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The sympathetic response to activation of the skeletal muscle mechanoreflex is enhanced in spontaneously hypertensive rats
Author(s) -
Mizuno Masaki,
Murphy Megan N.,
Mitchell Jere H.,
Smith Scott A.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.619.5
Subject(s) - medicine , skeletal muscle , endocrinology , blood pressure , triceps surae muscle , sympathetic nerve , afferent , hindlimb , anatomy
Evidence suggests that the exaggerated cardiovascular response to exercise in hypertension is mediated, in part, by the skeletal muscle mechanoreflex (MMR). However, the mechanism by which the MMR produces this heightened response remains undetermined. Normally when stimulated, the MMR induces acute elevations in sympathetic nerve activity (SNA). Therefore, we hypothesized that the enhanced cardiovascular response to MMR activation in hypertension results from abnormally exaggerated increases in SNA. To test this hypothesis, mechanically sensitive afferent fibers (associated with the MMR) were selectively activated in normotensive Wistar‐Kyoto (WKY, n = 8) and spontaneously hypertensive (SHR, n = 6) decerebrate rats by passively stretching the triceps surae muscles of the right hindlimb (approximately 1000 g of tension developed). Passive stretch induced greater increases in renal SNA in SHR as compared to WKY (change from baseline = 139.4 ± 32.9 vs. 46.4 ± 9.5 %, respectively, P<0.05) as well as mean arterial pressure (change from baseline = 39.4 ± 12.3 vs. 13.6 ± 2.8 mmHg, respectively, P < 0.05). The results suggest that the exaggerated arterial pressure response to activation of the MMR in hypertension is mediated by abnormal augmentations in SNA. Supported by NIH HL‐088422