CARDIOVASCULAR CHANGES DURING FOCAL CEREBRAL-ISCHEMIA IN RATS

Background and Purpose: Recent studies have suggested that cerebral in farction influences autonomic activity and way contribute to sudden de ath. The goal of this study was to examine effects of focal cerebral i nfarction on mean arterial pressure and heart rate. Methods: Halothane -anesthetized rats were assigned to two groups: stroke (n = 10), in wh ich the middle cerebral artery or an adjacent vessel was embolized wit h a silicone cylinder, and sham (n = 8), in which rats were sham embol ized (saline). Arterial pressure and heart rate were measured for 90 m inutes and again 24 hours after vascular occlusion. A change in electr oencephalographic amplitude of -45% after embolization was used to det ermine if a significant degree of infarction was present. Results: Vas cular occlusion produced a significant increase in mean arterial press ure at 10, 60, and 90 minutes (p<0.05). Changes in heart rate were sig nificantly greater (p<0.05) than in sham-treated rats at 10 and 30 min utes after embolization. In contrast, mean arterial pressure and heart rate measured 24 hours after embolization were similar in both groups . Anatomic analysis of the infarcted areas demonstrated that either in sular cortex or amygdala was affected in all embolized rats. Conclusio ns: This study indicates that cerebral infarction produces a transient elevation of mean arterial pressure and heart rate. However, within 2 4 hours both parameters returned to preinfarcted levels. Our findings are consistent with clinical reports that indicate that mean arterial pressure and heart rate of stroke patients are similar to those of oth er groups when they are admitted to the hospital, although other cardi ovascular parameters are greatly altered.