[Two components of sodium-azide insensitive Mg2+,ATP-dependent Ca2+ transport in ureteral smooth muscle membrane structures].

The effects of Ca(2+)-precipitating anions (oxalate and phosphate) and effective inhibitors of endo/sarcoplasmic reticulum calcium pump (thapsigargin and cyclopiazonic acid) on azide-insensitive (5 mM) Mg2+,ATP-dependent Ca2+ accumulation in microsomes of ureter smooth muscle cells were studied. Oxalate (0-20 mM) and phosphate (0-60 mM) stimulate Mg2+,ATP-dependent Ca2+ accumulation. Thapsigargin and cyclopiazonic acid at 100 nM and 20 microM, respectively, completely inhibited (i.

[Inhibiting effect of ADP-ribosylation by pertussis toxin on passive transport of Ca2+ into the cell membrane of porcine myometrium].

ADP-ribosylation by whooping cough toxin of protein components of inside-out oriented vesicles of pig myometrium plasma membranes under conditions of their depolarization results in significant inhibition of passive transport of Ca2+ ions. The inhibiting effect is dose- and time-dependent. rho-Chloromercuribenzoate (0.

[Calmodulin-induced activation of ATP-dependent Ca2+ transport in plasma membranes of the myometrium].

Calmodulin activates the ATP-dependent transport of Ca2+. The V0 value for this reaction in the absence of calmodulin is 0.82, that in the presence of 10(-7) M calmodulin is 5 times as high, i.

[Regulation by Ca2+-calmodulin-dependent phosphorylation of passive transport of Ca2+ in the myometrial sarcolemma].

Closed vesiculate preparations of pig myometrium sarcolemma (predominantly with inside-out orientation) are characterized by passive permeability for Ca2+. The kinetics of Ca2+ release from the vesicles is exponential. Using the grapho-analytical subtraction method, the kinetic parameters of this reaction were determined.

[Ca2+ (calmodulin)-dependent phosphorylation of plasma membranes of pig myometrium].

The high-purified vesicles of pig myometrium sarcolemma closed, mainly, so that the cytoplasmatic side is outside possess the Ca2+ (calmodulin)-dependent protein kinase activity. The initial rate of the endogenic phosphorylation without exogenic calmodulin is 6.3 and with its presence--10.

[Calmodulin-dependent regulation of Ca,Mg-ATPase activity in plasma membranes of the swine myometrium].

Highly purified plasma membrane (PM) preparations of pig myometrium were found to contain 0.91 +/- 0.22 microgram calmodulin per mg of PM protein.

[Isolation and characteristics of the plasma membrane fraction from the swine myometrium].

An accelerated method is developed for isolating a fraction of plasma membranes of pig myometrium using ultracentrifugation within the sucrose density gradient (15% and 30%). The membranes possessed the high activity of 5'-nucleotidase and Na+, K+-ATPase and the low activity of rhotenon-insensitive NADH-cytochrome c reductase. The vesicularized preparations of plasma membranes are able of ATP-dependent accumulation of Ca2+ (7.

[Ca2+-calmodulin-activated cyclic nucleotide phosphodiesterase from the rabbit myometrium].

Two forms of soluble phosphodiesterase of cyclic nucleotides separating by DEAE-cellulose ion-exchange chromatography and not only differing in physicochemical and catalytic parameters but also differently regulated by calmodulin are found in the doe myometrium. Calmodulin with 10(-7)-10(-5) M concentrations of Ca2+ promotes the two-fold activation of the 3':5'-AMP (but not of 3':5'-GMP) hydrolysis by the first form of phosphodiesterase. Trifluoperazine (10 microM) lowers the activating action of calmodulin.

[Properties of cyclic nucleotide phosphodiesterase of the rabbit myometrium in various functional states].

Chromatography on DEAE-cellulose of a soluble sulfate-precipitated fraction of cyclic nucleotide phosphodiesterase from rabbit myometrium revealed two 3':5'-GMP and 3':5'-AMP-hydrolase activities. 3':5'-GMP phosphodiesterase (fraction I) was eluted with 0.15-0.

[Method for obtaining muscle adenosine monophosphoric acid].

A method is developed for obtaining 5'-AMP with utilization of the partially purified potato apyrase. In this case the extract of muscles or the medical preparation of ATP not corresponding to the standard requirements may be initial product instead of the purified ATP.