Inhibitors of Ca2+ release from the isolated sarcoplasmic reticulum. I. Ca2+ channel blockers.
The effects of Ruthenium red and tetracaine, which inhibit Ca2+-induced Ca2+ release from the isolated sarcoplasmic reticulum (e.g., Ohnishi, S.T. (1979) J. Biochem. (Tokyo) 86, 1147-1150), on several types of Ca2+ release in vitro were investigated. Ca2+ release was triggered by several methods: (1) addition of quercetin or caffeine, (2) Ca2+ jump, and (3) replacement of potassium gluconate with choline chloride to produce membrane depolarization. The time-course of Ca2+ release was monitored using stopped-flow spectrophotometry and arsenazo III as a Ca2+ indicator. Ruthenium red inhibited all of these types of Ca2+ release with the same concentration for half-inhibition C1/2 = 0.08-0.10 microM. Similarly, tetracaine inhibited these types of Ca2+ release with C1/2 = 0.07-0.11 mM. Procaine also inhibits both types of Ca2+ release induced by method 2 and 3 with C1/2 = 0.67-1.00 mM. These results suggest that Ruthenium red, tetracaine and procaine interfere with a common mechanism of the different types of Ca2+ release. On the basis of several pieces of evidence we propose that Ruthenium red and tetracaine block the Ca2+ channel of sarcoplasmic reticulum.
B
B
Antoniu
D H
DH
Kim
M
M
Morii
N
N
Ikemoto
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D011343:Procaine / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology; D011817:Rabbits; D012430:Ruthenium Red / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D013748:Tetracaine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D007473:Ion Channels; D013748:Tetracaine; D012430:Ruthenium Red; D002110:Caffeine; D011343:Procaine; D011794:Quercetin; D002118:Calcium