Renal neurohormonal and vascular responses to dynamic exercise in humans

Abstract

Effects of graded supine dynamic exercise (30, 60, and 80-90% of maximal physical capacity, i.e., work loads of 69, 132, and 188 W) on renal vascular resistance (RVR); renal sympathetic nerve activity [assessed by the renal venous overflow of norepinephrine (NE)]; renal overflows of dopamine (DA), immunoreactive neuropeptide Y (NPY-LI), and renin; as well as plasma concentrations of angiotensin-(1-8)-octapeptide (ANG II) were evaluated in eight healthy male volunteers. Exercise evoked stimulus-dependent and marked elevations of RVR, arterial NE, epinephrine (Epi), and DA. RVR increased by 140% and the renal overflows of NE and DA increased by 1,331 and 179%, respectively, at 188 W. A net removal of NPY-LI at rest turned into a small net renal overflow, which correlated with increases in RVR at 188 W. Increases in renin release (+1,200% at 188 W) correlated with increases in renal NE and DA overflows and with arterial Epi levels. Arterial ANG II levels increased stimulus dependently (by 264% at 188 W) and correlated more closely with increases in RVR than did other variables. Thus dynamic exercise is a potent stimulus for renal nerve activation in humans, and renal sympathetic nerve activity may contribute to increased RVR both directly (NE and, at exhaustive work loads, possibly NPY) and indirectly (via renin-mediated ANG II formation).

Sympathetic vasomotor control does not explain the change in femoral artery shear rate pattern during arm-crank exercise

“…However, the exercise bout was performed at 50% of the individual maximal work load, leading to an approximately fivefold increase in oxygen uptake. Previous studies demonstrated that much lower intensity levels than those used in the present study are associated with a marked increase in sympathetic nerve activity (15,24). Therefore, we assume that our exercise protocol induced a significant increase in leg sympathetic nerve activity in controls.…”

Influence of sedentary versus physically active conditions on regulation of plasma renin activity and vasopressin

“…Wheels were removed from the cages of physically active animals just prior to surgery. This was done to reduce the effects of an acute bout of exercise on AVP and ANG II levels (51,53). Animals remained in the experiment room during the 2-day recovery period to acclimate to the experimental surroundings.…”

Dynamic Exercise Attenuates Spontaneous Baroreceptor Reflex Sensitivity in Conscious Rats

“…We demonstrated previously that AngII, acting within the NTS, depresses the baroreceptor reflex via activation of endothelial nitric oxide synthase (eNOS; Paton et al 2001) and that endogenous eNOS activity within the NTS chronically depressed the sBRS in conscious rats (Waki et al 2003). Interestingly, circulating AngII increases during dynamic exercise (Tidgren et al 1991;Stebbins & Symons, 1995). Since circulating AngII may affect NTS neurones via eNOS activation (Paton et al 2001), we hypothesised that eNOS activity within NTS is one factor determining baroreceptor reflex function during dynamic exercise.…”