CARDIOVASCULAR-RESPONSE TO STRESS AFTER MIDDLE CEREBRAL-ARTERY OCCLUSION IN RATS

Previously, we have shown cardiovascular and autonomic disturbances in male Wistar rats following middle cerebral artery occlusion (MCAO). U sing this model, neurochemical changes, that were maximal at 3-5 days and subsiding by day 10, were observed unilaterally in the insular cor tex and amygdala. The amygdalar neurochemical changes may be related t o the stroke-induced cardiovascular disturbances, since the amygdala i s critical in mediating the cardiovascular responses to stress. We exa mined the cardiovascular responses to intermittent and continuous nois e and air-jet stimulation in male Wistar rats on days 2-10 after right -sided MCAO or sham MCAO. Compared to the sham MCAO rats, intermittent noise elicited significant tachycardiac responses on days 5 and 7 aft er stroke. Air-jet stimulation also elicited a significant tachycardic response on day 5, whereas continuous noise produced significant tach ycardiac and presser responses at days 5 and 7, respectively, in the M CAO rats compared to the control rats. Analyses on the heart rate vari ability using fast Fourier transformation revealed significant increas es in the normalized mid-frequency spectral power on day 7 for intermi ttent noise and air-jet stimulation, suggesting increases in the sympa thetic activity. These results indicate a time-course of exaggerated c ardiovascular responses to stress and suggest a state of susceptibilit y to cardiac perturbations in rats following stroke.