Restoration of renal and mesenteric hemodynamics by felodipine in a canine model of hemorrhagic shock.

The effects of felodipine, a dihydropyridine vasodilator, were investigated in a canine model of hemorrhagic shock. Mongrel dogs were anesthetized with sodium pentobarbital and subjected to hemorrhagic shock by allowing the animals to bleed into a reservoir. After maintaining the hypotensive state (mean blood pressure: 40-60 mm Hg) for a period of 150 min, the blood was reinfused and the recovery of the various parameters were monitored for an additional 120 min. These studies were conducted in three different groups of dogs: A) controls, B) felodipine, 0.01 mumol/kg i.v., was administered before reinfusion of the blood and C) felodipine, 0.01 mumol/kg i.v., was administered prior to hemorrhage. In all the three groups, arterial blood pressure returned essentially to pre-hemorrhage levels following reinfusion; in the groups A and B, there was about 80% recovery of the cardiac output, whereas in the group C cardiac output returned completely to the basal values. During the hemorrhagic hypotension, renal and mesenteric blood flows fell to 10-40% of the basal values in all the three groups. In the control group A, there was only 40 to 45% recovery in the renal and mesenteric flows after reinfusion indicating sustained vasoconstriction in these vascular beds. Felodipine administration before reinfusion (group B), resulted in 70% to 90% recovery in the renal and mesenteric flows after reinfusion. In the group C (felodipine before hemorrhage) there was 85% recovery in the renal flow and 100% in the mesenteric blood flow after reinfusion. The observations made in this study suggest that felodipine, an arteriolar dilator, may be clinically useful in restoring organ blood flows which are seriously compromised during the hemorrhagic shock.