Cloning and expression of a K sub(v)1.2 class delayed rectifier K super(+) channel from canine colonic smooth muscle

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 90; no. 20; pp. 9659 - 9663
• Main Authors: Hart, P J, Overturf, KE, Russell, S N, Carl, A, Hume, J R, Sanders, K M, Horowitz, B
• Format: Journal Article
• Language: English
• Published: 01-01-1993
• ISSN: 0027-8424

A cDNA (CSMK1) encoding a delayed rectifier K super(+) channel of the K sub(v)1.2 class was cloned from canine colonic circular smooth muscle and expressed in Xenopus oocytes. These channels appear to be uniquely expressed in gastrointestinal muscles and may participate in the electrical slow wave activity. Functional expression of CSMK1 in Xenopus oocytes demonstrated a K super(+) current that activated in a voltage-dependent manner upon depolarization. This current was highly sensitive to 4-aminopyridine (IC sub(50), 74 mu M). A low-conductance K super(+) channel was identified in inside-out patches from oocytes injected with CSMK1. This channel displayed a linear current-voltage relation with a slope conductance of 14 pS. The channels were blocked in a concentration-dependent manner by 4-aminopyridine.