Cardiopulmonary reflex and blood pressure response after swimming and treadmill exercise in hypertensive rats.

Abstract

Cardiopulmonary sensitivity was evaluated after exercise training through swimming and running in spontaneously hypertensive rats (SHR) that were divided into three groups: (a) run exercise; (b) swim exercise; and (c) sedentary. For 8 wks, the run exercise was performed on a treadmill while the swim exercise was performed by swimming. Cardiopulmonary reflex was evaluated by chemical and mechanical pathways through the injections of phenylbiguanide (PBG) (5.0 mg·kg-1) and volume expansion with isotonic saline (0.75% of body weight), respectively. Both types of exercise training decreased systolic blood pressure (SBP) compared to the sedentary group. The swim trained group reduced SBP faster than the run trained group. The sensitivity of the chemically activated endings of the cardiopulmonary reflex was increased in both exercise-trained groups for hypotensive response. The exercise training groups had higher levels of urine output after acute volume expansion. The production of urine showed that swimming and treadmill training were more efficient than the sedentary group. These results indicate that: (a) exercise improved cardiopulmonary reflex sensitivity; and (b) swim training led to a faster SBP reduction and a more sensitive reflex response to pressure stimuli.