Kinetic differences between C a2+-dependent K + channels in smooth muscle cells isolated from norm al and atherosclerotic hum an aorta

T he properties of large conductance C a2+-dependent K + channels in smooth muscle cells (smc) isolated from norm al and atherosclerotic hum an aorta were studied using the patch-clam p technique. It was shown tha t smc from norm al hum an aorta possess a homogeneous population of norm al C a2+-dependent K + channels. In atherosclerotic aorta two kinetically different types of these channels could be distinguished: along with norm al ‘lo n g ’ (L)-type channels there appeared channels o f ‘sh o rt’ (s)-type. U nder similar conditions s-type channels had about a four times shorter m ean open time. A bout five times higher [C a2+]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 hum an aorta. Thus, it can be suggested th a t during the developm ent of atherosclerosis a population of smc with s-type Ca -dependent K + channels appears i