%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