Abstract

The effects of intracerebroventricular (icv) administration of a corticotropin-releasing factor (CRF) receptor antagonist, alpha-helical CFR9-41, on systematic and regional hemodynamic adjustements to exercise were studied in conscious rats. On consecutive days, rats received saline icv, alpha-helical CRF9-41 ivc, and no treatment 30 min before treadmill exercise (TMX). Increases in heart rate (HR) and mean arterial pressure (MAP) in response to TMX (16.1-28.6 m/min) were similar after icv administration of saline or no treatment. In rats receiving saline icv or no treatment, estimated vascular resistance increased in the mesentric and renal regions and declined in the iliac (hindlimb) region. After icv administration of alpha-helical CRF9-41, HR and MAP responses during TMX were significantly attenuated. In addition, TMX-induced elevations of estimated mesentric vascular resistance and iliac blood flow velocity were blunted after CRF receptor blockade. These altered cardiovascular and hemodynamic responses were ultimately reflected in the animals compromised ability to run. The results suggest that the central nervous system actions of endogenous CRF are necessary for the full expression of the cardiovascular adjustments to TMX in the conscious rat. Verf.-Referat