Kinetic Differences between Ca$^{2+}$-dependent K$^{+}$ Channels in Smooth Muscle Cells Isolated from Normal and Atherosclerotic Human Aorta

The properties of large conductance Ca$^{2+}$-dependent K$^{+}$ channels in smooth muscle cells (SMC) isolated from normal and atherosclerotic human aorta were studied using the patch-clamp technique. It was shown that SMC from normal human aorta possess a homogeneous population of normal Ca$^{2+}$-dependent K$^{+}$ channels. In atherosclerotic aorta two kinetically different types of these channels could be distinguished: along with normal \`long' (L)-type channels there appeared channels of \`short' (s)-type. Under similar conditions s-type channels had about a four times shorter mean open time. About five times higher [Ca$^{2+}$]$_{\text{in}}$ was necessary for s-type channels to reach the probability of the channels being open equal to L-type channels. No differences in conductance and voltage dependency were found between the two channel types. Channels of the s-type resembled those previously described in SMC isolated from foetal human aorta. Thus, it can be suggested that during the development of atherosclerosis a population of SMC with s-type Ca$^{2+}$-dependent K$^{+}$ channels appears in human aorta.