SWIM TRAINING ALTERS SYMPATHOADRENAL AND ENDOCRINE RESPONSES TO HEMORRHAGE IN BORDERLINE HYPERTENSIVE RATS

Swim training alters cardiovascular, sympathoadrenal, and endocrine re sponses to hemorrhage in borderline hypertensive rats (BHR). The effec ts of 10, 20, and 30% blood volume hemorrhages on cardiovascular, symp athoadrenal, and endocrine function in swim-trained (T; 2 h/day, 5 day /wk for 10-12 wk) and age-matched, untrained, sedentary, control (UT) borderline hypertensive rats (BHR) were assessed. Heart rate (HR) in U T BHR was significantly greater during the baseline (rest) period than T BHR. HR increased slightly from baseline in both groups after 10% h emorrhage but was significantly decreased in both groups after 20 and 30% hemorrhages. The decrease was eliminated by atropine (1 mg/kg iv). Systolic (SEP) and diastolic (DBP) blood pressures decreased signific antly after 20 and 30% hemorrhages in both T and UT BHR but were not d ifferent between the groups at these times. Plasma norepinephrine leve ls were significantly increased above baseline after 20 and 30% hemorr hages in UT BHR and were significantly greater in UT BHR than T BHR af ter 30% hemorrhage. Plasma glucose levels increased significantly afte r 30% hemorrhage in both groups but were significantly greater in UT B HR than T BHR. Both plasma norepinephrine and plasma epinephrine level s showed strong positive correlations with plasma glucose. After 20 an d 30% hemorrhages, plasma insulin levels were unchanged in T BHR but w ere significantly decreased in UT BHR. Plasma insulin levels were sign ificantly less in UT than T BHR after 30% hemorrhage. These results su ggest that swim training alters the effect that; hemorrhage exerts on endocrine and sympathoadrenal function in BHR. Moreover, fluid and ele ctrolyte conservation in T BHR appears to be the result of less glucos e mobilization and hence may conserve energy stores in response to hem orrhage.