Roles of the voltage-gated K+ channel subunits, Kv 1.5 and Kv 1.4, in the developmental changes of K+ currents in cultured neonatal rat ventricular cells.
To investigate the roles of voltage-gated K+ channel subunits, Kv 1.5 and Kv 1.4, in the developmental regulation of K+ currents, we determined the K+ channel activities and the distributions of K+ channel subunits in the same single cultured neonatal rat ventricular cells, using a whole-cell patch-clamp technique and an immunocytochemical analysis of K+ channel proteins. In 5-day cultured cells, two types of 4-aminopyridine (4-AP)-sensitive and rapidly activating K+ currents, the transient outward current (Ito) and the ultrarapid delayed rectifier (IKur), could be distinguished. A small proportion of 5-day cells expressing sole IKur demonstrated an intense anti-Kv 1.5 antibody labeling with punctate distribution outlining the cells, while a weak staining was observed in the majority of 5-day cells expressing sole Ito. At day 15 of cell culture, only Ito was present with a lower level of the immunocytochemical expression of Kv 1.5 channel protein. Staining of the Kv 1.4 channel protein was qualitatively similar in the 5-day cells expressing either Ito or IKur. However, anti-Kv 1.4 antibody did not label the 15-day cultured cells showing remarkably increased Ito density. Our results strongly indicate that the Kv 1.5 channel expression may underlie the developmental regulation of IKur, while Kv 1.4 channel does not contribute to the postnatal increase in Ito.
Guo
W
W
Dept. of Circulation, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-01, Japan.
Kamiya
K
K
Toyama
J
J
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002478:Cells, Cultured; D006321:Heart / Q000254:growth & development*; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016276:Ventricular Function
D015221:Potassium Channels