Abstract
Using a standard patch-clamp technique in the perforated patch configuration, we studied the effect of a highly specific membrane-permeable inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaM-KII), KN-93, on fast outward A-type potassium current in isolated smooth-muscle cells (SMCs) of an epididymal region of the rat vas deferens. This inhibitor significantly changed the dynamics of the studied current; in particular, it increased the rate of inactivation and considerably slowed down the recovery after inactivation. In the presence of 5 µM KN-93, we observed a moderate (nearly by 20%) decrease in the peak amplitude of fast A-type current. Based on the data obtained, we conclude that voltage-sensitive fast A-type potassium current in SMCs of the epididymal part of the rat vas deferens can be significantly regulated by the activity of CaM-KII. Therefore, by influencing the kinetic characteristics of the above current, this enzyme can be indirectly involved in the control of electrical activity in SMCs.
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