RETENTION OF CEREBROVASCULAR DILATION AFTER CORTICAL SPREADING DEPRESSION IN ANESTHETIZED RABBITS

Background and Purpose: We examined responses of rabbit pial arterioles to three different stimuli before and after induction of cortical spreading depression. Methods: In urethane-anesthetized rabbits equipped with a closed cranial window, we measured pial arteriolar diameter during baseline conditions, topical application of calcitonin gene-related peptide (CGRP), topical application of acetylcholine, and inhalation of 10% CO2 in air (arterial hypercapnia) before cortical spreading depression and 30, 60, and 120 minutes after cortical spreading depression. Cortical spreading depression was induced by localized application of a 5% KCl solution anterior to the arteriole being measured. Results: Average baseline diameter was approximately 90 mum. During cortical spreading depression, arteriolar diameter increased to a peak value that was 50+/-4% above baseline (n=32). Before cortical spreading depression, arteriolar diameter changed 47+/-7% (n=9) during hypercapnia, 17+/-3% (n=4) during 10(-9) mol/L CGRP, 42+/-10% (n=7) during 10(-7) mol/L CGRP, 29+/-6% (n=4) during 10(-6) mol/L acetylcholine, and 61+/-13% (n=6) during 10(-4) mol/L acetylcholine. Arteriolar responsiveness to any of these stimuli was not changed significantly by prior cortical spreading depression. Conclusions: Dilator capacity of pial arterioles is still intact in urethane-anesthetized rabbits after cortical spreading depression.