Aging augments renal vasoconstriction during exercise and local muscle heating

• Published in: The FASEB journal Vol. 21; no. 5; p. A569
• Main Authors: Kuipers, Nathan T., Sauder, Charity L., Kearney, Matthew L., Ray, Chester A.
• Format: Journal Article
• Language: English
• Published: Federation of American Societies for Experimental Biology 01-04-2007
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.5.A569-c

The purpose of the present study was to examine the interactive effect of aging and forearm muscle heating on renal vascular responses to ischemic isometric handgrip (IHG). A tube lined water‐perfused sleeve was used to heat the forearm in eleven young (25±1 yr) and six older (66±2 yr) subjects. The experimental protocol was performed before and after heating. The experimental protocol was: 3‐min baseline, 1 min of ischemia, ischemic IHG to fatigue, and 2 min of postexercise muscle ischemia (PEMI). Muscle temperature (intramuscular thermistor) was 34°C and 39°C during normothermia and heating, respectively. The older subjects had significantly higher renal blood velocity (RBV; Doppler ultrasound) and renal vascular conductance (RVC) compared to the young subjects at rest. Heating had no effect on RBV and RVC at rest in both groups. Heating augmented renal vasoconstriction in both groups during ischemic IHG. Older subjects had greater decreases in RBV (Δ −35±8 vs. −10±2 cm/sec) and RVC (Δ −0.6±0.2 vs. −0.24±0.03 a.u.) at fatigue compared to the young in the heat trial. In contrast, the increase in RBV and RVC were comparable across age groups and temperatures during PEMI. These results indicate that heating of muscle elicits greater mechanoreceptor‐mediated renal vasoconstriction in the older subjects during exercise. NIH DC006459, HL077670, MO1RR10732, & NSBRI CA00404