Effects of intragastric and intravenous glucose on restraint model of stress ulceration

Intragastric glucose prevents acute stress-induced gastric mucosal injury in the restrained rat. Because increased gastric contractions contribute to mucosal injury in this model and because parenteral glucose infusions have been shown to suppress gastric contractility, we hypothesized that centrally mediated responses to hyperglycemia might contribute to the cytoprotective effect of intragastric glucose. We compared intragastric and intravenous 25% glucose with saline infusions during cold restraint and measured their impact on gastric contractility), acidity, and mucin concentration. We found that both intravenous and intragastric glucose infusions increased serum glucose to over 500 mg/dl after 4 hr of stress. Intragastric glucose increased residual volume and gastric pH, as well as decreased gastric mucosal injury, but intravenous glucose had no effects on gastric function. We found that none of the potentially protective effects of intragastric glucose are mediated by central responses to hyperglycemia, and likewise that intravenous glucose has no effect on gastric mucosal injury.Presented in poster format at the 91st Meeting of the American Gastroenterological Association, May 12, 1990, San Antonio, Texas. Supported by Veterans Affairs Medical Research funds and by Dr. Kleiman-Wexler's BSG NIH.     

Effect of sildenafil on gastric emptying and postprandial frequency of antral contractions in healthy humans

Background: Sildenafil is known to block phosphodiesterase type 5, which degrades nitric oxide‐stimulated cyclic guanosine monophosphate, thereby relaxing smooth muscle cells in various organs. The effect of sildenafil on gastric motor function after a meal was investigated in healthy humans. Methods: Ten healthy male volunteers (21–28 years) participated in a placebo‐controlled, double‐blind, cross‐over study. In random order and on two separate days each volunteer ingested either 50?mg sildenafil (Viagra, Pfizer, New York, N.Y., USA) or placebo. A gamma camera technique was used to measure gastric emptying and postprandial frequency of antral contractions. Results: The area under the curve of gastric retention versus time of liquid or solid radiolabelled marker was not changed by sildenafil intake, nor was the postprandial frequency of antral contractions affected by sildenafil. Conclusion: A single dose of 50?mg sildenafil does not change gastric emptying or postprandial frequency of antral contractions in healthy volunteers.     

The ionic mechanism of phenylephrine-induced rhythmic contractions in rabbit mesenteric arteries treated with ryanodine

Phenylephrine induces endothelium-independent rhythmic contractions in ryanodinetreated rabbit mesenteric arteries. To elucidate the ionic mechanism of this rhythmic behaviour, rabbit mesenteric arterial rings were suspended in an organ chamber for isometric tension studies. Yohimbine, propranolol, and atropine had no effect on these contractions, minimizing the possibility that transmitter release from nerve terminals was involved. Additionally, the oscillatory contractions were not altered by diphenhydramine, cimetidine, and indomethacin, thus ruling out the involvement of histamine and prostaglandins. This oscillatory response was completely abolished after the removal of extracellular Ca 2+, as well as after Ca 2+ channel blockade by diltiazem or nifedipine. Sparteine and quinidine, Ca 2+-activated K+ channel antagonists, also abolished the oscillation. In contrast, tetraethylammonium and 3,4-diaminopyridine, voltage-dependent K+ channel antagonists, augmented the response. Glibenclamide, an antagonist of the ATP-sensitive K+ channel, had no effect on the rhythmic contractions. These results suggest that the rhythmic contractions observed in rabbit mesenteric arteries after ryanodine treatment were caused by the movement of Ca 2+ and K+ across the plasmalemma via the voltage-dependent Ca 2+ channel and the Ca 2+-activated K+ channel, respectively.     

Oesophageal wall stress and muscle hypertrophy in high amplitude oesophageal contractions.

