Superior mesenteric artery is more important than inferior mesenteric artery in maintaining colonic mucosal perfusion and integrity in rats

Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO₂). The patterns of ischemia without congestion (IHB, ISO₂) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO₂) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO₂, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.     

Endoscopic demonstration that vasopressin but not propranolol produces gastric mucosal ischemia in dogs with portal hypertension

Endoscopic reflectance spectrophotometry was used to compare the effect of vasopressin and propranolol on gastric mucosal hemodynamics in dogs with surgically induced esophageal varices and prehepatic portal hypertension. Reflectance spectrophotometry provides indices of mucosal hemoglobin concentration (IHB) and oxygen saturation (ISO2). Hyperemia (increased IHB, normal ISO2), ischemia without congestion (decreased IHB, decreased ISO2), and ischemia with congestion (increased IHB, decreased ISO2) are accompanied by characteristic patterns of IHB and ISO2. Under anesthesia, measurements were obtained on separate days from the gastric corpus mucosa of eight dogs before and 2 to 10 min after either 1 to 5 units of intravenous vasopressin or 1 mg of propranolol. Results revealed that vasopressin (in doses that significantly reduced variceal and portal venous pressure in this animal model) produced a reduction in both IHB and ISO2, indicating gastric mucosal ischemia secondary to splanchnic vasoconstriction. On the other hand, propranolol in a dose that significantly reduced pulse rate by 27 +/- 2% had no effect on IHB or ISO2, suggesting that this dose of propranolol has no direct vasoactive effect on the gastric (splanchnic) circulation.     

Reduction in index of oxygen saturation at margin of active duodenal ulcers may lead to slow healing

This study tested the hypothesis that reduced perfusion of a duodenal ulcer margin (ie, the mucosa 1–2 mm from the edge of the ulcer base) is associated with slow healing. Reflectance spectrophotometric measurement of indices of mucosal hemoglobin concentration (IHB) and mucosal hemoglobin oxygen saturation (ISO₂) were obtained endoscopically in 21 patients at the ulcer margin and the adjacent mucosa (ie, the mucosa 1–2 cm from the edge of the ulcer base). In 17 patients with adequate follow-up, stepwise multilinear regression analysis revealed a significantly negative correlation (r=s-0.69, P < 0.05) between ISO₂ at the ulcer margin minus ISO₂ at the adjacent mucosa (ISO)₂ and ulcer healing time. In addition, smoking, being black, and early relapse since the last ulcer attack were found to be associated with increased duration required for healing. The results of this pilot study suggest factors, in addition to smoking, that may have to be considered in future studies concerned with duodenal ulcer healing.This work was supported by the National Institute of Arthritis and Metabolism and Digestive Diseases Grant AM34840, American Society for Gastrointestinal Endoscopy Career Development Award H850208, Veterans Administration Medical Research Funds, and UCLA Academic Senate Grant 4063.     

Rectal mucosal hemodynamics, evaluated by reflectance spectrophotometry, in patients with chronic hepatitis

To evaluate rectal mucosal hemodynamics in patients with chronic hepatitis, we employed reflectance spectrophotometry and examined the results in relation to the presence and severity of chronic hepatitis. Twenty-six patients with histologically diagnosed chronic hepatitis and 21 controls were examined for rectal vascular findings by endoscopy. Indices (I) of rectal mucosal oxygen saturation (ISO₂) and rectal mucosal hemoglobin (IHb) concentration were measured. To minimize the effects of systemic anemia, the IHb was divided by blood Hb concentration, giving the rectal index for Hb (RHb). The relationship between rectal mucosal hemodynamics and the histological grade of chronic hepatitis was studied. Rectal vascular lesions were observed in three patients with chronic hepatitis (11.5%). The RHb in patients with chronic hepatitis was significantly higher than that in the controls (5.74 ± 0.71 and 4.82 ± 1.12, respectively; P < 0.01). There was no significant difference in ISO₂ levels (44.23 ± 5.84 and 41.94 ± 4.91, respectively). No significant correlation was observed between rectal mucosal hemodynamics and the histological severity of chronic hepatitis, although rectal mucosal hemodynamics changed in patients with chronic hepatitis. Early vascular changes were observed in the rectal mucosa of patients with chronic hepatitis. (Received Oct. 23, 1997; accepted Dec. 19, 1997)     

