The effect of vasopressin on organ blood flow in an endotoxin-induced rabbit shock model.

The effects of vasopressin on the vasculature differ from those of other vasopressors, and its effects on the coronary artery remain debatable. This study was undertaken to examine the effects of vasopressin in a rabbit endotoxin-induced shock model and to compare these effects with those of norepinephrine. Thirty rabbits were divided into four study groups: a normal control group (group I, n = 5), a shock control group (group II, n = 5), a vasopressin group (group III, n = 10), and a norepinephrine group (group IV, n = 10). Shock was induced by intravenously infusing lipopolysaccharide (Escherichia coli O111:B4) in groups II, III, and IV. In groups III and IV, systemic blood pressure was maintained to the level of group I by adjusting vasopressin and norepinephrine doses. Left ventricle, right ventricle, ventricular septum, kidney, liver, spleen, and skeletal muscle blood flows were measured using radioisotope tagged microspheres at baseline and 2 h after initial blood flow measurement. No difference in organ blood flows were observed between groups I and II, and coronary blood flow in the left ventricle, right ventricle, and ventricular septum was similar in all study groups. However, renal blood flow was significantly lower in group IV than in group III (p < .05) and hepatic arterial blood flow was significantly lower in group III than in group IV (p < .05). Thus, effect of vasopressin on organ blood flow is organ dependent. Vasopressin increased renal blood flow and decreased hepatic arterial blood flow in this endotoxin-induced shock model, whereas norepinephrine did not. However, coronary blood flow was not changed by shock status or vasopressor type.