Studies in vitro suggest that the basilar artery has distinctive responses to endotheliumde pendent stimuli. Our first goal was to examine the effects of acetylcholine on diameter of the basilar artery in vivo. Because aggregating platelets may have important effects on cerebral arteries, our second goal was to examine the effects on the basilar artery of products that are released by platelets (thromboxane, serotonin, and adenosine 5′-diphosphate). Diameter of the basilar artery was measured through a cranial window in anesthetized rats (n=25). Baseline diameter of the basilar artery was 247±10 /μm mean± SEM. Topical application of acetylcholine at 106 and 10-5 M dilated the basilar artery by 13±2% and 19±2%, respectively. The thromboxane analogue U46619 at 10-5 and 10-7 M reduced the diameter of the basilar artery by 18±5% and 29±4%, respectively. At 10-8 and 10-7 M, serotonin had little effect on pial arterioles on the cerebrum but constricted the basilar artery by 18 ±2% and 29 ±4%, respectively. At 10-6 and 10-5M, adenosine 5′-diphosphate produced marked dilatation of pial arterioles on the cerebrum (9±2% and 20±3%, respectively) but had little effect on the basilar artery (increased diameter by 4±2% and 6±2%, respectively). Thus, in contrast to some studies of the basilar artery in vitro, acetylcholine produces dilatation of the basilar artery in vivo. Potent constrictor responses to thromboxane and serotonin, in combination with the minimal dilator effect of adenosine 5′-diphosphate, suggest that release of these products during platelet aggregation would favor constriction of the basilar artery.
- Basilar artery
ASJC Scopus subject areas
- Clinical Neurology
- Cardiology and Cardiovascular Medicine
- Advanced and Specialized Nursing