Colonic mucosal hemodynamics and tissue oxygenation in patients with ulcerative colitis: Investigation by organ reflectance spectrophotometry

Colonic mucosal hemodynamics were investigated at the rectosigmoidal region of the colon in 46 patients with ulcerative colitis and in 18 normal subjects by organ reflectance spectrophotometry under colonoscopy. The value for the index of mucosal hemoglobin concentration (IHb) was significantly higher, and value for the index of mucosal hemoglobin oxygen saturation (ISO₂) was significantly lower in patients with active ulcerative colitis than values in the normal controls or in patients with inactive ulcerative colitis. The results indicate mucosal congestion and hypoxemia in patients with active ulcerative colitis. The changes in IHb and ISO₂ correlated well with the severity of ulcerative colitis scored by endoscopic findings and with the number of infiltrating inflammatory cells in the mucosa analyzed histologically in biopsy samples. In conclusion, the colonic mucosal microcirculation in patients with active ulcerative colitis was disturbed and showed congestion and hypoxemia. The analysis of hemodynamic changes may be helpful for assessing the activity of ulcerative colitis.     

Mechanical pumping of portal blood to the liver: hemodynamic effects of a new experimental treatment for portal hypertension

Background/Aims: It has been suggested that mechanical pumping of portal blood to the liver may correct portal hypertension while increasing portal flow to the liver, which may enhance liver function in cirrhosis. However, the hemodynamic effects of this procedure are unknown. The present study investigated these issues in rats with portal hypertension due to portal vein stenosis.Methods: Mechanical pumping of portal blood to the liver was established by an extracorporeal shunt bypassing the portal vein stenosis, connected to a continuous withdrawal/infusion pump. Portal pressure, portal-systemic shunting (mesenteric injection of Cr-51 microspheres, n=10), mesenteric artery blood flow (perivascular Transonic flowmeter, n=7) and systemic hemodynamics and regional blood flows (left ventricle injection of Ce-141 microspheres, n=15), were measured at pumping rates of 0, 3 and 6 ml·min⁻¹.Results: Mechanical pumping of portal blood to the liver caused a marked decrease in portal pressure (from 17±1 to 12.6±1 and 9.4±.9 mmHg at pumping rates of 0, 3 and 6 ml·min⁻¹) and portal-systemic shunting (from 97±4 to 70±4 and 51±6% respectively) (p<0.001). However, there were no significant changes in mesenteric artery flow (5.5±3 vs 5.6±3 ml·min⁻¹·100 g⁻¹), suggesting that all blood pumped to the liver was withdrawn from that circulating through the collaterals. Moreover, there were no changes in mean arterial pressure, cardiac index, peripheral resistance and splanchnic arteriolar resistance.Conclusions: The short-term mechanical pumping of portal blood to the liver effectively decreases portal pressure and portal-systemic shunting and has no significant effects on systemic and splanchnic hemodynamics in portal hypertensive rats.     

Protective effect of omeprazole on gastric mucosal of cirrhotic portal hypertension rats

Objective:To observe the protective effect of omeprazole on gastric mucosal of cirrhotic portal hypertension rats.Methods:All rats were randomly divided into normal control group,cirrhosis and treatment group.Thioacetamide was used to establish rat model of cirrhotic portal hypertension.The necrotic tissue of gastric mucosa ulcer focus,degree of neutrophils infiltration at the ulcer margin,portal pressure,portal venous flow,abdominal aortic pressure,abdominal aortic blood flow at front end,gastric mucosal blood flow(GMBF),glycoprotein(GP)of gastric mucosa,basal acid secretion,H' back-diffusion,gastric mucosal damage index,NO,prostaglandin E_2(PGE_2) and tumor necrosis factor-α(TNF-α) were determined respectively,and the pathological changes of gastric mucosa were also observed by microscope.Results:Compared with cirrhosis group and the control group,the ulcer bottom necrotic material,gastric neutrophil infiltration and UI of the treatment group were all decreased significantly(P0.01),GMBF value,GP values,serum NO,PGE_2,TNF- a were all significantly increased.Conclusions:Omeprazole has an important protective effect on gastric mucosal and it can increase gastric mucosal blood flow and related to many factors.     

