Mechanism of bradykinin-induced cyclic GMP accumulation in bovine tracheal smooth muscle

Bradykinin (10^–8-10^–5M) caused a concentration-dependent increase in cyclic GMP (cGMP) production in bovine tracheal smooth muscle in the absence of epithelium. The effect was calcium-dependent and was inhibited by pyrogallol (10 M) and methylene blue (10 M). The inhibition of pyrogallol was reversed by superoxide dismutase (100 Usnowml). Nitric oxide (NO) synthase inhibitors, N ^G-methyl-l-arginine (10–100 M) and N ^G-nitro-l-arginine (10–100 M) reduced cGMP accumulation induced by bradykinin in a concentration-dependent fashion, and the inhibition was reversed by l-arginine. Immunohistochemistry with a specific antibody against neuronal NO synthase from rat cerebellum showed positive staining localized in some nerve fibers. Bradykinin-induced cGMP accumulation appears to be related to the release of NO, part of which is probably synthesized in nonadrenergic noncholinergic nerve in bovine trachea.Offprint requests to: Dr. Hong Sheng     

Insulin secretion in rats with chronic nitric oxide synthase blockade

Summary Nitric oxide, which is produced from l-arginine by a nitric oxide-synthase enzyme, has been shown to be a ubiquitous messenger molecule. Recently, it has been suggested that nitric oxide might influence insulin secretion by activating the soluble guanylate cyclase and generating cyclic guanosine monophosphate (cGMP). We have investigated the role of the nitric oxide pathway in insulin secretion by evaluating the insulin response to several secretagogues in rats in which nitric oxide-synthase was chronically inhibited by oral administration of the l-arginine analogue, N^G-nitro-l-arginine methyl ester (l-NAME). Blood pressure and aortic wall cGMP content were used as indices of nitric oxide-synthase blockade. Insulin secretion was evaluated after an intravenous bolus of d-glucose, l-arginine or d-arginine. Chronic l-NAME administration induced a 30% increase in blood pressure and a seven-fold drop in arterial cGMP content. Body weight, fasting plasma glucose and insulin were not influenced by l-NAME administration. First-phase insulin secretion (1+3 min) in response to glucose was not significantly different in l-NAME and control rats. The areas under the insulin curve were similar in both groups. Insulin secretion in response to d-arginine or l-arginine in l-NAME-treated and control rats were also similar. In conclusion, chronic nitric oxide-synthase blockade increases blood pressure and decreases aortic cGMP content, but does not alter insulin secretion in response to several secretagogues. Chronic oral administration of l-NAME in the rat provides an adequate animal model for studying the l-arginine nitric oxide-pathway.Abbreviations NO Nitric oxide - cGMP guanosine 3: 5 cyclic monophosphate - l-NMMA N^G-monomethyl-l-arginine - l-NAME N^G-nitro-l-arginine-methyl-ester - NOD mice non obese diabetic mice     

Nitric oxide-mediated neurotransmission is attenuated in the anococcygeus muscle from diabetic rats

Summary The effect of STZ-induced diabetes of 8-weeks duration was examined on nitric oxide-mediated neurotransmission in the rat anococcygeus muscle. In the presence of noradrenergic blockade and raised tissue tone, relaxant responses to nerve stimulation (0.5–5 Hz, for 10 s), sodium nitroprusside (5 and 10 nmol/l) and nitric oxide (1 and 3 mol/l) were significantly reduced in anococcygeus muscles from diabetic rats compared to responses from control rats (p <0.05). In contrast, relaxations to papaverine (3 and 10 mol/l were not reduced in tissues from diabetic rats. The nitric oxide synthesis inhibitor NOLA (100 mol/l) abolished relaxant responses to nerve stimulation but had no effect on responses to any of the relaxant agents used. Exposure to NOLA at 10 mol/l reduced stimulation-induced relaxations; this reduction was significantly greater in tissues from the diabetic group than from the control group (p <0.05), probably as a consequence of the smaller relaxant responses in muscles from diabetic rats. Contractile responses to nerve stimulation (1–10 Hz, for 10 s), but not noradrenaline (0.03–30 mol/l), were significantly greater in anococcygeus muscles from diabetic rats than from control rats (p <0.05). NOLA (100 mol/l) significantly enhanced stimulation-induced contractions (p <0.05), however the enhancement was significantly less in tissues from diabetic rats (p <0.05). The results suggest that STZ-induced diabetes impairs smooth muscle reactivity to nitric oxide in the rat anococcygeus muscle.Abbreviations STZ Streptozotocin - NOLA N^G-nitro-l-arginine - NANC nonadrenergic noncholinergic - ANOVA analysis of variance     

