AGI November 40/5

Xu, Chuanli, Yanjie Lu, Guanghua Tang, and Rui Wang. Expression of voltage-dependent K1 channel genes in mesenteric artery smooth muscle cells. Am. J. Physiol. 277 (Gastrointest. Liver Physiol. 40): G1055–G1063, 1999.— Molecular basis of native voltage-dependent K1 (Kv) channels in smooth muscle cells (SMCs) from rat mesenteric arteries was investigated. The whole cell patch-clamp study revealed that a 4-aminopyridine-sensitive delayed rectifier K1 current (IK) was the predominant K1 conductance in these cells. A systematic screening of the expression of 18 Kv channel genes using RT-PCR technique showed that six IK-encoding genes (Kv1.2, Kv1.3, Kv1.5, Kv2.1, Kv2.2, and Kv3.2) were expressed in mesenteric artery. Although no transient outward Kv currents (IA) were recorded in the studied SMCs, transcripts of multiple IA-encoding genes, including Kv1.4, Kv3.3, Kv3.4, Kv4.1, Kv4.2, and Kv4.3 as well as IA-facilitating Kv b-subunits (Kvb1, Kvb2, and Kvb3), were detected in mesenteric arteries. Western blot analysis demonstrated that four IK-related Kv channel proteins (Kv1.2, Kv1.3, Kv1.5, and Kv2.1) were detected in mesenteric artery tissues. The presence of Kv1.2, Kv1.3, Kv1.5, and Kv2.1 channel proteins in isolated SMCs was further confirmed by immunocytochemistry study. Our results suggest that the native IK in rat mesenteric artery SMCs might be generated by heteromultimerization of Kv genes.