Impaired gastric mucosal energy metabolism in congestive gastropathy in cirrhotic patients

To clarify the characteristics of congestive gastropathy, we investigated gastric mucosal hemodynamics and energy metabolism in cirrhotic patients, using a reflectance spectrophotometry system and high performance liquid chromatography. The index of the gastric mucosal blood volume of cirrhotic patients with esophageal varices was significantly higher, and the index of gastric mucosal blood oxygenation significantly lower, than those in controls, thus indicating congestion and hypoxia in the gastric mucosa. Energy charge levels in the gastric mucosa of cirrhotic patients with esophageal varices were also significantly decreased. The energy charge level showed a strong linear correlation with the index of mucosal blood oxygenation in the antral (r=0.996,P<0.01) and body (r=0.994,P<0.01) mucosa of the stomach. These findings suggest that congestive gastropathy in a portal hypertensive state causes hypoxia in the gastric mucosa, leading to a mucosal energy deficit that may increase mucosal susceptibility to aggressive factors.     

Effect of hepatic collateral hemodynamics on gastric mucosal blood flow in patients with liver cirrhosis

The dependence of the gastric mucosal change in liver cirrhosis on the extrahepatic collaterals is still unknown. Therefore we studied the influence of these collateral hemodynamics on gastric mucosal blood flow and gastric mucosal lesions. The subjects were 23 cirrhotic patients and were divided into two groups by the findings of percutaneous transhepatic portography. The first group consisted of 14 cases whose extrahepatic collaterals were via esophageal varices (group I). The second group included 9 cases having collaterals other than esophageal varices (group II). Multiple red spots were observed in 13 of 14 cases in group I, and two of nine cases in group II. Gastric mucosal blood flow was 2.0±0.9 volts (mean±sd) in group I, 4.0±1.2 in group II. A statistically significant difference was observed between groups I and II. Gastric mucosal blood flow was not significantly correlated with portal venous pressure in group I. It is concluded that, in liver cirrhosis, gastric mucosal blood flow is changeable according to the types of the extrahepatic collaterals.     

Effects of tetrandrine on gastric mucosa and liver in portal hypertensive rats

ＥｆｅｃｔｓｏｆｔｅｔｒａｎｄｒｉｎｅｏｎｇａｓｔｒｉｃｍｕｃｏｓａａｎｄｌｉｖｅｒｉｎｐｏｒｔａｌｈｙｐｅｒｔｅｎｓｉｖｅｒａｔｓＭＵＹｉ，ＳＨＥＮＹａｏＺｏｎｇａｎｄＣＨＵＹｉＦａｎｇＳｕｂｊｅｃｔｈｅａｄｉｎｇｓｌｉｖｅｒｇａｓｔｒｉｃｍ...     

New abdominal collaterals at ultrasound: A clue of progression of portal hypertension

BackgroundAbdominal ultrasound can detect non-invasively the presence of abdominal portal-systemic collaterals in patients with liver cirrhosis. Abdominal portal-systemic collaterals may be protective from the formation and growth of oesophageal varices, but available data are inconclusive.AimWe aimed at investigating the relationship between abdominal portal-systemic collaterals and variceal formation and growth.MethodsWe studied 126 cirrhotic patients without (n = 43) or with small (n = 83) oesophageal varices who entered a protocol of serial ultrasonographic and endoscopic examinations for a median of 55 months. Presence and kind of abdominal portal-systemic collaterals was recorded on first ultrasonography and on each control thereafter.ResultsAt inclusion, abdominal portal-systemic collaterals were found in 19/43 patients without varices and in 23/83 patients with small varices (NS). There was no difference in variceal formation and growth between patients with and without abdominal portal-systemic collaterals at inclusion. However, patients developing new abdominal portal-systemic collaterals during follow-up had a significantly higher rate of variceal formation (56.2% vs. 22.2%; p = 0.024) and growth (52.9% vs. 30.6%; p = 0.041) compared with patients with unchanged ultrasonography.ConclusionsAbdominal collaterals are not protective from the formation or growth of oesophageal varices. Conversely, new abdominal portal-systemic collaterals emergence is a non-invasive clue of formation and progression of varices. Therefore, endoscopy is probably indicated whenever new abdominal portal-systemic collaterals are detected in cirrhotic patients.     

