HEMOLYSED BLOOD‐INDUCED VASOMOTOR DYSFUNTION IN ISOLATED RAT CEREBRAL ARTERIES

Abstract

The underlying vasoconstrictor mechanisms following hemorrhagic stroke have not yet been elucidated. We hypothesized that hemolysed blood induces vasomotor dysfunction in isolated cerebral arteries. The basilar artery (BA) from male rats were isolated, cannulated and placed in a pressure‐myograph organ chamber. The diameters of vessels were measured by videomicroscopy in the presence of physiological intraluminal pressure (80 mmHg) without intraluminal flow. The vasomotor function of the vessels was studied in response to hemolysed blood (HB). Dilatory function of vessels were obtained in control conditions, in the presence of HB and after washout of HB. The basal diameter of BA was 264±7,5 μm, whereas the passive diameter was 404±10 μm, indicating that a substantial myogenic tone developed. HB reduced the basal diameter of BA (to 204±13 μm, 77±4% of AD). After washing out of HB, the diameter of BA was 284±9 μm. In control ACh, SNP and nifedipine elicited substantial dilations (16±2%, 23±3% and 31±2%) of cerebral arteries. In contrast, in the presence of HB dilations to ACh, SNP and nifedipine (12±2%, 16±2%, 21±2%) were significantly decreased. In conclusion, the present findings suggest that hemolysed blood increases the myogenic tone and inhibits both endothelium‐dependent and ‐independent dilator mechanisms of cerebral arteries.