Excessive wall stress is a known stimulus for muscle growth. We recently reported a thickened muscularis propria in patients with high amplitude oesophageal contractions (HAEC). The goal of this study was to determine oesophageal wall stress in normal subjects and patients with HAEC. A manometry catheter equipped with a high frequency ultrasound (US) transducer was used to record pressure and US images simultaneously in 10 healthy subjects and 11 patients with HAEC. Recordings were obtained at 2 and 10 cm above the lower oesophageal sphincter during water swallows. The changes in circumferential wall stress during oesophageal contraction in both groups are relatively small because of an increase in the wall thickness-to-radius ratio during contraction. Patients show a greater muscle thickness than normal subjects at rest and at the peak of contraction. The wall stress in patients is elevated at the 2 cm but not at the 10-cm level as compared to normal subjects. Wall strain is not different between the two groups. Increase in wall thickness during oesophageal contraction maintains low wall stress. A greater wall stress in patients with HAEC may be a stimulus for the increased wall thickness.     

Effects of Cholera Toxin on Small Intestinal Motor Activity in the Fasted State

We sought to determine the effect of cholera toxin on small intestinal motor activity in the fasted state and relate it to secretion in conscious dogs. Motor activity was recorded by strain gauge force transducers and secretion was measured by diverting it to the outside through a two-way cannula. Inoculation of the study segment with cholera toxin resulted in a 10-fold increase in fluid output by 120 minutes postinjection. At the same time that fluid output increased Significantly changes in fasting motor activity occurred. The cycle length of the migrating motor complex was significantly reduced, the percentage of phase II activity was significantly increased, and migrating clustered contractions were inhibited. Perfusion of the study segment by a nonabsorbable electrolyte solution at a rate similar to the rate of secretion induced by cholera toxin did not change the cycle length of migrating motor complexes, but the percentage of phase II activity was significantly increased as with cholera toxin, and migrating clustered contractions were inhibited. The reduction in the cycle length of migrating motor complexes seems to be a direct effect of cholera toxin on the gut wall while the increase in percentage of phase II activity and inhibition of migrating clustered contractions appear to be indirect effects due to fluid accumulation.     

感传路线与皮层体觉诱发电位地形图的比较

为了探讨循经感传与大脑皮层体觉诱发电位地形图的关系，我们采用脑电地形图这一方法，分别对１６名循经感传显著者和无感传者胆经的光明或侠溪穴进行电针刺激。结果表明：感传显著者中有７５％的人在皮层体觉诱发电位地形图的下肢和面部代表区同时出现了二个反应灶，无感传者只有２５％。说明“外周动因激发”是产生循经感传现象的主要因素     

PLASMA FROM NORMAL PREGNANT WOMEN ALTERS THE REACTIVITY OF RABBIT AORTIC SMOOTH MUSCLE WITH FUNCTIONAL ENDOTHELIUM

1. The effects of normal human pregnant plasma on the reactivity of rabbit aortic rings with documented endothelium have been studied. The rings were incubated in plasma from either normal pregnant or non-pregnant women and the effects of incubation on their responses to noradrenaline (NA), calcium chloride stimulation and potassium chloride-induced relaxation were examined. 2. There was no significant difference in the responses to NA in rings incubated in plasma from either pregnant or non-pregnant women. 3. The responses of the rings, incubated in both types of plasma, to calcium chloride stimulation through receptor-operated channels were similar, but rings incubated in plasma from pregnant women demonstrated decreased sensitivity and contractility to calcium chloride stimulation through voltage operated channels. 4. Potassium chloride-induced relaxation was significantly enhanced in rings incubated in plasma from normal pregnant women. The pattern of the responses was unaltered by either de-endothelialization or pretreatment of the rings with indomethacin. 5. The effects of plasma from pregnant women are similar to what has been reported as characteristic of vascular smooth muscle in normal pregnancy.     

Rapid filling cystometry for predicting poor symptomatic results after transurethral prostatic surgery

Twenty-seven patients with symptomatic bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH) were evaluated preoperatively by standard urodynamic investigation and by rapid filling cystometry (RFC). Rapid filling cystometry was performed by injecting a maximum of 120 ml saline into the empty bladder through a catheter at a constant flow rate over 4 seconds. Twenty-three patients were reexamined 3 months after transurethral prostatic surgery. Three patients had not improved symptomatically. None of these three had uninhibited detrusor contractions (UDC) by RFC, but medium filling cystometry revealed UDC in 2 of the patients, both pre- and postoperatively. Rapid filling cystometry, as used in this study, correlated poorly with medium filling cystometry and failed to identify the patients that will not benefit from prostatic surgery due to persistent postoperative UDC.