Fig. 5.

Comparison of BK single-channel function in FHH and FHH.1^BN rats before and after administration of the BK channel antagonist IBTX. BK single-channel currents recorded from inside-out patch-clamp of VSMCs obtained from FHH and FHH.1^BN congenic strain are shown. A: representative BK single-channel currents recorded from FHH and FHH.1^BN rats at +40 mV membrane potential and at 1 μM free calcium concentration in the bath in the presence and absence of IBTX. In the presence of IBTX, the NP_o plotted as a function of membrane voltage (mV), presented in B, is significantly lower in FHH rats compared with FHH.1^BN rats (n = 3–5 patches per data point). C: a summary graph that indicates that BK channel NP_o is reduced by 83% in FHH rats after administration of IBTX compared with a 54% fall in NP_o in FHH.1^BN rats at +40 mV membrane potential. Mean values ± SE are presented. *Significant difference from the corresponding value in FHH rats.