Glucagon induced functional changes of isolated perfused rat kidney

The influence of glucagon on renal function and hemodynamics was studied on isolated perfused rat kidneys. During perfusion with solutions containing no vasoactive substances glucagon increased total renal perfusion flow, while the GFR remained unchanged. The autoregulation of blood flow under these conditions was completely abolished. Na-excretion was slightly reduced under the action of glucagon, due to an increased fractional Na-reabsorption. However, increased fractional Na-reabsorption was not due to a direct influence of glucagon on tubular transport mechanism as comparison of TNa at identical Na-loads demonstrated. In presence of angiotensin II renal perfusion flow was markedly reduced and doubled almost after starting glucagon infusion. GFR under these conditions rose by about 100%. It is concluded from the results that changes of kidney function following glucagon infusion are mainly due to a reduced vascular resistance.