Contribution of the Potassium Channels K1.3 and K3.1 to Smooth Muscle Cell Proliferation in Growing Collateral Arteries.

Collateral artery growth (arteriogenesis) involves the proliferation of vascular endothelial cells (ECs) and smooth muscle cells (SMCs). Whereas the proliferation of ECs is directly related to shear stress, the driving force for arteriogenesis, little is known about the mechanisms of SMC proliferation. Here we investigated the functional relevance of the potassium channels K1.3 and K3.1 for SMC proliferation in arteriogenesis. Employing a murine hindlimb model of arteriogenesis, we found that blocking K1.3 with PAP-1 or K3.1. with TRAM-34, both interfered with reperfusion recovery after femoral artery ligation as shown by Laser-Doppler Imaging. However, only treatment with PAP-1 resulted in a reduced SMC proliferation. qRT-PCR results revealed an impaired downregulation of α smooth muscle-actin (αSM-actin) and a repressed expression of fibroblast growth factor receptor 1 () and platelet derived growth factor receptor b () in growing collaterals in vivo and in primary murine arterial SMCs in vitro under K1.3. blockade, but not when K3.1 was blocked. Moreover, treatment with PAP-1 impaired the mRNA expression of the cell cycle regulator early growth response-1 () in vivo and in vitro. Together, these data indicate that K1.3 but not K3.1 contributes to SMC proliferation in arteriogenesis.