Impaired oxygenation of gastric mucosa in portal hypertension

Increased susceptibility to mucosal damage is a prominent feature of portal hypertensive gastropathy. Since the portal hypertensive gastric mucosa has extensive microvascular changes, we postulated that the increased sensitivity to mucosal damage could have an ischemic basis. We measured distribution of gastric serosal and mucosal oxygenation in a group of portal hypertensive and sham-operated rats, and then studied the effects of intragastric aspirin. In the basal state, gastric mucosa of portal hypertensive rats had significantly reduced oxygenation compared to controls (24±5 vs 45±7 mm Hg PO ₂,P < 0.02), while serosal oxygenation was similar between the two groups. Intragastric aspirin produced significantly greater mucosal damage to portal hypertensive rats and mucosal oxygenation was almost one third that of sham-operated controls. Systemic arterial pressures and oxygenation were similar between the two groups. We conclude that there is impairment of gastric mucosal oxygenation and increased mucosal damage by aspirin in portal hypertensive rats compared with sham-operated controls. These results support our hypothesis that the increased sensitivity of the portal hypertensive mucosa to damage is a consequence of impaired mucosal oxygenation.This study was supported by the Veterans Administration Research Service.This work was presented, in part, at the Plenary Session of the American Association for the Study of Liver Diseases, May 1988, New Orleans, Louisiana.     

善得定对门静脉高压性胃病大鼠胃粘膜灌注的影响

目的 观察善得定对门静脉高压性胃病（ｐｏｒｔａｌ ｈｙｐｅｒｔｅｎｓｉｖｅ ｇａｓｔｏｐａｔｈｙ,ＰＨＧ）大鼠胃粘膜血流最（ｇａｓｔｒｉｃ ｍｕｃｏｓａｌ ｂｌｏｏｄ ｆｏｗ,ＧＭＢＦ）的影响,并对其作用机制作初步探讨。方法 部分结扎大鼠门静脉主干２周后,观察善得定对ＰＨＧ大鼠全身血流动力学,ＧＭＢＦ,门静脉压力（ＰＶＰ）的影响,测定了输注善得定３０ｍｉｎ后ＰＨＧ大鼠血浆胰高糖素,血浆和胃粘膜ＮＯ     

Hemodynamics in the colonic mucosa of rats with dextran sulfate-induced colitis in the early phase

We investigated hemodynamics in the colonic mucosa of rats with experimental colitis induced by the administration of dextran sulfate sodium (DSS). As parameters of hemodynamics, we determined the indices of mucosal hemoglobin concentration (IHb) and mucosal oxygen saturation (ISO₂), measured by reflectance spectrophotometry, and an index of colonic mucosal blood flow (Flow), measured by laser-Doppler flowmetry. In the ascending colon, each parameter was measured by a combination of these methods after 1, 3, 5, 7, and 10 days of DSS administration. Histopathological examination was also performed. IHb in the DSS group increased with time; on the 7th day, the value was 126.9±8.32, while that in the control group was 85.0±4.14, IHb in the DSS group being significantly increased (P<0.02). ISO₂ in the DSS group was lower than that in the control group, and on the 7th day, was significantly lower in the DSS group (25.7±1.34) than in the control group (33.4±1.77) (P<0.01). No changes in Flow were observed in either the DSS or the control group during the administration period, and no significant difference in Flow was found between the two groups. On histopathological examination, we observed a time-dependent increase in the infiltration of inflammatory cells in the ascending colon of rats treated with DSS, but changes such as erosion and ulceration were not found in the superficial layer of the mucosa. No histopathological changes were found in the control animals. In the early phase of the experimental colitis, hemodynamic alterations in the colonic mucosa were already present at the time the slight histopathological changes developed. These observations seemed to indicate the involvement of hemodynamic alterations in the subsequent tissue injury.     

