ROLE OF ENDOTHELIN-1 IN THE FAILURE OF CEREBRAL-CIRCULATION AFTER COMPLETE GLOBAL CEREBRAL-ISCHEMIA

The role of endothelin-1 (ET-1) in the failure of cerebral circulation after cardiac arrest is unknown. We evaluated the effect of complete global cerebral ischemia that was induced on the plasma ET-1 concentra tion in 5 dogs, by occluding the ascending aorta and caval veins for 1 5 min. A fiberoptic catheter was inserted into the sagittal sinus for the continuous monitoring of venous oxygen saturation. Blood samples w ere collected before and at 0.5, 1, 2, 4, and 6 h after the ischemic i nsult. The ET-1 concentration in the sagittal sinus and abdominal aort a was assayed. Complete global cerebral ischemia resulted in a signifi cant 3-fold increase in the sagittal sinus concentration of ET-1 (P < 0.01) that was associated with a significant decrease in the sagittal sinus venous oxygen saturation (P < 0.01); the arterial ET-1 concentra tion remained unchanged. The difference between arterial and venous ET -1 concentrations during the hypoperfusion phase subsequent to the isc hemic insult may result from an increased secretion of ET-1 by the cer ebrovasculature and a decrease in the clearance of ET-1 in the cerebra l circulation. The result suggests that ET-1 may contribute to the fai lure of cerebral circulation after cardiac arrest.