[Synergism of energy-dependent calcium fluxes through smooth muscle cell membrane].
Some peculiarities of Ca2+ exchange in the vesiculate fraction of myometrium sarcolemma during separate and combined functioning of the Ca-pump and Na(+)-Ca2+ antiporter in the presence of initial physiologically significant transmembrane gradients of Ca2+ and Na+ were studied. The effect of synergistic activation of the transfer substrate accumulation inside the vesicles was demonstrated. This effect was observed both in the presence of inside-out directed Ca2+ gradient and in its absence. At Ca2+ concentrations in the extravesicular space equimolar to those in contracted myocytes (5 x 10(-6)-10(-5) M), the co-functioning of the cationic antiporter and Ca-pump provided for effective translocation of the transfer substrate to the vesicles which fully prevented the dissipation of the initial oppositely directed Ca2+ gradient. The synergism of energy-dependent calcium fluxes seemed to be unrelated to changes in the chemical composition of the ATP-containing incubation medium responsible for the induction of Mg2+, ATP- and Na(+)-dependent Ca2+ transfer (addition to the medium of Mg2+ and isotonic replacement of Na+ for choline+, respectively). It is concluded that the observed synergism is due to the stimulating effect of the Na+ gradient on the turnover number of the myometrium sarcolemma Ca-pump.
Burchinskaia
N F
NF
Kosterin
S A
SA
Babich
L G
LG
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology; D002413:Cations, Divalent; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D008274:Magnesium / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology; D009130:Muscle, Smooth / Q000378:metabolism*; D009215:Myometrium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger; D013552:Swine
D002352:Carrier Proteins; D002413:Cations, Divalent; D008565:Membrane Proteins; D019831:Sodium-Calcium Exchanger; D000255:Adenosine Triphosphate; D012964:Sodium; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium
Sinergizm énergozavismiykh kal'tsievykh potokov cherez plazmaticheskuiu membranu gladkomyshechnykh kletok.