Voluntary exercise training attenuates the enhanced sympathetic responses to muscle mechanoreflex activation in spontaneously hypertensive rats

Abstract

Exercise training has beneficial effects on cardiovascular diseases such as hypertension. However, the underlying mechanisms remain to be elucidated. The purpose of this study was to examine whether regular exercise reduces abnormally exaggerated skeletal muscle mechanoreflex function in hypertension. Changes in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) to stimulation of the muscle mechanoreflex were assessed in untrained normotensive Wistar‐Kyoto rats (WKYUT; n = 6), exercise trained WKY (WKYET; n = 7; housed in cage with running wheel for 3 months), untrained spontaneously hypertensive rats (SHRUT; n = 3) and exercise trained SHR (SHRET; n = 7). There was no difference between WKYUT and WKYET in RSNA (40±11 vs. 47±11 %, respectively) and MAP (7.5±4.0 vs. 8.0±4.2 mmHg, respectively) responses to stimulating the mechanoreflex by passively stretching hindlimb muscles. Voluntary wheel running (3 months) significantly attenuated sympathetic responses to mechanoreflex stimulation in SHRET compared with SHRUT (35±12 vs. 113±22 %, respectively, P<0.01). A similar MAP response profile was likewise produced (14±3 vs. 33±22 mmHg, respectively). In conclusion, our data provide the first direct evidence that voluntary exercise ameliorates abnormal mechanoreflex overactivity in hypertension. Supported by NIH HL‐088422 and HL‐113738