COMPARISON BAROREFLEX BETWEEN MALE AND FEMALE RATS: ROLE OF EXERCISE TRAINING

Abstract

The objective of this study was to compare arterial baroreflex control between males and females rats, as well as submitted to an aerobic exercise training (ET). Wistar rats (n=32) were divided into 4 groups: sedentary (SM) and trained (TM) males, and sedentary (SF) and trained (TF) females. Arterial pressure (AP) and heart rate (HR) signals were directly recorded. The baroreflex sensitivity (BRS) was evaluated by tachycardic (TR) and bradycardic (BR) responses induced by AP changes, and also by the spontaneous BRS (alpha index) obtained by spectral analysis. The AP was similar between studied groups. Trained groups presented resting bradycardia. The BR was similar between SM and SF groups; and it was higher in TM (vs.SM) and to SF (vs.TF). The TF presented reduced BR (vs.SM and SF). The TR was higher in SF, TF and TM groups (vs.SM). The alpha index was increased in SF rats when compared to SM rats (1.03±0.12 vs. 0.69±0.09 ms/mmHg). The ET induced a reduction in TF group (0.60±0.08 ms/mmHg vs. SF), reaching similar values compared to SM group. The TM group (1.07±0.13 ms/mmHg) presented higher alpha index (vs.SM). These results showed enhanced BRS in females than in male rats. The ET induced resting bradycardia in both gender, but the improvement in BRS was just observed in trained males. These findings indicate important differences in cardiovascular reflex control associated with gender.