Changes in in vivo renal artery hemodynamics after exercise training

Abstract

Recent studies on the effects of exercise on the kidney have identified strain‐specific responses of shear dependent endothelial enzymes, endothelial nitric oxide synthase (eNOS) and extracellular superoxide dismutase (ECSOD). Here we investigated the effect of 12 weeks voluntary wheel running (VWR) (~3 km/day @wk 12) on in vivo renal artery hemodynamics in male Fisher 344 rat compared to sedentary controls (both n=6). We measured peak and mean flow velocity (PFV and MBV, respectively) using a 10 MHz Doppler probe and workstation 24h after withdrawal from VWR, under isoflurane anesthesia. After Doppler acquisition, the right renal artery diameter (RAD) was measured ex vivo to calculate peak and mean blood flow (PBF and MBF, respectively) and peak and mean shear rate. RAD, PBF, and MBF significantly decreased after ET (0.43±0.08 vs. 0.35±0.05 mm, 4.43±1.47 vs. 2.08±0.87 ml/min, 1.66±0.56 vs. 0.77±0.47 ml/min, respectively, p<0.05). However, despite the fall in PBF/MBF there were no changes observed in PFV, MBV, or shear rate. Thus, 12w of mild exercise (VWR) causes persistent reduction in renal blood flow and vascular remodeling in the renal artery. There was no fall in shear rate entering the kidney, however, which may contribute to the preservation/enhancement of renal cortical eNOS and ECSOD in the F344, which contrasts with the Sprague Dawley, where VWR reduces eNOS/ECSOD.Funded by NIH R01 HL077224 and DK56843