The role of nitric oxide (NO) in the human internal anal sphincter

Purpose. Nitric oxide (NO) has recently been shown to be a neurotransmitter in nonadrenergic noncholinergic (NANC) inhibitory nerves in the human gut. To clarify the physiological significance of NO in the human internal anal sphincter (IAS), we investigated enteric nervous responses in normal IAS muscle strips above the dentate line, obtained from patients with rectal cancer. Methods. Normal IAS muscle strips above the dentate line, obtained from ten patients who underwent rectal amputation for low rectal cancers were used. The subjects consisted of eight men and two women, aged from 46–72 years (mean age, 54.2 years). A mechanographic technique was used to evaluate in-vitro IAS muscle responses to electrical field stimulation (EFS) of adrenergic and cholinergic nerves before and after treatment with various autonomic nerve blockers, N^G-nitro-l-arginine (l-NNA) and l-arginine. Results. Excitatory nerves were mainly involved in the regulation of enteric nerve responses to EFS in the baseline condition of the study, and NANC inhibitory nerves acted on the normal IAS. l-NNA concentration-dependently inhibited the relaxation in response to EFS in the human IAS, and this inhibitory effect in the IAS was reversed by l-arginine. Conclusions. These findings suggest that NANC inhibitory nerves play important roles in regulating relaxation of the human IAS, and that NO plays an important role as a neurotransmitter in NANC inhibitory nerves of the human IAS. Received: September 7, 2000 / Accepted: January 12, 2001     

Interactions between essential fatty acid,prostanoid, polyol pathway and nitric oxide mechanisms in the neurovascular deficit of diabetic rats

Summary Impaired -6 essential fatty acid metabolism and exaggerated polyol pathway flux contribute to the neurovascular abnormalities in streptozotocin-diabetic rats. The potential interactions between these mechanisms were examined by comparing the effects of threshold doses of aldose reductase inhibitors and evening primrose oil, alone and in combination, on neurovascular deficits. In addition, highdose aldose reductase inhibitor and evening primrose oil treatment effects were challenged by co-treatment with the cyclo-oxygenase inhibitor, flurbiprofen, or the nitric oxide synthase inhibitor, N^G-nitro-l-arginine. Eight weeks of diabetes caused an 18.9% reduction in sciatic motor conduction velocity (p<0.001). This was only modestly ameliorated by a 0.1% dietary supplement of evening primrose oil or the aldose reductase inhibitors ZD5522 (0.25 mg · kg^–1 · day^–1) and WAY121509 (0.2 mg · kg^–1· day^–1) for the final 2 weeks. However, joint treatment with primrose oil and ZD5522 or WAY121509 caused marked 71.5 and 82.4% corrections, respectively, of the conduction deficit. Sciatic nutritive blood flow was 43.1% reduced by diabetes (p<0.001) and this was corrected by 67.8% with joint ZD5522 and primrose oil treatment (p<0.001). High-dose WAY121509 (10 mg · kg^–1 · day^–1) and primrose oil (10% dietary supplement) prevented sciatic conduction velocity and nutritive blood flow deficits in 1-month diabetic rats (p<0.001). However, these effects were abolished by flurbiprofen (5 mg · kg^–1 · day^–1) and N^G-nitro-l-arginine (10 mg · kg^–1 · day^–1) co-treatment (p<0.001). Thus, the data provide evidence for synergistic interactions between polyol pathway/nitric oxide and essential fatty acid/cyclo-oxygenase systems in the control of neurovascular function in diabetic rats, from which a potential therapeutic advantage could be derived.Abbreviations ARI Aldose reductase inhibitor - EPO evening primrose oil - NCV nerve conduction velocity - NO nitric oxide - NOLA N^G-nitro-l-arginine     

A polyamine-glyceraldehyde derivative with anti-tumour activity

Summary A product derived from dl-glyceraldehyde and a synthetic polyamine N,N-bis(-aminopropyl) diaminoethane markedly inhibited the growth of Rd/3 sarcoma in rats.

