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Increasing nitric oxide within the nucleus tractus solitarius attenuates skeletal muscle mechanoreflex overactivity in hypertension
Author(s) -
Leal Anna K,
Williams Maurice A,
Garry Mary G,
Mitchell Jere H,
Smith Scott A
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.21.6.a892-c
Evidence suggests the stretch‐sensitive skeletal muscle mechanoreflex (MMR) contributes significantly to the exaggerated blood pressure response to exercise in hypertension. The mechanism of this MMR overactivity is not clear. Sensory information generated from the MMR is processed within the nucleus tractus solitarius (NTS). Normally, endogenously expressed nitric oxide (NO) within the NTS attenuates the pressor response elicited by the MMR. Therefore, we hypothesized that the exaggerated increase in blood pressure mediated by the MMR in hypertension is due to a decrease in the availability of NO within the NTS. We selectively activated the MMR by passively stretching hindlimb skeletal muscle before and after the dialysis of the NO precursor L‐arginine (1.0 μM) in the NTS of male normotensive Wistar Kyoto (WKY; n=4) and spontaneously hypertensive (SHR; n=5) rats. Passive stretch resulted in larger increases in mean arterial pressure in SHR (81±20 mmHg) than WKY (13±2 mmHg). In both groups, dialysis of L‐arginine in the NTS attenuated the pressor response to stretch. However, the magnitude of this reduction was greater in SHR (−35±10 mmHg) than WKY (−8±1 mmHg). Given that increasing NO in the NTS partially corrected the exaggerated pressor response to stretch in SHR, it is suggested that decreases in NO availability within the NTS contribute to MMR overactivity in hypertension. Supported by AHA BGIA‐0565139Y.