Human inward rectifier potassium channels in chronic and postoperative atrial fibrillation

We showed recently that the 825T allele of the G-protein beta 3-subunit C825T polymorphism is associated with large inward rectifier K(+) currents I(K1) but low acetylcholine-activated K(+) current I(K,ACh) amplitudes. During chronic atrial fibrillation (AF), I(K1) and I(K,ACh) current densities were increased when compared to sinus rhythm (SR). It is unknown whether chronic AF and G beta 3 gene status are independent contributors to atrial K(+) current activity. We measured I(K1) and I(K,ACh) in tissue from AF patients with different G beta 3 genotypes and assessed the relation between the I(K1) and I(K,ACh) amplitudes and the incidence of postoperative AF. We measured the amplitudes of I(K1) and I(K,ACh) in atrial myocytes from 26 patients with sinus rhythm (SR) and from 16 patients with chronic AF (>6 months). The K(+) currents were measured with standard patch-clamp techniques. The G beta 3 gene status of the patients was determined by PCR and restriction analysis. At -100 mV, the amplitude of I(K1) was larger in AF (10.9+/-1.0 pA/pF, n=49/16, cells/patients) than in SR (6.3+/-0.6 pA/pF, n=68/26, P