Role of the cAMP/PKA pathway in the regulation of slow delayed rectifier K+ (IKs) current. (A, B) Representative experiments demonstrating the effects of ISO in the presence of Rp-8-Br-cAMP (A) and 8-Br-cAMP (B). In (C), left-hand column of each pair shows IKs tail current amplitude measured in control (no drug, n= 11), and after internal application of Rp-8-Br-cAMP (100 µM, n= 5) and 8-Br-cAMP (250 µM, n= 5). Right-hand column of each pair indicates IKs tails obtained following superfusion with 100 nM ISO. Data are means ± SEM. *Indicates significant (P < 0.05) differences from the control (no drug)IKs amplitude determined using unpaired t-test. +Denotes ISO-induced differences from the respective pre-ISO values determined using paired t-test. ISO, isoprenaline; PKA, protein kinase.