Perivascular blood induces substantial constrictions of isolated basilar artery, which can be reversed by high pCO2

Abstract

The vasoconstrictor mechanisms in acute intracerebral hemorrhage have not been fully clarified. We hypothesized that perivascular hemolysed blood (HB) has substantial effects on the tone and vasomotor responses of isolated cerebral arteries.Basilar artery (BA) from male rats was isolated and placed in a pressure‐myograph chamber. The diameters of vessels were measured by videomicroscopy. After administration of HB the vasomotor function of vessels was studied in responses to acetylcholine (Ach), sodium‐nitroprusside (SNP), nifedipine (Nife) and CO2, which were obtained in control condition, in the presence of HB, and after washout of HB.The active diameters of BA were 277±11 μm. HB reduced the basal diameters of BA (to 164±11 μm; 59±4% of AD). After washing out of HB, the active diameters of BA reached the control level: 284±9 μm. In control, Ach, SNP, Nife and CO2 elicited substantial dilations in cerebral arteries (20±2%, 26±2%, 32±3% and 26±2%). In contrast, HB decreased the dilation to ACh, SNP, but not to nifedipin and CO2 (7±1%, 12±2%, 28±3% and 30±2%). After washout of HB NO‐dependent dilations were significantly reduced compared to control (ACh: 6±1%, SNP:14±2%).Findings of the present study show that extraluminal HB elicits substantial constrictions and inhibits NO‐dependent dilations, but does not affect Ca‐channel blocker and CO2‐induced dilations.