Hemodynamic Actions of Pentagastrin

Pentagastrin (Peptavlon, ICI 50123) is known as a powerful stimulator of gastric acid secretion. Several authors have demonstrated a close relationship between gastric acid secretion and gastric blood flow. In this study the general hemodynamic properties of pentagastrin were investigated qualitatively and quantitatively. The study was performed on anesthetized mongrel dogs. Blood flow was assessed with non-cannulating electromagnetic flow probes. Pentagastrin was injected intravenously at intervals of 2 min in amounts between 1 ng and 8192 ng/kg, following a logarithmic scale. Pentagastrin dose-dependently increased splanchnic blood flow in a reversed U-shaped manner. The major vasoactivity occurred in two organ areas--the gastric area and the pancreatico-duodenal area. Pentagastrin increased blood flow in these areas to 300% and 350% of initial value, respectively, at a dose of 2-4 microgram/kg. Since heart rate, cardiac output, and arterial pressure were not influenced, pentagastrin had no general hemodynamic effect. This was confirmed by blood flow measurements in the renal a., common carotid a., and femoral a. It was therefore concluded that the splanchnic blood flow increase was due to an extreme decrease of splanchnic vascular resistance.