Experimental study of the safety of the selective COX‐2 inhibitor,celecoxib, for gastric mucosa

OBJECTIVE: To compare the gastric mucosal damage induced by a COX‐2 inhibitor, celecoxib, and a conventional NSAID, indomethacin. METHODS: A rat model of NSAID‐induced gastric mucosal damage was prepared for indomethacin and celecoxib separately (n = 8). After gastric damage was induced by 100% ethanol, celecoxib was administered by gastric gavage (n = 8). Gastric mucosal concentrations of 6‐keto‐PGF_1α and TXB₂ and the lesion index (LI) were measured. Morphological changes of the gastric mucosa were assessed under light and scanning electron microscopy. RESULTS: Indomethacin caused marked gastric damage (LI: 13.38 ± 2.06) and significant reduction of the concentrations of 6‐keto‐PGF_1α and TXB₂ (P < 0.01), Celecoxib did not produce necrotic injuries on healthy gastric mucosa (LI: 0), but the mucosal injuries previously induced by ethanol worsened after its administration (LI: 37.19 ± 3.34 vs 19.90 ± 2.28, P < 0.01). CONCLUSIONS: Inhibition of COX‐1 is the major mechanism of NSAIDs in producing gastric mucosal damage. As a selective COX‐2 inhibitor, celecoxib does not produce toxic injuries of the healthy gastric mucosa, and is thus safer than conventional NSAID. However, when administered in the presence of an altered gastric mucosa, gastric injuries were worsened.     

The effects of transjugular intrahepatic portosystemic shunt on portal hypertensive gastropathy

In addition to variceal bleeding, haematemesis may occur due to haemorrhagic gastritis in patients with portal hypertension. This has been known as portal hypertensive gastropathy (PHG). We have evaluated the effects of the transjugular intrahepatic portosystemic shunt (TIPS) on portal venous pressure (PVP) and endoscopic gastric mucosal changes observed in patients with portal hypertension. We performed TIPS in 12 patients with complications due to portal hypertension as follows: variceal bleeding in nine patients (bleeding from oesophageal varices in seven and gastric varices in two), refractory ascites in three and haemorrhage from severe PHG in one. Endoscopic examinations were performed before and after TIPS for all patients. Changes of PVP and gastric mucosal findings on endoscopy were analysed. Before TIPS, PHG was seen in 10 patients. Portal venous pressure decreased from an average of 25.1 ± 8.8 to 17.1 ± 6.2 mmHg after TIPS ( P < 0.005). On endoscopy, PHG improved in nine of 10 patients. Oesophagogastric varices improved in eight of 11 patients. In one patient with massive haematemesis, haemorrhage from severe PHG completely stopped after TIPS. Because TIPS effectively reduced PVP, this procedure appeared to be effective for the treatment of uncontrollable PHG.     

Effects of propranolol on gastric mucosal perfusion and serum gastrin level in cirrhotic patients with portal hypertensive gastropathy

Gastric mucosal hyperemia associated with elevated serum gastrin level has been suggested in cirrhotic patients with portal hypertensive gastropathy (PHG). Clinical evidence has shown that these patients may benefit from propranolol administration. The aim of this study was to investigate effect of propranolol on gastric mucosal perfusion and serum gastrin level in cirrhotic patients with portal hypertensive gastropathy. Gastric mucosal perfusion was assessed by laser Doppler flowmetry. Measurements were performed under basal conditions and after observer-blind administration of propranolol (30–60 mg/day,N=9) or placebo (N=9) for seven days. Placebo had no effect on either gastric mucosal perfusion or serum gastrin level. In contrast, propranolol administration significantly decreased both antrum gastric mucosal perfusion (from 0.88±0.28 to 0.73±0.26 V,P<0.05) and corpus gastric mucosal perfusion (from 0.94±0.35 to 0.78±0.25 V,P<0.05). However, this drug had no effect on serum gastrin level. We conclude that chronic propranolol administration in cirrhotic patients with portal hypertensive gastropathy may reduce gastric mucosal perfusion without changing serum gastrin level.     

