AUTHOR=Li Jianhua , Gao Zhaohui , Lu Jian , Xing Jihong 

TITLE=Exaggerated Pressor Response in Relation to Attenuated Muscle Temperature Response during Contraction in Ischemic Heart Failure

JOURNAL=Frontiers in Physiology

VOLUME=3

YEAR=2012

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2012.00443

DOI=10.3389/fphys.2012.00443

ISSN=1664-042X

ABSTRACT=<p>It is known that muscle temperature (<italic>T</italic><sub>m</sub>) increases with exercise. The purpose of this study was to examine if contraction-induced increase in <italic>T</italic><sub>m</sub> was altered in rats with heart failure (HF) induced by chronic myocardial infraction (MI) as compared with healthy control animals. A temperature probe was inserted in the triceps surae muscle to continuously measure <italic>T</italic><sub>m</sub> throughout experiments. Static muscle contraction was induced by electrical stimulation of the sciatic nerve for 1 min. As baseline <italic>T</italic><sub>m</sub> was 34°C, contraction increased temperature by 1.6 ± 0.18°C in nine health control rats and by 1.0 ± 0.15°C in 10 MI rats (<italic>P</italic> &lt; 0.05 vs. control). Note that there were no differences in developed muscle tension and muscle weight between the two groups. In addition, muscle contraction increased mean arterial pressure by 23 ± 3 mmHg in control rats and by 31 ± 3 mmHg in MI rats (<italic>P</italic> &lt; 0.05 vs. control). A regression analysis further shows that there is an inverse liner relationship between the pressor response and static contraction-induced increase in <italic>T</italic><sub>m</sub>. Our data suggest that <italic>T</italic><sub>m</sub> increase evoked by contraction is impaired in MI rats. The abnormal alteration in <italic>T</italic><sub>m</sub> likely modifies the reflex cardiovascular responses in MI via mechanisms of temperature-sensitive receptors on muscle afferent nerves.</p>