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

Abstract

It is known that muscle temperature (Tm) increases with exercise. The purpose of this study was to examine if contraction-induced increase in Tm 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 Tm throughout experiments. Static muscle contraction was induced by electrical stimulation of the sciatic nerve for 1 min. As baseline Tm 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 (P < 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 (P < 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 Tm. Our data suggest that Tm increase evoked by contraction is impaired in MI rats. The abnormal alteration in Tm likely modifies the reflex cardiovascular responses in MI via mechanisms of temperature-sensitive receptors on muscle afferent nerves.

Purinergic P2X Receptors and Heightened Exercise Pressor Reflex in Peripheral Artery Disease

“…In addition, our data suggest that muscle temperature response to static contraction is attenuated in rats with conditions of tissue ischemia induce by chronic heart failure as compared with control animals [66]. The results may have important implications for understanding cardiovascular responses to exercise where muscle temperature rises.…”

Neural control of the circulation during exercise in health and disease

“…For example, EPR dysfunction has been shown to contribute to the augmented exercise-induced sympatho-excitation in heart failure and hypertension. In this research topic, for the first time, alterations in muscle temperature are considered as a possible contributing factor to the exaggerated EPR activity in heart failure (Li et al, 2012). More importantly, Li and Xing (2012) extend the list of diseases with impairments in EPR function to include peripheral arterial disease.…”