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: 93/9/1044    most recent expphysiol.2008.042234v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Drew, R. C. Articles by White, M. J. PubMed PubMed Citation Articles by Drew, R. C. Articles by White, M. J. Related Collections Cardiovascular control

¹ School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

We examined the effects of muscle mechanoreflex stimulation by passive calf muscle stretch, at rest and during concurrent muscle metaboreflex activation, on carotid baroreflex (CBR) sensitivity. Twelve subjects either performed 1.5 min one-legged isometric plantarflexion at 50% maximal voluntary contraction with their right or left calf [two ischaemic exercise (IE) trials, IER and IEL] or rested for 1.5 min [two ischaemic control (IC) trials, ICR and ICL]. Following exercise, blood pressure elevation was partly maintained by local circulatory occlusion (CO). 3.5 min of CO was followed by 3 min of CO with passive stretch (STR-CO) of the right calf in all trials. Carotid baroreflex function was assessed using rapid pulses of neck pressure from +40 to –80 mmHg. In all IC trials, stretch did not alter maximal gain of carotid–cardiac (CBR–HR) and carotid–vasomotor (CBR–MAP) baroreflex function curves. The CBR–HR curve was reset without change in maximal gain during STR-CO in the IEL trial. However, during the IER trial maximal gain of the CBR–HR curve was smaller than in all other trials (–0.34 ± 0.04 beats min^–1 mmHg^–1 in IER versus –0.76 ± 0.20, –0.94 ± 0.14 and –0.66 ± 0.18 beats min^–1 mmHg^–1 in ICR, IEL and ICL, respectively), and significantly smaller than in IEL (P < 0.05). The CBR–MAP curves were reset from CO values by STR-CO in the IEL and IER trials with no changes in maximal gain. These results suggest that metabolite sensitization of stretch-sensitive muscle mechanoreceptive afferents modulates baroreflex control of heart rate but not blood pressure.

(Received 31 January 2008; accepted after revision 24 April 2008; first published online 9 May 2008)
Corresponding author R. C. Drew: School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. Email: rxd117{at}bham.ac.uk