OBJECTIVE: Collateral vascular responsiveness to vasoconstrictors may be crucial in the management of acute variceal bleeding. In an in situ perfusion model, arginine vasopressin (AVP) has been shown to cause a direct vasoconstrictive effect on portal-systemic collaterals and this effect is enhanced by preincubation of indomethacin (INDO). The purpose of this study was to investigate the effects of chronic INDO administration on the portal-systemic collateral responsiveness to AVP and the degree of portal-systemic shunting in portal hypertensive rats. MATERIAL AND METHODS: Rats with partial portal vein ligation randomly received daily subcutaneous injections with INDO (5 mg/kg) or distilled water (control group) 2 days prior to until 7 days after ligation. Systemic and portal hemodynamics was evaluated on the 8th day. Using an in situ collateral perfusion model, AVP (10(-10)-10(-7) M) at a constant flow rate (20 ml/min) was applied. In another series, Krebs solution with different flow rates (5-30 ml/min) was used to obtain flow-pressure curves: the slopes represent collateral vascular resistances--the higher resistances indicate fewer collaterals. RESULTS: Mean arterial pressure and portal pressure were not significantly different between the INDO-treated group and the control group (p>0.05). In the first series of experiments, INDO treatment increased the collateral perfusion pressure to AVP at 10(-8) M, 3x10(-8) M, and 10(-7) M (p<0.05). In the second series, INDO did not change collateral vascular resistance, which suggests that the degree of shunting was not altered. CONCLUSIONS: Chronic INDO treatment improves the collateral vascular responsiveness to AVP without ameliorating portal-systemic shunting in portal hypertensive rats.
OBJECTIVE: Collateral vascular responsiveness to vasoconstrictors may be crucial in the management of acute variceal bleeding. In an in situ perfusion model, arginine vasopressin (AVP) has been shown to cause a direct vasoconstrictive effect on portal-systemic collaterals and this effect is enhanced by preincubation of indomethacin (INDO). The purpose of this study was to investigate the effects of chronic INDO administration on the portal-systemic collateral responsiveness to AVP and the degree of portal-systemic shunting in portal hypertensiverats. MATERIAL AND METHODS:Rats with partial portal vein ligation randomly received daily subcutaneous injections with INDO (5 mg/kg) or distilled water (control group) 2 days prior to until 7 days after ligation. Systemic and portal hemodynamics was evaluated on the 8th day. Using an in situ collateral perfusion model, AVP (10(-10)-10(-7) M) at a constant flow rate (20 ml/min) was applied. In another series, Krebs solution with different flow rates (5-30 ml/min) was used to obtain flow-pressure curves: the slopes represent collateral vascular resistances--the higher resistances indicate fewer collaterals. RESULTS: Mean arterial pressure and portal pressure were not significantly different between the INDO-treated group and the control group (p>0.05). In the first series of experiments, INDO treatment increased the collateral perfusion pressure to AVP at 10(-8) M, 3x10(-8) M, and 10(-7) M (p<0.05). In the second series, INDO did not change collateral vascular resistance, which suggests that the degree of shunting was not altered. CONCLUSIONS: Chronic INDO treatment improves the collateral vascular responsiveness to AVP without ameliorating portal-systemic shunting in portal hypertensiverats.
Authors: Francisco X Eizayaga; Omar Aguejouf; Vanessa Desplat; Philippe Belon; Christian Doutremepuich Journal: World J Gastroenterol Date: 2007-10-14 Impact factor: 5.742