Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC117
Role of Kv1.3 channels in the proliferation of human vascular smooth muscle cells
C. Ruiz-McDavitt1, E. Miguel-Velado1, S. Tajada1, P. Cidad1, M. Pérez-García1, J. López-López1
Vascular smooth-muscle cells (VSMCs) contribute significantly to occlusive vascular diseases by virtue of its ability to switch from a contractile phenotype to a cell that migrates and proliferates narrowing the vessel lumen. An important element of this phenotypic modulation is a switch in ion transport systems. Our previous work has explored this aspect in murine VSMCs from femoral arteries. We identified two genes, Kv1.3 and Kvβ2, that were up-regulated in proliferation. Functional studies demonstrated that the increased Kv1.3 currents in these cells were an essential component of their migratory and proliferative phenotype. In this study, we explored if the association between the phenotypic switch and the upregulation of Kv1.3 channels is conserved in human VSMCs from different vascular beds. We had access to uterine, coronary and renal arteries and saphenous veins from donors, through the Human Collection of Vascular Samples (COLMAH-HERACLES). All the protocols were approved by the Human Investigation Ethics Committees of the participant Hospitals, and conform to the principles outlined in the Declaration of Helsinki. The pieces were cleaned of endothelial and connective tissues and used directly or explanted to obtain cultured VSMCs. The expression levels of Kv1.3 and Kvβ2 mRNA was determined by real-time qPCR with Taqman® probes in both cultured and contractile VSMCs from the different samples. Protein expression levels were analyzed by western blot with specific antibodies. In addition, the functional expression of Kv1.3 channels was explored with patch-clamp techniques, quantifying the effect of selective Kv1.3 blockers (PAP-1 and Margatoxin) on the total outward K+ currents. Finally, the contribution of Kv1.3 channels to VSMCs proliferation was determined by exploring the effect of these selective blockers on the rate of BrdU incorporation to VSMCs in culture. Our results show that Kv1.3 and Kvβ2 contribute to the phenotypic switch of VSMCs in all the vascular beds studied. We observed that Kv1.3 mRNA becomes the predominant Kv1 message expressed in proliferating VSMCs, a switch that parallels the changes in Kv1.3 protein expression. Moreover, in all the vascular beds the selective blockade of Kv1.3 channel decreases the rate of cell proliferation without causing a significant increase in apoptotic cell death.We conclude that the functional expression of Kv1.3 channels in proliferating VSMCs is a common feature of different human vascular beds, so that new therapeutical approaches using selective blockers of Kv1.3 channels could represent an advantageous strategy to prevent unwanted remodeling.
Where applicable, experiments conform with Society ethical requirements