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Zusammenfassung Eine Derivatsubstanz des dl-Glyeerinaldehyd und eines synthetischen Polyamin N,N-bis-(-aminopropyl)diaminoethan übt eine ausgeprägte Hemmung auf das Wachstum des Rd/3 Sarkomas in Ratten aus.

     

Vasoconstriction induced by ouabain in the canine coronary artery: Contribution of adrenergic and nonadrenergic responses

Summary Ouabain, when applied to rings of the left ciroumfiex coronary artery of the dog (which contains both alpha₁-adrenoceptors leading to contraction and beta₁-adrenoceptors leading to relaxation) caused an initial contraction which peaked within 15 minutes and a later secondary increase in tension which peaked within 60 minutes. These contractions were prevented by Ca²⁺ removal or by verapamil. Adrenergic denervation with 6-hydroxydopamine did not affect the initial contraction. Thus it is due to a nonadrenergic effect of the glycoside. Since the secondary increase in tension was prevented by adrenergic denervation and prazosin, it is likely to be due to norepinephrine released from adrenergic nerves acting on alpha-adrenoceptors. This interpretation was confirmed by the finding that ouabain, after a latent period of about 35 minutes, augmented the output of ³H-norepinephrine from helical strips of the artery previously incubated with tritiated transmitter. In rings contracted with prostaglandin F₂, ouabain reduced beta-adrenergic relaxations caused by isoproterenol or exogenous norepinephrine, but not those caused by sodium nitroprusside. Thus, in this artery, ouabain depresses the response of the beta-adrenoceptors to the norepinephrine which it releases, thereby permitting the neurotransmitter to cause contraction by activating postjunctional alpha₁-adrenoceptors.     

Comparison of effects of upright versus supine body position and liquid versus solid bolus on esophageal pressures in normal humans

New studies monitoring ambulatory esophageal pressures during food ingestion often compare results to normal values obtained from supine liquid swallows. We compared distal esophageal peristaltic and lower esophageal sphincter (LES) pressures in 15 normal subjects during six liquid swallows in the upright and supine positions, and six solid (small marshmallow) swallows in upright position. LES pressures were significantly ( P <0.05) higher supine than upright but no differences were noted in LES pressure, relaxation, and duration of relaxation between upright solid and liquid swallows. Distal peristaltic wave velocities were faster upright than supine. Peristaltic wave amplitudes, durations, and DP/DT were significantly (P <0.05) greater in supine than in upright position. Atypical wave forms, defined as nontransmitted, simultaneous, and simultaneous/repetitive, increased in the upright position compared to supine (P <0.01), and during solid vs liquid swallows (P <0.05). These results indicate that body position substantially affects normal distal esophageal peristalsis and LES pressure and that abnormal wave forms occur more frequently during swallowing solids than liquids in the upright position. Conclusions regarding abnormal motility over prolonged periods and during food ingestion in patients should be tempered by these findings.This was a junior medical student research project of Victor W. Sears, Jr. Presented at the annual meeting of the American College of Gastroenterology, New Orleans, Louisiana, October 1989.     

The hypertensive lower esophageal sphincter

Controversy exists as to whether the hypertensive lower esophageal sphincter (HLES) represents a clinical motility disorder of the esophagus or is merely the right-sided expression of a normal distribution curve. In the present study we describe 16 patients with HLES, defined as a lower esophageal sphincter (LES) pressure of 40 mm Hg (mean +3sd of controls) with normal peristalsis. All of the patients suffered from chest pain and nine from dysphagia. Delayed bolus transit at the gastroesophageal junction was demonstrated in four patients by radiography. Manometric studies showed that during swallowing the LES residual pressures were significantly greater (9.2±5.0 mm Hg) than observed in normal controls (1.8±2.2 mmHg) (mean±1sd). However, the percent LES relaxation in patients did not differ significantly from controls. Clinical improvement was associated with pharmacological or mechanical reduction of resting LES pressure with an accompanying fall in the nadir pressure. These observations suggest that HLES may have clinical and pathophysiological significance and that evidence for the entity should be sought during manometric studies in the clinical laboratory.     

