["The observation of local 'elementary' Ca2+ release events (Ca2+ sparks) through ryanodine receptor (RyR) channels in the sarcoplasmic reticulum (SR) has changed our understanding of excitation-contraction (EC) coupling in cardiac and smooth muscle. In arterial smooth muscle, Ca2+ sparks have been suggested to oppose myogenic vasoconstriction and to influence vasorelaxation by activating co-localized Ca2+ activated K+ (K(Ca)) channels (STOCs). However, all prior studies on Ca2+ sparks have been performed in non-human tissues.", 'In order to understand the possible significance of Ca2+ sparks to human cardiovascular function, we used high spatial resolution confocal imaging to record Ca2+ sparks in freshly-isolated, individual myocytes of human coronary arteries loaded with the Ca2+ indicator fluo-3.', "Local SR Ca2+ release events recorded in human myocytes were similar to 'Ca2- sparks' recorded previously from non-human smooth muscle cells. In human myocytes, the peak [Ca2+]i amplitudes of Ca2+ sparks (measured as F/F0) and width at half-maximal amplitude were 2.3 and 2.27 microm, respectively. The duration of Ca2+ sparks was 62 ms. Ca2+ sparks were completely inhibited by ryanodine (10 micromol/l). Ryanodine-sensitive STOCs could be identified with typical properties of K(Ca) channels activated by Ca2+ sparks."] Does calcium spark in human coronary artery smooth muscle cells resolved by confocal imaging?