A Potent Drug Combination for Producing Constriction of the Superior Mesenteric Artery and its Branches

Abstract

The use of epinephrine in renal arteriography to bring about constriction of the normal renal vessels and relative enhancement of tumor vascularity is now an accepted technic (1, 6). On the other hand, epinephrine injected into the superior mesenteric artery fails to produce consistent vasoconstriction and is of uncertain value in improving visualization of pathologic vessels in the bowel and mesenteric bed (5, 7). It has recently been shown by one of us that infusions of epinephrine into the superior mesenteric artery of anesthetized cats may actually increase mesenteric blood flow, after a brief period of reduced flow (11). After induction of “beta-adrenergic blockade” of the animal with intravenous propranolol, however, an epinephrine infusion into the superior mesenteric artery causes a sustained reduction in mesenteric blood flow throughout the period of the infusion. These observations suggested that administration of epinephrine clinically into the superior mesenteric artery in the presence of beta-adrenergic blockade (i.e., after pretreatment with propranolol), might more consistently induce vasoconstriction in the mesenteric bed. The following studies were designed to test this hypothesis. Methods and Results Dogs were anesthetized with intravenous pentobarbital sodium, 30 mg/kg. Superior mesenteric arterial blood flow was measured following laparotomy in 5 animals, by the electromagnetic method using a 400 c.p.s. flow channel and a noncannulating probe. After application of the probe to the superior mesenteric artery, a catheter was introduced into a femoral artery, and its tip was advanced into the superior mesenteric artery under fluoroscopic control. Continuous infusions of epinephrine (5 μg per minute) into the superior mesenteric artery via the catheter, produced effects on mesenteric blood flow which were identical to those previously observed in the cat, i.e., a transient decrease in superior mesenteric blood flow, followed by an actual increase in mesenteric flow above base-line levels while the infusion continued (11). On the other hand, after induction of beta-adrenergic blockade by the infusion of 2 mg propranolol directly into the superior mesenteric artery, the infusion of epinephrine resulted in a sustained reduction of flow in the superior mesenteric artery (Fig. 1). The physiological aspects of these studies will be reported in more detail elsewhere. Superior mesenteric angiography was also performed, as follows: 1. Before epinephrine infusion (Fig. 2, A). 2. During a superior mesenteric arterial infusion of epinephrine (Fig. 2, B). 3. During an epinephrine infusion which was begun after the induction of beta-adrenergic blockade with 2 mg propranolol (see above; also Fig. 2, C).