title: Development of inwardly rectifying K+ channel family in rat ventricular myocytes.
abstract: The ATP-sensitive K+ current (I(K,ATP)), the inward rectifier K+ current (I(K1)), and the acetylcholine-activated K+ current (I(K,ACh)) were recorded in fetal, neonatal, and adult rat ventricular myocytes using the patch-clamp technique. The density (pA/pF) of I(K1) increased from gestation day 10 through neonatal day 1 and then decreased after neonatal day 30. The density of I(K,ATP) activated maximally by metabolic inhibition changed in parallel with the I(K1) density, and the density of I(K,ATP) channel distribution was 1.3 times higher than that of I(K1) throughout the development. We failed to observe developmental changes in the single-channel conductance and the mean open time of I(K1) and I(K,ATP) channels. However, the open probability of the I(K,ATP) channel was lower in fetuses, and the sensitivity to ATP was highest in 1-day neonates. I(K,ACh) were present in the ventricle at all stages of development but at a much lower density than in atrium. The relationship between the resting membrane potential and the development of the inwardly rectifying K-channel family is discussed.
authors.affiliation: Department of Physiology and Biophysics, Faculty of Medicine, Kyoto University, Japan.
authors.forename: L H
authors.initials: LH
authors.lastname: Xie
authors.forename: M
authors.initials: M
authors.lastname: Takano
authors.forename: A
authors.initials: A
authors.lastname: Noma
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017609:Barium Compounds / Q000494:pharmacology; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000494:pharmacology; D005314:Embryonic and Fetal Development; D051638:Ether-A-Go-Go Potassium Channels; D005318:Fetal Heart / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D005905:Glyburide / Q000494:pharmacology; D006321:Heart / Q000254:growth & development*; D006352:Heart Ventricles; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D008564:Membrane Potentials / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D015221:Potassium Channels / Q000096:biosynthesis* / Q000187:drug effects / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D051381:Rats
chemical_list: D017609:Barium Compounds; D027682:Cation Transport Proteins; D002712:Chlorides; D051638:Ether-A-Go-Go Potassium Channels; D007461:Iodoacetates; C092509:KCNH6 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C024986:barium chloride; D000255:Adenosine Triphosphate; D005905:Glyburide; D019807:Iodoacetic Acid