Abstract
[Introduction] Despite accumulated numerous knowledge as to human muscle sympathetic nerve activity (SNA) measured by microneurography, whether sympathetic tone of muscle SNA parallels that of other SNAs, in particular renal and cardiac SNAs, remains unknown. [Methods] In urethane (250mg/ml) and α-chloralose anesthetized, vagotomized and aortic-denervated rabbits, we recorded muscle SNA from tibial nerve using microneurography, together with renal and cardiac SNAs. We stepwise changed sympathetic tone of each SNA by isolating the carotid sinuses and increasing intra-carotid sinus pressure (CSP) stepwise from 40 to 160 mmHg with an increase of 20-mmHg. Each pressure step was maintained for 60 s. We averaged each SNA over 1 minute, and calculated the correlation coefficient (r) between muscle and renal or cardiac SNA. Additionally, we compared static characteristics of baroreflex control of SNA between them. [Results] Muscle SNA averaged over 1 minute correlated strongly both with renal (r2 =0.96) and cardiac SNAs (r2 =0.96). [Conclusion] Sympathetic tone of muscle SNA parallels that of renal and cardiac SNAs in response to baroreceptor pressure change. [Jpn J Physiol 54 Suppl:S202 (2004)]
