Sarcoplasmic reticulum interacts with the Ca(2+) indicator precursor fura-2-am.
Fura-2-am, the pentaester precursor of the fluorescent Ca(2+) indicator fura-2, is modified when it is exposed to isolated skeletal muscle sarcoplasmic reticulum vesicles. The modified fura-2-am has enhanced fluorescence, is not sensitive to Ca(2+), and is partially bound to the SR membrane. The isolated product is further converted into fura-2 by esterase. It is suggested that the SR-induced modification is a selective enzymatic hydrolysis of only some of the five ester moieties on fura-2-am. A structure is proposed to account for the results. The potential for this effect of SR on fura-2-am to cause complications in measurements of in vivo intracellular free [Ca(2+)] is noted.
D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000032:analysis*; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects*; D012995:Solubility; D013050:Spectrometry, Fluorescence
D001572:Benzofurans; D005456:Fluorescent Dyes; C049925:fura-2-am; D002118:Calcium; D016257:Fura-2