Developmental changes in action potential prolongation by K+-channel blockers in chick myocardium.
The effects of K(+)-channel blockers on the action potential duration of the myocardium were examined in isolated right ventricles from the 7 - 10-day-old, 11 - 13-day-old, and 14 - 20-day-old embryo and 1 - 7-day-old hatched chicks. E-4031 significantly prolonged action potential duration at all developmental stages examined; the prolongation was largest in the 11 - 13-day-old embryo and was accompanied by early after-depolarizations. Chromanol 293B showed smaller prolongation at all stages examined. Terfenadine prolonged action potential duration in the 11 - 13-day-old embryo, but not in other stages. Thus, the chick ventricular myocardium changes its repolarization properties during development.
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, Chiba 274-8510, Japan.
Hideaki
H
Nouchi
Naoaki
N
Kiryu
Mikio
M
Kimata
Yayoi
Y
Tsuneoka
Shogo
S
Hamaguchi
Iyuki
I
Namekata
Akira
A
Takahara
Koki
K
Shigenobu
Hikaru
H
Tanaka
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology; D002642:Chick Embryo; D051668:Delayed Rectifier Potassium Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D006352:Heart Ventricles / Q000187:drug effects*; D008133:Long QT Syndrome / Q000139:chemically induced / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D015221:Potassium Channels / Q000378:metabolism*
D051668:Delayed Rectifier Potassium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels