Postprandial regulation of renal hemodynamics: role of pancreatic glucagon

Abstract

The quantitative importance of glucagon in mediating protein-induced increases in renal blood flow (RBF) and glomerular filtration rate (GFR) during the postprandial state was ascertained. Six chronically instrumented conscious dogs were each subjected to 4 protocols: normal protein control meal (C); high protein meat meal (M); somatostatin infusion and meat (S + M); and glucagon infusion. C produced small increases in RBF (12 .+-. 2%) and GFR (14 .+-. 2%) without changing arterial plasma glucagon. M produced marked increases in RBF (38 .+-. 4%) GFR (41 .+-. 5%), and glucagon (from 23.3 .+-. 3.6 to 73.3 .+-. 7.1 pg/ml) over a 3-h period. During S + M, RBF and GFR failed to increase while glucagon was suppressed by 36 .+-. 8% over a 2-h period. When S was stopped, glucagon rose to 100 .+-. 13.9 pg/ml over the next hour, yet RBF and GFR increased by only 14 .+-. 4 and 10 .+-. 3%, respectively. Glucagon infusion (3 ng .cntdot. kg-1 .cntdot. min-1, i.v.) markedly elevated plasma glucagon to 131.6 .+-. 27.3 pg/ml, yet neither RBF nor GFR significantly changed. While a protein-rich meat meal does elevate arterial plasma glucagon, the rise is not great enough to elicit significant changes in renal hemodynamics. Elevated plasma levels of glucagon cannot account for protein-mediated increases in RBF and GFR during the postprandial state.