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Overactivation of muscle mechanoreflex in human hypertension
Author(s) -
Velasco Alejandro,
Wang Zhongyun,
Arbique Debbie,
Smith Scott,
Mitchell Jere,
Vongpatanasin Wanpen
Publication year - 2015
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.29.1_supplement.1055.12
Subject(s) - medicine , cardiology , electromyography , contraction (grammar) , blood pressure , endocrinology , physical medicine and rehabilitation
Our previous study in patients with mild essential hypertension demonstrated that moderate level rhythmic handgrip (RHG) at 30% maximal voluntary contraction (MVC), which typically had no effect on sympathetic nerve activity (SNA) in healthy normotensive subjects, evoked asympathoexcitatory response in hypertensive subjects. This finding indirectly suggested that mechanoreflex function was enhanced in hypertension. However, mechanoreflex function has not been directly assessed in hypertensive patients. Accordingly, we measured SNA with intraneural microelectrodes in 5 subjects with untreated hypertension (HTN) and 6 age‐matched normotensive controls (NT) during passive arm cycling (PAC). PAC was used to preferentially stimulate the mechanoreflex. Surface electromyography was monitored during arm cycling to avoid inadvertent muscle contraction. We found that SNA increased significantly in HTN compared to NT within the first minute of PAC, which was sustained at 3 minutes (27±10 vs. 2±6% total activity, p < 0.05). The increase in SNA was accompanied by a significant increase in mean arterial pressure (MAP) from 102±4 to 106±3 mmHg in the HTN group (p <0.05), while MAP remained unchanged in NT group (96±3 vs. 96±3 mmHg, p = NS). Rhythmic handgrip at 30% MVC also induced greater increases in SNA in the HTN than NT group (46±14 vs. ‐1±6% total activity, p <0.05). Thus, our data represent the first direct evidence for enhanced mechanoreflex function in human hypertension.