[Properties of the smooth muscle cell endoplasmic reticulum calcium pump].
In experiments with 45Ca2+ conducted on digitonin-treated (0.1 mg/ml) myometrium cells suspension, the properties of ruthenium red-insensitive, oxalate- or phosphate-stimulated and thapsigargin- or cyclopiasonic acid-suppressed Mg2+, ATP-dependent calcium pump of myometrium sarcoplasmic reticulum was studied. The Ca2+ accumulation increased linearly in time up to 10 min, the average initial rate was 80-130 pmol Ca2+/10(6) cells per min. In the presence of 10 mM oxalate the values of the activation constant KMg for Mg2+ and K(m) for ATP were 0.6 and 1.0 mM, respectively. The relative efficiency of the different cations in insuring of the ATP-dependent Ca2+ accumulation was Mg2+ > Mn2+ = Co2+ >> Ni2+; the Ca2+ accumulation was not observed in the presence of 3 mM Zn2+ or Cu2+. We observed the suppression of calcium pump activity by different inhibitors such as thapsigargin, cyclopiazonic acid, p-chloromercuribenzoic acid, eosin Y ad Na3 VO4: the values of K0.5 were 2.0 nM, 0.3 microM, 0.6 microM, 0.8 microM and 45 microM respectively. The conclusion was made that suspension of myometrial cells treated with digitonin represent a suitable experimental model for studying the properties of myometrium sarcoplasmic reticulum calcium pump.
Babich
L G
LG
A.V. Palladin Institute of Biochemistry National Academy of Sciences of Ukraine, Kyiv.
Shlykov
S G
SG
Strutinskaia
N A
NA
Kosterin
S A
SA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008670:Metals / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism* / Q000648:ultrastructure; D009215:Myometrium / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats
D004791:Enzyme Inhibitors; D008670:Metals; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases