THE VASODILATOR ACTIONS OF ISOPRENALINE, HISTAMINE, PROSTAGLANDIN E2, GLUCAGON AND SECRETIN ON THE HEPATIC ARTERIAL VASCULAR BED OF THE DOG

Abstract

The sympathetically‐innervated arterial vascular bed of the dog's liver was perfused from a femoral artery. Arterial blood flow and perfusion pressure were measured continuously, and the hepatic arterial vascular resistance calculated. The preparation provided a means of assessing hepatic arterial vasodilatation quantitatively. Isoprenaline, histamine, prostaglandin E2, glucagon and secretin were injected intra‐arterially and all evoked dose‐dependent vasodilatation of the hepatic arterial vascular bed. The maximum reduction in the calculated hepatic arterial vascular resistance of 37–38% was the same for each of the five substances. Comparisons on a weight basis revealed that prostaglandin E2 was the most potent, followed in potency order by secretin, isoprenaline, histamine and glucagon. Comparisons on a molar basis showed that secretin and prostaglandin E2 were intrinsically considerably more potent than isoprenaline, histamine or glucagon. The onset of the vasodilatator responses to secretin, isoprenaline, histamine and prostaglandin E2 was rapid, and the duration of their actions was brief. The onset of the vasodilator effects of glucagon was slow and its duration of action very prolonged. The implications of these observations with respect to the physiological control of the hepatic arterial vascular bed of the dog are discussed. 1976 British Pharmacological Society