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The Journal of Clinical Investigation logoLink to The Journal of Clinical Investigation
. 1988 Oct;82(4):1301–1305. doi: 10.1172/JCI113730

Sympathetic nerve discharge is coupled to muscle cell pH during exercise in humans.

R G Victor 1, L A Bertocci 1, S L Pryor 1, R L Nunnally 1
PMCID: PMC442683  PMID: 3170747

Abstract

We used phosphorus nuclear magnetic resonance spectroscopy (31P-NMR) to probe the cellular events in contracting muscle that initiate the reflex stimulation of sympathetic outflow during exercise. In conscious humans, we performed 31P-NMR on exercising forearm muscle and simultaneously recorded muscle sympathetic nerve activity (MSNA) with microelectrodes in the peroneal nerve to determine if the activation of MSNA is coupled to muscle pH, an index of glycolysis, or to the concentrations (II) of inorganic phosphate (Pi) and adenosine diphosphate (ADP) which are modulators of mitochondrial respiration. During both static and rhythmic handgrip, the onset of sympathetic activation in resting muscle coincided with the development of cellular acidification in active muscle. Furthermore, increases in MSNA were correlated closely with decreases in intracellular pH but dissociated from changes in phosphocreatine [( PCr]), [Pi], and [ADP]. The principal new conclusion is that activation of muscle sympathetic outflow during exercise in humans is coupled to the cellular accumulation of protons in contracting muscle.

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Selected References

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