PROTECTION OF ENDOTHELIAL DAMAGE AND SYSTEMIC SHOCK BY BENIDIPINE, A CALCIUM-ANTAGONIST, IN RATS SUBJECTED TO SPLANCHNIC ISCHEMIA AND REPERFUSION

Splanchnic artery occlusion (SAO) with subsequent reperfusion elicits a severe form of circulatory shock. To study the possible involvement of Ca2+ overload in this shock state, we have examined the effects of benidipine, a novel long-acting calcium antagonist, in a rat model of SAO shock, focusing on endothelial damage. Pentobarbital-anesthetized rats were subjected to 90-min occlusion of both the celiac and superior mesenteric arteries, followed by reperfusion. Rats given only the vehicle for benidipine developed hypotension following reperfusion, and only 7 of 16 rats (44%) survived 2 hr of reperfusion. In isolated superior mesenteric rings from SAO-shock rats, the EDRF-dependent dilator response to acetylcholine (ACh) (100 nM) was severely depressed (9% vs. 97% in control artery rings, P < 0.001), whereas the EDRF-independent dilator response to acidified NaNO2 (100-mu-M) was unchanged. By contrast, 90% (9 of 10, P < 0.05) rats treated with benidipine 45 min postocclusion (3-mu-g/kg, i.v.) survived 2 hr, and the dilator response to ACh was markedly improved (49% of initial, P < 0.001). SAO-shock rats treated with benidipine also exhibited significantly attenuated accumulation of free amino-nitrogenous compounds (5.5 vs. 7.9 U/ml, P < 0.05) and myocardial depressant factor (34 vs. 62 U/ml, P < 0.001). These results suggest that endothelial damage plays a role in the pathogenesis of shock following bowel ischemia and reperfusion and that Ca2+-entry blockade improves endothelial function, which is involved in the amelioration of the shock state.