z-logo
open-access-imgOpen Access
Mechanisms underlying the postexercise baroreceptor‐mediated suppression of heat loss
Author(s) -
McGinn Ryan,
Paull Gabrielle,
Meade Robert D.,
Fujii Naoto,
Kenny Glen P.
Publication year - 2014
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12168
Subject(s) - baroreceptor , microdialysis , theophylline , bretylium , chemistry , anesthesia , mean arterial pressure , medicine , endocrinology , heart rate , blood pressure , receptor , adrenergic , central nervous system
Reports indicate that postexercise heat loss is modulated by baroreceptor input; however, the mechanisms remain unknown. We examined the time‐dependent involvement of adenosine receptors, noradrenergic transmitters, and nitric oxide ( NO ) in modulating baroreceptor‐mediated changes in postexercise heat loss. Eight males performed two 15‐min cycling bouts (85% VO 2max ) each followed by a 45‐min recovery in the heat (35°C). Lower body positive ( LBPP ), negative ( LBNP ), or no (Control) pressure were applied in three separate sessions during the final 30‐min of each recovery. Four microdialysis fibres in the forearm skin were perfused with: (1) lactated Ringer's (Ringer's); (2) 4 mmol·L −1 Theophylline (inhibits adenosine receptors); (3) 10 mmol·L −1 Bretylium (inhibits noradrenergic transmitter release); or (4) 10 mmol·L −1 l ‐ NAME (inhibits NO synthase). We measured cutaneous vascular conductance ( CVC ; percentage of maximum) calculated as perfusion units divided by mean arterial pressure, and local sweat rate. Compared to Control, LBPP did not influence CVC at l ‐ NAME , Theophylline or Bretylium during either recovery ( P  >   0.07); however, CVC at Ringer's was increased by ~5‐8% throughout 30 min of LBPP during Recovery 1 (all P  <   0.02). In fact, CVC at Ringer's was similar to Theophylline and Bretylium during LBPP . Conversely, LBNP reduced CVC at all microdialysis sites by ~7–10% in the last 15 min of Recovery 2 (all P  <   0.05). Local sweat rate was similar at all treatment sites as a function of pressure condition ( P  >   0.10). We show that baroreceptor input modulates postexercise CVC to some extent via adenosine receptors, noradrenergic vasoconstriction, and NO whereas no influence was observed for postexercise sweating.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.
Having issues? You can contact us here