Calcium waves in skinned cardiac myocytes evoked by two-photon excitation photolysis of caged calcium

In rat ventricular myocytes chemically skinned with saponin, a local rise o f [Ca2+] was achieved by two-photon excitation photolysis (TPP) of the cage d Ca2+ compound 1-(2-nitro-4,5-dimethoxyphenyl)-N, N, N ', N ' -tetrakis[(o xycarbonyl)methyl]-1,2-ethanediamine (DM-nitrophen), Confocal Ca2+ images, by use of fluo-3, were simultaneously collected. TPP of DM-nitrophen induce d Ca2+ waves propagating over the myocyte, and the local rise of [Ca2+] at the site of photolysis sustained for 50-60 ms. These TPP-induced Ca2+ event s were completely suppressed by ryanodine (10 muM), suggesting that Ca2+ re lease resulting from TPP of DM-nitrophen triggered regenerative Ca2+ releas e from the neighboring sarcoplasmic reticulum, The present techniques shoul d be useful to investigate the interaction of elementary Ca2+ events, the p rocess leading to global Ca2+ movements, in cardiac myocytes and other type s of cells.