Muscle sympathetic nerve activity responses to dynamic passive muscle stretch in humans

Jian Cui, Cheryl Blaha, Raman Moradkhan, Kristen S. Gray and Lawrence I. Sinoway

It is suggested that mechanoreceptors in muscle play an important role in the exercise pressor reflex. However, it has not been verified whether isolated stimulation of the mechanoreceptors can induce responses in muscle sympathetic nerve activity (MSNA) in young healthy individuals. This study tests the hypothesis that passive stretch of muscle can evoke an increase in MSNA in healthy individuals. The results showed MSNA, mean blood pressure and heart rate increased transiently but significantly from the prior stretch baseline.  Similar response patterns were observed during active muscle contractions. The authors conclude that the present data show that MSNA responses to isolated stimulation of mechanoreceptors are measurable. Because of baroreflex engagement, the magnitude of the response is small and transient, and the haemodynamic consequences using this protocol may be limited.

The Journal of Physiology, 576.2 pp 625-634

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