recording of isometric tension, they developed active tension. Transmural field stimulation (TMS) induced frequency-dependent relaxations, which were abolished by NG-nitro-L-arginine (L-NNA; 10(-4) M), and were often converted to atropine-sensitive contractions. The effect of L-NNA was concentration-dependent, and the concentration-response curve for L-NNA was shifted to the right by L-arginine pre-incubation. The enantiomer NG-nitro-D-arginine (10(-4) M) also showed inhibitory actions on the responses to TMS, but significantly less than L-NNA. Relaxant responses to vasoactive intestinal polypeptide (VIP), forskolin, and sodium nitroprusside were unaffected by L-NNA pre-incubation. Exposure to a 124 mM K+ solution resulted in a biphasic relaxation of the preparations. This relaxation was not seen in preparations treated with scorpion venom (20 micrograms ml-1) or L-NNA (10(-4) M). Instead, a contractile response to 124 mM K+ solution was found. The results suggest that NANC responses to electrical stimulation of nerves in the human OGJ are mediated by a product generated from L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)

Arginine↗