title: [Effect of carvedilol on T-type calcium current in myocytes of non-infarcted area of the rabbit healed myocardial infarction].
abstract: This article reports the investigation of the effect of carvedilol (Car) on T-type calcium current (I(Ca,T)) of noninfarcted ventricular myocytes in rabbit models of healed myocardial infarction (HMI). Rabbits with left anterior descending artery ligation were prepared and allowed to recover for 8 weeks, as HMI group. Animals undergoing an identical surgical procedure without coronary ligation were served as the sham-operated group (sham group). Whole cell voltage-clamp techniques were used to measure and compare currents in cells from the different groups. Noting that I(Ca,T) density in HMI cells increased markedly to -2.36 +/- 0.12 pA/pF (at -30 mV) compared with cells of sham, where little I(Ca,T) (-0.35 +/- 0.02 pA/pF) was observed. Meanwhile, further analysis revealed a significant hyperpolarizing shift of steady-state activation curve of I(Ca,T) in HMI cells, where the time constants of deactivation were prolonged and the time of recovery from inactivation was shortened. Finally, the amplitude of I(Ca,T) was increased. Carvedilol (1 micromol x L(-1)) was found to decrease the amplitude of I(Ca,T) to -1.38 +/- 0.07 pA/pF through inhibiting process of I(Ca,T) activation. Furthermore, carvedilol delayed recovery from inactivation of I(Ca,T) and shortened the time constants of deactivation in HMI cells. This study suggested that the application of carvedilol in HMI cells contributes to the dynamic changes in I(Ca,T) and may account for reduction of incidence of arrhythmia after myocardial infarction.
authors.affiliation: Provincial Clinical Medicine College of Fujian Medical University, Fujian 350001, China.
authors.forename: Min
authors.initials: M
authors.lastname: Lin
authors.forename: Cai-Xing
authors.initials: CX
authors.lastname: Zhu
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Jin-Liao
authors.initials: JL
authors.lastname: Gao
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Fu
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Lan
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Jian-Cheng
authors.initials: JC
authors.lastname: Zhang
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D020747:Calcium Channels, T-Type / Q000187:drug effects*; D002227:Carbazoles / Q000494:pharmacology*; D000077261:Carvedilol; D005260:Female; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D011412:Propanolamines / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D000319:Adrenergic beta-Antagonists; D020747:Calcium Channels, T-Type; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol