Human studies have recently demonstrated a significant natriuretic effect of GLP-1 when the extracellular fluid volume (ECFV) is expanded by intravenous sodium-loading; in these studies, there was a suppression of ANG II with no change in net renal hemodynamics, pointing to a tubular mechanism for reduced NaCl reabsorption secondary to the ANG II suppression. In the current randomized and controlled study, investigators aim to test the hypothesis that GLP-1's suppression of ANG II and natriuretic action increase medullary perfusion and decrease oxygen consumption, leading to higher tissue oxygenation. Thus, contributing to the renoprotective action of GLP-1.~Under fixed sodium intake for 4 days before each study day, 10 healthy male participants will be investigated during a 1-hour infusion of GLP-1 (1.5 pmol/kg/min) or vehicle together with an intravenous infusion of 0.9% NaCl. Interleaved measurements of RAF, oxygenation (T2*) and perfusion by arterial spin labeling in the renal cortex and medulla at fixed time points will be conducted, using Magnetic Resonance Imaging (MRI).
This study investigates the hypothesis, that GLP-1's suppression of ANG II and natriuretic action increase medullary perfusion and decrease oxygen consumption, leading to higher tissue oxygenation.