Abstract
Diverse expression of voltage dependent K+ (Kv) channels was examined in smooth muscles (SMs) ; carotid artery (CA), mesenteric artery (MA), urinary bladder (UB), and vas deferens (VD) of the rat, using RT-PCR based analyses. Among eight Kv channel subtypes examined (Kv 1.1, Kv 1.2, Kv 1.5, Kv 1.6, Kv 2.1, Kv 2.2, Kv 3.1, and Kv 3.2), expression of three delayed rectifier Kv (KD) channel (Kv 1.2, Kv 1.5, and Kv 2.1) transcripts was observed in these SMs. To determine precisely the expression levels of the transcripts encoding KD subtypes, those of three KD subtypes (Kv 1.2, Kv 1.5, and Kv 2.1) were determined by competitive PCR. In vascular SM tissues, CA and MA, Kv 1.2 and Kv 1.5 transcripts were expressed at relatively high levels, whereas in visceral SM tissues, UB and VD, Kv 2.1 transcripts were expressed at the relatively high levels. These results suggest that the diverse expression of KD subtypes is, at least in part, responsible for differences in electrical excitability and also for the variation of the electrophysiological and pharmacological phenotypes as tonic and phasic SMs.
