[Ca 2+ outflow from sarcoplasmic reticulum vesicles during changes in membrane potential, Ca2+ concentration and pH].
The concentration gradient Ca2+ outflux from the vesicles of the fragmented sarcoplasmic reticulum of rabbit skeletal muscles has been studied under conditions of the induced membrane potential, the concentrations of Ca2+ and H+ in the medium washing over the vesicles being different. The Ca2+ outflux from vesicles is shown to be the same with a decrease of the membrane potential from--80 down to -10 mV and gets higher with the zero and subsequent positive values of the latter. A significant intensification of the Ca2+ outflux from vesicles under the effect of external-vesicular Ca2+ has been observed at its concentration of 10(-5) M. Against this background of external-vesicular Ca2+ and zero value of the membrane potential either exogenous AMP or the pH increase from 6.5 up to 7.8 favour a release of more than 70% of passively accumulated Ca2+. The pH effect grows with a decrease in the external-vesicular concentration of Ca2+. A conclusion is drawn on the significance of protons in the regulation of the Ca2+ release from the sarcoplasmic reticulum.
Tugaĭ
V A
VA
Diadiusha
G P
GP
Zakharchenko
A N
AN
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009132:Muscles / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000502:physiology; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism* / Q000502:physiology
D003470:Culture Media; D000249:Adenosine Monophosphate; D011188:Potassium; D002118:Calcium
Vykhod Ca 2+ iz vezikul sarkoplazmaticheskogo retikuluma pri izmenenii membrannogo potentsiala, kontsentratsii Ca2+ i pH.