Cloning and expression of a rat cardiac delayed rectifier potassium channel

Markus Paulmichl, Patricia Nasmith, Renate Hellmiss, Karen Reed, Walter A. Boyle, Jeanne M. Nerbonne, Ernest G. Peralta, David E. Clapham

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Abstract

We have cloned a cDNA (designated RAK) coding for a delayed-rectifier K current (IRAK) from adult rat heart atrium and expressed it in Xenopus oocytes. RAK differs from the cloned rat brain K current, BK2 [McKinnon, D. (1989) J. Biol. Chem. 264, 8230-8236], by one amino acid at residue 411. RAK expressed in oocytes compares closely to the intrinsic adult rat atrial delayed-rectifier current measured by using whole-cell recording of single isolated cells. Northern blot analysis confirmed the presence of the channel in adult rat atrium, and to a lesser extent, in rat ventricle. IRAK activates with time constants ranging from 58 ms at -20 mV to 6 ms at +60 mV and does not show significant inactivation over 800 ms. It is blocked by 4-aminopyridine > barium > > tetraethylanunonium chloride, which is similar to the relative potencies of these blockers on the native delayed rectifier current. We conclude that the main delayed rectifier K current in adult rat atria is virtually identical to a neuronal delayed rectifier, BK2.

Original languageEnglish
Pages (from-to)7892-7895
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume88
Issue number17
DOIs
StatePublished - Jan 1 1991

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