Dynamic changes in blood flow and oxygen consumption in the portal-drained viscera of growing pigs receiving acute administration of l-arginine

Abstract

This study tested the hypothesis that an increase in arginine concentration in the portal vein may affect blood flow and oxygen consumption in the portal-drained viscera (PDV) of swine. Eight barrows (70 kg body weight) were surgically fitted with chronic catheters in the portal vein, ileal vein, and carotid artery. Thirteen days after the surgery, pigs that had been fasted for 12 h were randomly allocated to receive administration of either L-alanine (103 mg/kg body weight, isonitrogenous control) or L-arginine-HCl (61 mg/kg body weight) via the portal vein. Portal vein blood flow (PVBF) was measured with infusion of p-aminohippuric acid into the ileal vein, and blood samples were simultaneously obtained every 0.5 h for 4 h. Compared with the control, arginine infusion increased PVBF at 30-90 min after infusion but decreased PDV oxygen consumption at 60-150 min after infusion (P < 0.05). Plasma concentrations of glutamate at infusion times of 180-240 min and of arginine at infusion times of 60-240 min in arginine-infused pigs were higher than those for the control group (P < 0.05). Plasma concentrations of insulin and glucagon at the infusion times of 30-90 min were higher and of free fatty acids at the infusion times of 60-120 min were lower than those for the control pigs (P < 0.05). These results indicate that increasing arginine concentration in the portal vein enhances PDV blood flow, reduces PDV oxygen consumption, and beneficially alters the metabolic profile in swine, an established animal model for studying human nutrition and metabolism.