In Vitro Model of Brain Trauma: in Isolated Basilar Artery Hemolysed Blood‐induced Constriction is Inhibited by Calcium Channel Blocker and Increased CO 2

Abstract

Objective. Cerebrovascular hemorrhage (stroke, trauma) is followed by increased vascular resistance. We hypothesized that extraluminal hemolysed blood (HeBl) increases the tone and affects vasomotor responses of isolated cerebral arteries. Methods. Rat basilar arteries (BA) were isolated and placed in a vessel chamber. In control, in the presence of and after washout of HeBl vasomotor responses of vessels were studied in responses to acetylcholine (ACh), sodium-nitroprusside (SNP), nifedipine (Nif) and CO2, then the passive diameter of vessels (PD) was determined in Ca2+-free Krebs solution. Results. The diameters of BA were 277,5±11,5 µm, whereas their PDs were 392±8,1 µm. HeBl reduced the diameters of BA (to 163,8±11,1 µm; 59,13±4% of AD) and increased intracellular Ca2+. After HeBl washout, the diameters of BA returned the control: 284±9 µm. In control, ACh, SNP, Nif and CO2 elicited substantial dilations (20±2%, 26±2%, 32±3% and 26±2%). In contrast, in the presence of HeBl dilation to ACh and SNP decreased, but not to Nif and CO2 (7±1%, 12±2%, 28±3% and 30±2%). After HeBl washout NO-dependent dilations were still significantly reduced compared to control (ACh: 6±1%, SNP: 14±2%). Conclusion In isolated cerebral arteries hemolysed blood elicits substantial constriction and inhibits NO-dependent dilations, but does not affect Ca-channel blocker and CO2-induced dilations. Support: Hungarian Scientific Research Fund (OTKA) 108444, MHT2013/14).