HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 293/4/H2335    most recent 00469.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Koba, S. Articles by Li, J. Search for Related Content PubMed PubMed Citation Articles by Koba, S. Articles by Li, J.

Differential sympathetic outflow elicited by active muscle in rats

Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania

Submitted 17 April 2007 ; accepted in final form 11 June 2007

The present study was undertaken to test the hypothesis that activation of the muscle reflex elicits less sympathetic activation in skeletal muscle than in internal organs. In decerebrate rats, we examined renal and lumbar (mainly innervating hindlimb blood vessels) sympathetic nerve activities (RSNA and LSNA, respectively) during 1 min of 1) repetitive (1- to 4-s stimulation-to-relaxation) contraction of the triceps surae muscle, 2) repetitive tendon stretch, and 3) repetitive contraction with hindlimb circulatory occlusion. During these interventions, RSNA and LSNA responded synchronously as tension developed. The increase was greater in RSNA than in LSNA [+51 ± 14 vs. +24 ± 5% (P < 0.05) with contraction, +46 ± 8 vs. +17 ± 4% (P < 0.05) with stretch, +76 ± 20 vs. 39 ± 7% (P < 0.05) with contraction during occlusion] during all three interventions: repetitive contraction (n = 10, +508 ± 48 g tension from baseline), tendon stretch (n = 12, +454 ± 34 g), and contraction during occlusion (n = 9, +473 ± 33 g). Additionally, hindlimb circulatory occlusion significantly enhanced RSNA and LSNA responses to contraction. These data demonstrate that RSNA responses to muscle contraction and stretch are greater than LSNA responses. We suggest that activation of the muscle afferents induces the differential sympathetic outflow that is directed toward the kidney as opposed to the limbs. This differential outflow contributes to the distribution of cardiac output observed during exercise. We further suggest that as exercise proceeds, muscle metabolites produced in contracting muscle sensitize muscle afferents and enhance sympathetic drive to limbs and renal beds.

sympathetic nervous system; exercise; muscle metabolites; contraction; stretch

This article has been cited by other articles:

				S. Koba, Z. Gao, and L. I. Sinoway Oxidative stress and the muscle reflex in heart failure J. Physiol., November 1, 2009; 587(21): 5227 - 5237. [Abstract] [Full Text] [PDF]

				H. Tsuchimochi, S. G. Hayes, J. L. McCord, and M. P. Kaufman Both central command and exercise pressor reflex activate cardiac sympathetic nerve activity in decerebrate cats Am J Physiol Heart Circ Physiol, April 1, 2009; 296(4): H1157 - H1163. [Abstract] [Full Text] [PDF]

				J. Xing, Z. Gao, J. Lu, L. I. Sinoway, and J. Li Femoral artery occlusion augments TRPV1-mediated sympathetic responsiveness Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1262 - H1269. [Abstract] [Full Text] [PDF]

				S. Koba, J. Xing, L. I. Sinoway, and J. Li Sympathetic nerve responses to muscle contraction and stretch in ischemic heart failure Am J Physiol Heart Circ Physiol, January 1, 2008; 294(1): H311 - H321. [Abstract] [Full Text] [PDF]