Lipophilic 1-β-d-arabinofuranosyl cytosine derivatives in liposomal formulations for oral and parenteral antileukemic therapy in the murine L1210 leukemia model

TheN ⁴-alkylcytosine arabinoside derivativeN ⁴-octadecyl-AraC (AraC-Ocd, NOAC) and the (1-octadecylglycero-3-phospho)-AraC (Ocd-GroP-AraC, OPA) conjugate are new lipophilic derivatives of the cytostatic drug 1--d-arabinofuranosylcytosine (AraC) that produce high antileukemic effects in the L1210 murine leukemia model when administered orally or parenterally as liposomal formulations. Between 83% and 100% of the treated animals were cured after five consecutive daily oral drug applications with a total dose of 1 mmol/kg AraC-Ocd or Ocd-GroP-AraC. Corresponding results were obtained after parenteral therapy on days 2 and 6 after tumor inoculation with five- to ten-fold lower concentrations of these two compounds. A comparable cytotoxic activity was found with the orally active AraC-5-(n-stearyl phosphate). However, because of its strong hemolytic toxicity this derivative cannot be used for parenteral therapy. Another AraC conjugate, which was modified with two long-chain hydrocarbons, the (1-octadecylglycero-3-phospho)-N ⁴-hexadecyl-AraC was, probably because of poor oral bioavailability, only active when applied parenterally. The new lipophilic AraC derivatives AraC-Ocd and Ocd-GroP-AraC are compounds with a high potential for the oral treatment of leukemias and possibly also of solid tumors.Abbreviations AraC 1--d-arabinofuranosylcytosine - AraC-Ocd N ⁴-octadecyl-1--d-arabinofuranosylcytosine - Ocd-GroP-AraC 5-O-(1-octadecyl-rac-glycero-3-phospho)-1--d-arabinofuranosylcytosine - OcdP-AraC 1--d-arabinofuranosylcytosine-5-(n-stearylphosphate) - Ocd-GroP-AraC-Hxd 5-O-(1-octadecyl-rac-glycero-3-phospho)-N ⁴-hexadecyl-1--d-arabinofuranosylcytosine     

The influence of endurance training on mechanical catecholamine responsiveness, β-adrenoceptor density and myosin isoenzyme pattern of rat ventricular myocardium

Summary An investigation was carried out on the effects of 4 weeks' swimming training (2×90 min/day) on myocardial isometric tension development and rate of tension rise, and also on the changes induced therein by in vitro application of isoproterenol. This was done in 9 isolated papillary muscles of 9-weekold male Wistar rats and the results were compared with the data of age-matched sedentary controls. Ventricular -adrenoceptors ([³H]-dihydroalprenolol binding) and the isoenzyme pattern of myosin (pyrophosphate gel electrophoresis) were examined in the same individuals. Isometric tension (T) and its first derivative (dT/dt) measured at the optimum of the length-tension diagram were moderately increased by long-term swimming training. Isoproterenol (10^–5 mol/l) induced a greater absolute and relative increase of both mechanical parameters in specimens of trained animals than in age-matched controls (T: 3.6±1.6 vs. 1.9±0.6×10^–2 N/mm², p<0.05. dT/dt: 43.4±14.0 vs. 30.4±9.5×10^–2 N/mm²·s, p<0.05). K _d decreased significantly (4.23±1.0 vs. 2.44±0.3 nM, p<0.02), indicating an increase in receptor affinity, whereas receptor density revealed a tendency to decrease (98.8±22.6 vs. 67.1±18.0 fmol/mg protein, p<0.1). In addition, there was a shift in the isoenzyme pattern of myosin towards VM-1 after swimming training.Thus, under the conditions of the present experiments, the mechanical response to isoproterenol does not correlate to -adrenoceptor density. It is probable that, apart from the altered sensitivity of the receptors, other membrane or post-membrane processes, are responsible for the increased mechanical responsiveness to catecholamines. Although a relationship between myosin isoenzyme pattern and mechanical responsiveness to catecholamines is apparent taking into account our results and the findings on hypertensive rats as reported in the literature, it cannot be accounted for simply by altered -adrenoceptor density.     

