Central angiotensin AT2‐receptor blockade affects thermoregulation and running performance in rats (1104.16)

Abstract

The aim of the study was to verify the effect of central angiotensin II AT2 receptor blockade in thermoregulatory responses during exercise in rats. Internal (Tb) and skin tail (Ttail) temperatures were measured in Wistar rats while they were running until fatigue (18 m.min‐¹, 5% inclination) after intracerebroventricular injection of 2µL of PD 123319 (PD; AT2 angiotensin II receptor antagonist; 10 µg) or 0.15 M NaCl (SAL) (n=7/each). Total time of exercise until fatigue (TTE) and workload (W) were determined. Rats treated with PD had an increase of 17% and 20% in TTE and W, respectively, in comparison with SAL animals (p<0.05). During exercise, Tb enhanced in both group, however, no difference was seen between treatments. On the other hand, following the first 15 minutes of exercise, Ttail variation was superior in PD rats until fatigue (3.1 ± 1,5 °C Sal vs. 4.9 ± 1,2 °C PD, p<0.05). Moreover, the increased Ttail at fatigue shown by PD‐rats directly correlated with their enhanced TTE (r = 0.82, P < 0.01). The data shows that AT2 receptor blockade improves heat balance during exercise due to better ability to dissipate heat, which contributes to enhanced exercise performance. Grant Funding Source: FAPEMIG, CNPq and CAPES