[Changes in intravesicular pH during Ca2+ transport in the sarcoplasmic reticulum].
Studies with the use of [3H]acetate as an delta pH-indicator have established that pH in the native vesicles of sarcoplasmic reticulum is by 0.54 unit lower, than its extra-molecular value (6.5 units). The double [3H] and radioactive [3H] and [45Ca2+] labels were used to show that Ca2+ transport into the sarcoplasmic reticulum vesicles is accompanied by an increase in intravesicular pH. Carbonylcyanide-m-chlorophenylhydrazone, a protonophore, stimulates the equalization of the pH gradient (H+ removal) which is not accompanied by changes in the Ca2+ transport. In the presence of ionophore A23187 Ca2+ and [3H]acetate do not accumulate in vesicles in the ATP-dependent process. This indicates H+ removal from the vesicles only when there is the Ca2+ gradient creation and the absence of the close conjugation of Ca3+/2H+ realized by Ca2+-ATPase of sarcoplasmic reticulum.
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D009132:Muscles / Q000378:metabolism* / Q000648:ultrastructure; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure
D011092:Polyethylene Glycols; D017830:Octoxynol; D002118:Calcium
Izmenenie vnutrivezikuliarnogo pH pri transporte Ca2+ v sarkoplazmaticheskom retikulume.