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This Article Full Text Full Text (PDF) All Versions of this Article: 550/2/575    most recent 2003.040147v1 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 Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Studinger, P. Articles by Kollai, M. Search for Related Content PubMed PubMed Citation Articles by Studinger, P. Articles by Kollai, M.

Static and dynamic changes in carotid artery diameter in humans during and after strenuous exercise

Péter Studinger, Zsuzsanna Lénárd, Zsuzsanna Kováts, László Kocsis and Mark Kollai

Arterial baroreflex function is altered by dynamic exercise, but it is not clear to what extent baroreflex changes are due to altered transduction of pressure into deformation of the barosensory vessel wall. In this study we measured changes in mean common carotid artery diameter and the pulsatile pressure : diameter ratio (PDR) during and after dynamic exercise. Ten young, healthy subjects performed a graded exercise protocol to exhaustion on a bicycle ergometer. Carotid dimensions were measured with an ultrasound wall-tracking system; central arterial pressure was measured with the use of radial tonometry and the generalized transfer function; baroreflex sensitivity (BRS) was assessed in the post-exercise period by spectral analysis and the sequence method. Data are given as means ± S.E.M. Mean carotid artery diameter increased during exercise as compared with control levels, but carotid distension amplitude did not change. PDR was reduced from 27.3 ± 2.7 to 13.7 ± 1.0 µm mmHg^-1. Immediately after stopping exercise, the carotid artery constricted and PDR remained reduced. At 60 min post-exercise, the carotid artery dilated and the PDR increased above control levels (33.9 ± 1.4 µm mmHg^-1). The post-exercise changes in PDR were closely paralleled by those in BRS (0.74 r 0.83, P < 0.05). These changes in mean carotid diameter and PDR suggest that the mean baroreceptor activity level increases during exercise, with reduced dynamic sensitivity; at the end of exercise baroreceptors are suddenly unloaded, then at 1 h post-exercise, baroreceptor activity increases again with increasing dynamic sensitivity. The close correlation between PDR and BRS observed at post-exercise underlies the significance of mechanical factors in arterial baroreflex control.