Expression of voltage-dependent K+ channel genes in mesenteric artery smooth muscle cells

Molecular basis of native voltage-dependent K+ (Kv) channels in smooth musc le cells (SMCs) from rat mesenteric arteries was investigated. The whole ce ll patch-clamp study revealed that a 4-aminopyridine-sensitive delayed rect ifier K+ current (I-K) was the predominant K+ conductance in these cells. A systematic screening of the expression of 18 Kv channel genes using RT-PCR technique showed that six I-K-encoding genes (Kv1.2, Kv1.3, Kv1.5, Kv2.1, Kv2.2, and Kv3.2) were expressed in mesenteric artery. Although no transien t outward Kv currents (I-A) were recorded in the studied SMCs, transcripts of multiple I-A-encoding genes, including Kv1.4, Kv3.3, Kv3.4, Kv4.1, Kv4.2 , and Kv4.3 as well as I-A-facilitating Kv beta-subunits (Kv beta 1, Kv bet a 2, and Kv beta 3), were detected in mesenteric arteries. Western blot ana lysis demonstrated that four I-K-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 fu rther confirmed by immunocytochemistry study. Our results suggest that the native I-K in rat mesenteric artery SMCs might be generated by heteromultim erization of Kv genes.