THE EFFECTS OF GLUCAGON, SECRETIN, PANCREOZYMIN AND PENTAGASTRIN ON THE HEPATIC ARTERIAL VASCULAR BED OF THE DOG

Abstract

1 The sympathetically-innervated arterial vascular bed of the dog's liver was perfused from a femoral artery. Arterial blood flow and perfusion pressure were monitored continuously and the hepatic arterial vascular resistance (HAVR) calculated from these measurements. 2 Commercial preparations of secretin, pancreozymin, glucagon and pentagastrin were administered by intra-arterial (i.a.) injection and infusion. 3 Secretin and pancreozymin by injection caused dose-dependent hepatic arterial vasodilatation, and on a molar basis were both more potent than glucagon or pentagastrin. 4 Intra-arterial infusions of secretin and pancreozymin caused hepatic arterial vasodilatation at calculated blood concentrations close to those measured under physiological conditions by other investigators. The vasodilatation was of the same duration as that of the hormone infusions. 5 Pentagastrin by i.a. injection caused dose-dependent hepatic arterial vasodilatation; by i.a. infusion, vasodilatation occurred but there was marked ‘escape’ from the effects during the continued infusion. 6 As reported previously, glucagon by injection caused dose-dependent hepatic arterial vasodilatation of long duration; by infusion, glucagon caused vasodilatation that persisted after the cessation of the infusion. 7 Glucagon infused i.a., inhibited the vasoconstrictor effects of i.a. noradrenaline, over the same range of infusions that caused hepatic arterial vasodilatation. 8 Secretin or pancreozymin did not antagonize the effects of noradrenaline on the hepatic arterial vascular bed at any doses used. 9 Pentagastrin did not antagonize the vasoconstrictor effect of noradrenaline whether hepatic arterial vasodilatation resulted from the pentagastrin infusion, or not. 10 These results are discussed with respect to the possible control of the hepatic arterial vascular bed by gastrointestinal hormones.