title: [Age-related changes in transient outward potassium current of rat ventricular myocyte].
abstract: The study aimed to investigate the age-related changes and drug reactions of transient outward potassium current (Ito) of ventricular myocytes. Twenty-eight Sprague Dawley rats were divided into young (3-5 months), adult (13-15 months) and aged (22-24 months) groups, and Ito currents of isolated myocytes from each group were recorded respectively by patch-clamp. The perfusion of 2.0 mmol/L 4-AP or 1.0 μmol/L isoproterenol was added respectively in each group, and the changes of Ito were observed. In comparison with young and adult groups, Ito densities of ventricular myocytes in aged group was significantly increased, the curve of steady-state activation of Ito shifted to the left, the close-state inactivation rate significantly decreased, and recovery rate from the steady-state inactivation became quicker. However, no significant changes could be detected for the Ito steady-state inactivation of ventricular myocytes in aged group. The similar responsiveness to 4-AP was observed in all three groups, but the responsiveness to isoproterenol was weaker in the aged group (55.9%) than in the other two groups (127.5% and 125.8%). In conclusion, the results show that Ito of rat ventricular myocyte of aging heart has increased current density and decreased response to isoproterenol.
authors.affiliation: Institute of Geriatric Cardiology, the PLA General Hospital, Beijing 100853, China.
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Fu
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Mei-Yan
authors.initials: MY
authors.lastname: Chen
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Yan-Li
authors.initials: YL
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Tong
authors.initials: T
authors.lastname: Yin
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000375:Aging; D000818:Animals; D002478:Cells, Cultured; D006352:Heart Ventricles / Q000166:cytology; D007545:Isoproterenol / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015221:Potassium Channels; D015761:4-Aminopyridine; D007545:Isoproterenol