Nitric oxide in ischaemic acute renal failure of streptozotocin diabetic rats

Summary Changes in nitric oxide (NO) levels were determined in ischaemic acute renal failure in streptozotocin-induced diabetes mellitus rats. Two weeks after streptozotocin administration and immediately after right nephrectomy, the left renal artery was occluded for 60 min. Similar procedures were carried out in non-diabetic rats. The nitrite (NO₂) + nitrate (NO₃) levels were measured in plasma and urine. The effects of chronic oral supplementation with l-arginine and an NO synthase inhibitor (N-omega-nitro-l-arginine) were also studied in both diabetic and non-diabetic rats before and after renal artery clamping. The rats with diabetic acute renal failure had a much lower creatinine clearance (90±22 l · min^–1 · 100 g body weight^–1, p<0.005), and higher fractional excretion of sodium (FENa)% (10.90±4.2, p<0.001) and protein excretion (2078±69 g/ml creatinine clearance, p<0.001) compared with the respective values in the non-diabetic groups (163±30; 1.46±86; 453.3±31). The plasma and urine NO₂ + NO₃ levels were significantly higher in the untreated diabetic rats compared with the untreated normal rats before ischaemia (p<0.001). The ischaemic acute renal failure in non-diabetic rats increased the plasma and urinary NO₂ + NO₃ excretion after ischaemia. The urinary excretion of these metabolites decreased significantly and their plasma levels remained unchanged in the ischaemic diabetic rats. The l-arginine administration resulted in a small but significantly higher creatinine clearance after clamping in the non-diabetic rats. The NO synthase inhibitor caused deterioration in renal function in all ischaemic and non-ischaemic groups. In summary, the greater vulnerability to ischaemia of the diabetic kidney seems to be associated with both impaired response to and impaired production of NO.Abbreviations IARF Ischaemic acute renal failure - STZ streptozotocin - NOSi nitric oxide synthase inhibitor - ARF acute renal failure - Ccr creatinine clearance - FENa% fractional excretion of sodium     

Cholinergic Stimulation and Nonadrenergic, Noncholinergic Relaxation of Human Colonic Circular Muscle in Idiopathic Chronic Constipation

The aim of our study was to further investigatethe pathophysiological mechanism underlying idiopathicchronic constipation (ICC), a disorder of colonicmotility. A possible alteration of excitatory and inhibitory neurotransmission and also the roleof inhibitory neurotransmitters such as nitric oxide(NO), 5-adenosine triphosphate (ATP), andvasoactive intestinal peptide (VIP) has been evaluatedon preparations of distal colon from patients with or withoutICC. The isometric tension was recorded from isolatedcircular muscle strips of both experimental groupsduring pharmacological and electrical field stimulation (EFS). The contractile response obtained byacetylcholine (ACh 20 M), EFS (20 Hz, 20 V, 1 msec,pulse trains lasting 1 min) and substance P (SP 1 M)was significantly lower in ICC than in controlpreparations. The effect of inhibitory nonadrenergic,noncholinergic innervation was evaluated using EFS atlow frequencies (0.5-8 Hz), after cholinergic andsympathetic blockade with atropine (3 M) andguanethidine (3 M). The maximum relaxation valueexpressed as percentage of inhibition of SP-inducedcontraction was significantly higher in ICC than incontrol preparations (87 ± 2.4 and 67 ±6.3, respectively; P < 0.05). Experiments with substances thatantagonize or reduce the effect of putative inhibitorymediators (VIP 6-28, apamin andN^G-nitro-L-arginine) suggest that analteration in NO and ATP release is present in ICC preparations. In particularat a higher inhibitory frequency NO-mediated relaxationis enhanced in ICC vs control, supporting the hypothesisthat excessive NO production may be involved in pathophysiological mechanism ofconstipation.     

