['To investigate endothelin 1 (Et1)-dependent Ca(2+)-signaling at the cellular and subcellular levels in retinal arteriolar myocytes.', 'Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using confocal laser microscopy.', 'Basal [Ca(2+)](i), subcellular Ca(2+)-sparks, and cellular Ca(2+)-oscillations were all increased during exposure to Et1 (10 nM). Ca(2+)-spark frequency was also increased by 90% by 10 nM Et1. The increase in oscillation frequency was concentration dependent and was inhibited by the EtA receptor (Et(A)R) blocker BQ123 but not by the EtB receptor antagonist BQ788. Stimulation of Ca(2+)-oscillations by Et1 was inhibited by a phospholipase C blocker (U73122; 10 μM), two inhibitors of inositol 1,4,5-trisphosphate receptors (IP(3)Rs), xestospongin C (10 μM), 2-aminoethoxydiphenyl borate (100 μM), and tetracaine (100 μM), a blocker of ryanodine receptors (RyRs).'] Does endothelin 1 stimulate Ca2+-sparks and oscillations in retinal arteriolar myocytes via IP3R and RyR-dependent Ca2+ release?