Fig. 9.

Comparison of the myogenic response in middle cerebral arteries (MCAs) of FHH and FHH.1^BN rats before and after application of the BK channel antagonist IBTX. A: pressure-diameter relationships that were obtained from MCAs isolated from FHH and FHH.1^BN congenic rat strain in the presence and absence of calcium and before and after addition of IBTX to the bath. MCAs isolated from FHH rats exhibit an impaired myogenic response relative to FHH.1^BN congenic rats, and the response was restored after administration of IBTX. In contrast, IBTX did not alter the myogenic response of MCAs isolated from FHH.1^BN congenic strain. B: summary graph presenting the percent active tone generated in the MCAs at 120 mmHg before and after IBTX application in MCAs isolated from FHH and FHH.1^BN rats. Mean values ± SE are presented. *Significant difference from the corresponding values presented in FHH rats before administration of IBTX.