Ventricular function and coronary hemodynamics after intravenous nitroglycerin in coronary artery disease.

Left ventricular dynamics as well as systemic and coronary hemodynamics were determined in 14 patients with coronary artery disease (1) under control conditions, (2) under intravenous infusion of nitroglycerin, (3) under continued infusion of nitroglycerin with restored arterial and pulmonary artery pressures induced by the parallel infusion of dextran. Heart rate was kept constant by atrial pacing.Intravenous nitroglycerin infusion resulted in a significant reduction in left ventricular systolic (20 per cent) and end-diastolic pressure (43 per cent), peak $\text{dp}\text{dt}$ (13 per cent), cardiac index (16 per cent), stroke volume index (15 per cent), and stroke work index (30 per cent). Peak (dp/dt/total pressure) increased (15 per cent). Pulmonary vascular resistance markedly decreased (29 per cent), whereas total peripheral resistance did not change significantly (?3 per cent). Both coronary blood flow of the left ventricle (13 per cent) and myocardial oxygen consumption (15 per cent) decreased parallel to the reduction in preload and afterload. The action of nitroglycerin at restored left ventricular and pulmonary artery pressures was characterized by increase in peak $\text{dp}\text{dt}$ (12 per cent), peak ($\text{dp}\text{dt}$ total pressure) (18 per cent), cardiac index (13 per cent), stroke volume index (14 per cent), and stroke work index (10 per cent). Both coronary blood flow (28 per cent) and myocardial oxygen consumption (21 per cent) increased parallel to the enhancement of ventricular performance.The results demonstrate that intravenous nitroglycerin produces effective diastolic and systolic unloading of the heart associated with reduction in myocardial oxygen consumption and in coronary blood flow. There was marked vascular pooling which quantitatively averaged 437 ± 128 ml. This occurred concomitant with a 43 per cent decrease in left ventricular end-diastolic pressure or a 20 per cent decrease in peak systolic pressure. Significant coronary dilating properties of nitroglycerin could not be detected in these coronary patients. The increase in left ventricular contractility indices at restored pressure suggests a moderate but significant positive inotropic effect of nitroglycerin.     

Nitroglycerin improves the hemodynamic response to vasopressin in portal hypertension

This study was designed to investigate whether the addition of nitroglycerin to vasopressin infusion could avoid the deleterious systemic effects of vasopressin while maintaining or enhancing the therapeutic benefits of portal pressure reduction. The effect of nitroglycerin on splanchnic and systemic hemodynamics was studied in cirrhotic patients and portal hypertensive dogs receiving i.v. vasopressin. During i.v vasopressin infusion (0.4 units per min), the cardiac output decreased in patients by 14% from 7.6 +/- 0.9 (mean +/- S.E.) to 6.5 +/- 0.7 liters per min, p less than 0.01, the mean arterial pressure increased 21% from 87 +/- 2 to 105 +/- 4, p less than 0.01, and the heart rate decreased 11% from 79 +/- 3 to 71 +/- 3, p less than 0.01. The administration of sublingual nitroglycerin (0.4 mg) returned all the systemic hemodynamic parameters to baseline values. In dogs, vasopressin infusion significantly reduced portal pressure and flow while increasing portal venous resistance. Nitroglycerin when added to the vasopressin infusion reduced portal venous resistance and further decreased portal pressure in dogs. In patients, vasopressin reduced the hepatic blood flow (44%), wedged hepatic venous pressure (11%), and the gradient between wedged and free hepatic venous pressures (23%). Nitroglycerin administration caused a further reduction of the wedged hepatic venous pressure (23.6 +/- 2.3 to 21.1 +/- 2.0, 11%, p less than 0.01). There was a small but not significant further decline (7%) in the hepatic venous pressure gradient. These results provide evidence that the addition of nitroglycerin to an i.v. infusion of vasopressin reversed the detrimental effects of vasopressin while preserving the beneficial effects.