Thesis (M.Sc.)--Chulalongkorn University, 1990

Effects of L- arginine (ARG) infusion on renal and systemic hemodynamic were studied in 10 anesthetized dogs. The experiment was performed in two groups of dogs. Group 1 dogs (n = 5) received intravenous ARG at 2.5 mmol/kg followed by indomethacin (IND) injection (10 mg/kg) and was rechallenged with ARG at the same amount. Group 2 dogs (n = 5) received, intravenous ARG at 5 mmol/kg followed by IND injection (10 mg/kg) and later infused with ARG at the same dose. In group 1 the first ARG infusion caused no changes in renal and systemic hemodynamic comparing with the control period. During the second ARG infusion the glomerular filtration rate (GFR) and the renal plasma flow (RPF) were increased by 42 %. and M-7% respectively (p< .05 for both) when compared with IND-treated period. In group 2, the first ARG infusion increased cardiac output (CO) (p < .05) and decreased total peripheral resistance (TPR) (p< .05) whereas there were no significant changes in GFR and RPF. The second ARG infusion induced acute rise of both GFR and RPF approximately two folds (p<0.05 for both), comparing with IND-treated period. CO was also increased significantly (p<.05). These results indicate that an acute ARG loading induces renal and systemic vasodilatation in a dose dependent manner despite IND effect and would indicate that increased renal hemodynamic are not prostaglandin-mediated.