%0 Journal Article
%T Contribution of spontaneous L-type Ca2+ channel activation to the genesis of Ca2+ sparks in resting cardiac myocytes
%A Guangqin Zhang
%A Yu Fu
%A Dongmei Yang
%A Xuemei Hao
%A Shuhua Bai
%A Yiqun Tang
%A Edward G. Lakatta
%A Caihong Wu
%A Heping Cheng
%J Science China Life Sciences
%@ 1869-1889
%D 2004
%I 
%R 10.1360/02yc0234
%X Ca2+ sparks are the elementary events of intracellular Ca2+ release from the sarcoplasmic reticulum in cardiac myocytes. In order to investigate whether spontaneous L-type Ca2+ channel activation contributes to the genesis of spontaneous Ca2+ sparks, we used confocal laser scanning microscopy and fluo-4 to visualize local Ca2+ sparks in intact rat ventricular myocytes. In the presence of 0.2 mmol/L CdCI2 which inhibits spontaneous L-type Ca2+ channel activation, the rate of occurrence of spontaneous Ca2+ sparks was halved from 4.20 to 2.04 events/(100 ¦Ìm ¡¤ s), with temporal and spatial properties of individual Ca2+ sparks unchanged. Analysis of the Cd2+-sensitive spark production revealed an open probability of ~10 -5 for L-type channels at the rest membrane potentials (-80 mV). Thus, infrequent and stochastic openings of sarcolemmal L-type Ca2+ channels in resting heart cells contribute significantly to the production of spontaneous Ca2+ sparks.
%K Ca2+ sparks
%K L-type Ca2+ channels
%K cardiac myocytes
%K confocal microscopy
%U http://link.springer.com/article/10.1360/02yc0234