title: [High intracellular Mg²⁺ affects the activities of L-type calcium channel in guinea- pig ventricular myocytes].
abstract: This study is aimed to investigate the effects of high intracellular Mg²⁺ on L-type calcium channel in guinea-pig ventricular myocytes. The cardiomyocytes were acutely isolated with enzyme digestion method. By adopting inside-out configuration of patch clamp technique, single channel currents of the L-type calcium channel were recorded under different intracellular Mg²⁺ concentrations ([Mg²⁺]i). In control group, which was treated with 0.9 mmol/L Mg²⁺, the relative activity of calcium channel was (176.5 ± 34.1)% (n = 7). When [Mg²⁺]i was increased from 0.9 to 8.1 mmol/L (high Mg²⁺ group), the relative activities of calcium channel decreased to (64.8 ± 18.1)% (n = 6, P < 0.05). Moreover, under 8.1 mmol/L Mg²⁺, the mean open time of calcium channel was shortened to about 25% of that under control condition (P < 0.05), but the mean close time of calcium channel was not altered. These results suggest that high intracellular Mg²⁺ may inhibit the activities of L-type calcium channel, which is mainly due to the shortening of the mean open time of single L-type calcium channel.
authors.affiliation: Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110001, China. lyhao@mail.cmu.edu.cn.
authors.forename: Mei-Mi
authors.initials: MM
authors.lastname: Zhao
authors.forename: Wen-Wen
authors.initials: WW
authors.lastname: Lian
authors.forename: Rui
authors.initials: R
authors.lastname: Sun
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Wang
authors.forename: Rui
authors.initials: R
authors.lastname: Feng
authors.forename: Hui-Yuan
authors.initials: HY
authors.lastname: Hu
authors.forename: Xue-Fei
authors.initials: XF
authors.lastname: Sun
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Hao
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology*; D006168:Guinea Pigs; D008274:Magnesium / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D018408:Patch-Clamp Techniques
chemical_list: D020746:Calcium Channels, L-Type; D008274:Magnesium