title: [ATPase activity and uptake of calcium by a fraction of plasma membrane of rabbit myometrium at functional rest and in pregnancy].
abstract: Study of the dependence of 45CA2+ binding on its concentration demonstrated that both at functional rest (FR) and in pregnancy the Ca-binding ability of rabbit myometrium subcellular fractions is decreased in the following order: sarcolemma greater than microsomes greater than mitochondria approximately nuclei. The values of Kd for the sarcolemmal Ca2+-binding site complex are identical in both cases (80-87 micro M); however, the maximal calcium-binding capacity of pregnancy is 1.5 times less than in FR. In the plasma membrane fraction of pregnant rabbits the adenosine triphosphatase activity is decreased. The rate of ATP-dependent 45Ca2+ uptake in sarcolemmal fraction is significantly higher than in other subcellular fractions in both conditions. It is concluded that at FR and in pregnancy sarcolemma plays a key role in regulation of ionized calcium concentration in myometrium cells.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D005260:Female; D007700:Kinetics; D009215:Myometrium / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011817:Rabbits; D012508:Sarcolemma / Q000201:enzymology; D014599:Uterus / Q000378:metabolism*
chemical_list: D000251:Adenosine Triphosphatases; D002118:Calcium
vernacular_title: ATPaznaia aktivnost' i akkumuliatsiia kal'tsiia vo fraktsii plazmaticheskikh membran miometriia krol'chikh v sostoianii funktsional'nogo pokoia i pri beremennosti.