Role of Diaphragmatic Crura and Lower Esophageal Sphincter in Gastroesophageal Reflux Disease: Manometric and pH-Metric Study of Small Hiatal Hernia

The rapid pull-through (RPT) technique during esophageal manometry helps to identify various pressure profiles of hiatal hernia (HH), based on the presence of two high pressure zones: the diaphragmatic crura (DC) and the lower esophageal sphincter (LES). Our aim was to correlate different HH profiles with frequency of reflux episodes in patients with gastroesophageal reflux disease (GERD). Seventy-eight patients with GERD and HH underwent esophageal manometry with RPT and were grouped according to the prevalent pressure profile of HH. Twenty-four-hour pH-metry served to quantify traditional (TR) and nontraditional refluxes (drop of 1 pH unit with pH > 4 or pH < 4 and time < 5 sec) (NTR) during total, upright, and recumbent periods. The group with a prevalent flat HH profile, representing LES and DC impairment, had significantly more TRs in total time of reflux (P < 0.01) and in recumbent and upright periods (P < 0.05) compared to the group with a prevalence of the two pressure peaks, corresponding to LES and DC efficiency. However, the group with the flat profile had significantly more NTRs + TRs than the group with pressure peaks in total time (P < 0.01) and recumbent position (P < 0.001) but not in the upright position. Hiatal hernia predisposes to GERD, but only the associated impairment of the LES and diaphragmatic crura pressures represents a condition of high risk for gastroesophageal reflux events.     

The Role of Nitric Oxide in Ethanol-Induced Gastrointestinal Dysfunction

We recently showed that acute ethanol inhibits contractility of the lower esophageal sphincter (LES) and the lower esophageal body (LEB) both in vivo and in vitro. To evaluate the mechanism of this inhibitory effect of ethanol, we investigated the role of nitric oxide (NO) on contractility of isolated LES and LEB circular muscle strips using inhibitors of NO synthase (NOS), N ^G-itro- l -arginine methyl ester and N ^G-nitro- l -arginine. Ethanol significantly decreased LES basal tone. This effect was not mediated by NO, because inhibition was not prevented by inhibitors of NOS. Electrical field stimulation caused an On-response relaxation from LES strips, and an Off-response contraction from both LES and LEB strips. Inhibitors of NOS prevented the On-response relaxation of LES, but had no significant effect on LES Off-response contraction. Ethanol potentiated the On-response relaxation of the LES Off-response contraction. Ethanol potentiated the On-response relaxation of LES, but had no significant effect on Off-response contraction. Ethanol's potentiating effect of the On-response relaxation is NO-mediated, because it was abolished by NOS inhibitors. Ethanol also inhibited carbachol-induced LES contractility. This inhibitory effect was NO-mediated, because NOS inhibitors abolished it. Ethanol inhibited both the Off-response contraction and carbachol-induced contraction of LEB strips. These effects were not NO-mediated, because they were not affected by NOS inhibitor. These data suggest that NO is not a mediator for the inhibitory effect of ethanol on LEB contractility, and that NO seems to be a mediator of ethanol inhibition of some aspects of LES motor functions.     

Nerve-mediated nitric oxide production by opossum lower esophageal sphincter

Antagonists of nitric oxide synthesis inhibit nerve-induced hyperpolarization and relaxation of muscle from the opossum lower esophageal sphincter. These studies test the hypothesis that nitric oxide is released during stimulation of intrinsic esophageal nerves. The intrinsic nerves were stimulated with an electrical field (10-sec trains of 1-msec, 30-V pulses delivered at 10 Hz). Nitric oxide production was measured with a DASIBI model 2108 Chemiluminescence NO Analyzer.N ^G-Nitro-l-arginine, an inhibitor of NO synthase, antagonized nerve-induced relaxation the lower esophageal sphincter. Nerve stimulation increased NO production from 0.50±0.04 nmol/min/100 mg tissue to 0.87±0.07 nmol/min/100 mg tissue (P<0.01).N ^G-nitro-l-arginine inhibited both basal (0.030±0.09 nmol/min/100 mg tissue,P<0.05 vs baseline) and stimulated (0.38±0.10 nmol/min/100 mg tissue,P<0.01 vs stimulated). These studies support the hypothesis that nerve stimulation releases nitric oxide from the lower esophageal sphincter.     

Role of nitric oxide in relaxation of the longitudinal layer of rectal smooth muscle

PURPOSE: This study was designed to investigate the role of nitric oxide in neurogenic relaxation of the longitudinal layer of human rectal smooth muscle. METHODS: Tissue was obtained from the mid rectum of patients undergoing anterior resection for carcinoma. Adjacent strips of longitudinal muscle were dissected and mounted in organ baths for isometric tension recording. In preliminary experiments to determine the response of strips to cholinergic, adrenergic, and potential excitatory agonists, strips were superfused with standard Krebs solution (37±0.5°C; pH, 7.4±0.05). Investigation of inhibitory, nonadrenergic noncholinergic responses required the addition of 3×10⁻⁶ M histamine to induce reproducible and stable tension for five-minute “test” periods, during which electrical field stimulation (EFS) and additional drugs were applied. In these experiments, strips were superfused with Krebs solution that contained atropine sulfate (3×10⁻⁶ M) and guanethidine (3×10⁻⁶ M). RESULTS: The response to cholinergic and adrenergic agonists was typical of nonsphincter specialized gastrointestinal smooth muscle. EFS elicited frequency-dependent, neurogenic (tetrodotoxin-sensitive) relaxations of precontracted strips, which were reduced in dose-dependent fashion by addition ofNω-nitro-l-arginine and restored by addition of 3×10 ⁻⁴ M l-arginine but not by d-arginine. Addition of exogenous nitric oxide (sodium nitroprusside) mimicked the relaxant response induced by EFS. CONCLUSION: Smooth muscle from the longitudinal layer of human rectum receives an intrinsic inhibitory innervation mediated by nitric oxide. Supported and financed by the Medical Research Council, United Kingdom. John Stebbing is in receipt of a Medical Research Council Clinical Training Fellowship. Read at the meeting of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 9 to 14, 1996.     

Manometric assessment of esophageal motility in patients with primary Sjögren’s syndrome

Objective The aim of this study was to assess the esophageal motility by manometry in patients with primary Sjögrens syndrome.Methods Esophageal manometry was carried out in 40 patients with primary Sjögrens syndrome (SS), 15 with rheumatoid arthritis (RA), 15 with RA and secondary SS, and 21 healthy volunteers.Results We found that the mean lower esophageal sphincter (LES) pressures measured by station pull-through and rapid pull-through techniques were significantly higher in primary SS patients than with healthy controls and RA patients with or without SS (P<0.05). Our study did not show any major differences when comparing the three patient groups (P>0.05). However, peristaltic contraction velocity was lower and peristaltic contraction duration significantly higher at the middle and lower thirds of the esophagus in primary SS patients than in healthy controls (P<0.05).Conclusion The results of our study support the view that various esophageal motility disorders can be found in patients with primary SS which could be related to an increase in LES pressure. We also found no correlation of the esophageal abnormalities with other factors studied, suggesting that the cause of dysphagia is multifactorial in nature.     

Pharmacological manipulation of vascular endothelium function in non-diabetic and streptozotocin-diabetic rats: effects on nerve conduction,hypoxic resistance and endoneurial capillarization

Summary We examined the potential for some of the abnormalities of vascular endothelium found in diabetes mellitus to cause neuropathic changes. Non-diabetic rats were treated for 2 months with the cyclo-oxygenase inhibitor flurbiprofen (5 mg·kg⁻¹·day⁻¹) to reduce prostacyclin production, the nitric oxide synthase inhibitor N^G-nitro-L-arginine (5 or 25 mg·kg⁻¹·day⁻¹), or combined treatment. There were dose-dependent reductions in sciatic motor and saphenous sensory conduction velocity. The two inhibitors acted synergistically, thus, the 5–6% motor conduction deficits (p<0.01) produced by either flurbiprofen or N^G-nitro-l-arginine (5 mg·kg⁻¹·day⁻¹) increased to 17% (p<0.001) for combined treatment. With N^G-nitro-l-arginine (25 mg·kg⁻¹·day⁻¹) and flurbiprofen, motor and sensory conduction velocity were reduced by 23% (p<0.001) and 12% (p<0.001), respectively, matching the deficits following 2-month streptozotocin diabetes. N^G-nitro-l-arginine (25 mg·kg⁻¹·day⁻¹) and flurbiprofen together produced a 13% prolongation of the time taken for 80% hypoxic conduction failure in vitro (p<0.05) and a 10% reduction in sciatic capillary density. A second investigation tested an alternative hypothesis that overproduction of nitric oxide was responsible for vascular-related complications in diabetes, the prediction being that N^G-nitro-L-arginine (5 mg·kg⁻¹·day⁻¹) would prevent nerve dysfunction. However, rather than prophylaxis during 2-month streptozotocin diabetes, treatment exacerbated nerve abnormalities. Thus, N^G-nitro-L-arginine worsened (8%,p<0.001) the motor conduction deficit, there was an 11% increase in hypoxic conduction failure time (p<0.01) and an 11% reduction in endoneurial capillary density (p<0.01). We conclude that overproduction of nitric oxide is unlikely to be involved in the aetiology of experimental diabetic neuropathy. However, endothelial dysfunction resulting in impaired nitric oxide and prostacyclin synthesis could make a substantial contribution.     

Oestradiolund Progesteron-bindende Receptoren sowie 17β-Hydroxysteroiddehydrogenase in Endometriumcarcinomen der Frau vor und nach Gestagen-Behandlung

Zusammenfassung Gegenstand der vorliegenden Untersuchung war die Bestimmung der spezifischen Aktivität der cytoplasmatischen, mikrosomalen, mitochondrialen und nuclearen 17-Hydroxysteroid Dehydrogenase (17-HSD) sowie der Konzentration der spezifischen cytoplasmatischen Oestradiol und Progesteron-bindenden Receptorproteine im Endometriumgewebe des Menschen. Die im normalen Gewebe erhaltenen Werte wurden korreliert mit dem Cyclusstadium, die der Endometriumcarcinome in Beziehung zum Differenzierungsgrad des Tumorgewebes gesetzt. Außerdem wurde der Einfluß der Gestagen-Therapie auf die 17-HSD-Aktivität und den endogenen Steroidhormon-Receptorgehalt geprüft.Es zeigte sich, daß in allen subcellulären Fraktionen die 17-HSD-Aktivität in der Sekretionsphase um den Faktor 10 höher lag als in der Proliferationsphase. Die endogene Oestradiol-Rezeptorkonzentration war durch hohe Werte in der frühen Proliferationsphase und niedrige während der Sekretionsphase charakterisiert; die Progesteron-Receptorkonzentration verhielt sich dazu gegensinnig.In Endometriumcarcinomen korrelierte die 17-HSD-Aktivität mit dem Differenzierungsgrad des Tumorgewebes: relativ hohe Werte in hochdifferenzierten, dagegen niedrige in undifferenzierten Tumorformen. In bezug auf den endogenen Steroidhormon-Receptorgehalt war das Tumorgewebe durch niedrige Progesteron-bei hohen Oestradiol-Receptorkonzentrationen gekennzeichnet. Auf Gestagengabe reagierten die hochdifferenzierten Tumorformen mit einem deutlichen Anstieg der 17-HSD-Aktivität und einer Zunahme des Progesteron-Receptorgehalts.

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Effect of gestagen therapy upon estradiol- and progesterone-receptor-level and 17-hydroxysteroid dehydrogenase in human endometrial adenocarcinoma

Summary Oestradiol was converted to oestrone about ten times more rapidly by subcellular fractions of normal human endometrium of the secretory phase than by tissue of the proliferative phase. In subcellular fractions of endometrial carcinoma the 17-hydroxysteroid dehydrogenase (17-HSD) activity decreased with decreasing differentiation of the tumour. Most of the 17-HSD activity was located in mitochondrial and microsomal fractions of both normal and neoplastic endometrium. After treatment of patients with gestagens only the well differentiated carcinomata significantly increased in 17-HSD activity demonstrating that the hormonal stimulus leads to similar effects on the 17-HSD activity as in normal endometrium.Furthermore quantitative aspects of the in vitro binding of ³H-oestradiol and ³H-progesterone to receptor components from normal endometrium and endometrial carcinoma cytoplasmic fractions have been studied. In normal tissue the number of cytoplasmic binding sites for both oestradiol and progesterone varied dramatically during the menstrual cycle: number of oestradiol binding sites were highest during the proliferative phase and fell during the secretory phase; for progesterone sites the contrary was the case. In all endometrial carcinomata high oestradiol binding activity was observed. In contrast the number of progesterone sites in the tumours was related to the state of differentiation, which paralled the progestional sensitivity of these tumours.