Human leukemia CEM C-1 cells possess a high affinity binding site for farnesol.

Binding of 15-carbon isoprenoid farnesol in human acute leukemia CEM C-1 cells has been studied by addition of radio-labeled isoprenoid to cell growth medium. Significant time-dependent accumulation of the cell-associated radioactivity was detected at 37 degrees C. When experiments were carried out at 4 degrees C, about 10 times decrease in cell labeling was observed.

[Ca2+ metabolism in the sarcoplasmic reticulum of skeletal muscle after surgical denervation].

The ability of sarcoplasmic reticulum to regulate Ca(2+)-metabolism was studied at different terms after surgical denervation. The increase of Ca(2+)-ATP-ase activity, intensification of active Ca(2+)-accumulation under insignificant change of passive Ca(2+)-outflow from sarcoplasmic reticulum vesicles were observed 3-days after denervation. At more remote terms 14 days and 28 days after denervation all these parameters decreased except for Km: Ca(2+)-ATP activity and active Ca2+ accumulation decreased below normal level.

[Effect of fluoroaluminate on the passive transport of calcium in the plasma membrane fraction of the pig myometrium].

Study of the effect of aluminium, fluoride-ions and fluoroaluminium on the passive transport of Ca2+ through the plasma membrane of the myometrium cells has shown that 10 microM of Al3+, 1 mM of F- and the both ions taken in the mentioned concentrations do not affect this process. At the same time 10 mM of F- as well as 10 microM of Al3+ together with 10 mM of F- inhibit a passive output of calcium from vesicles. The results obtained suppose that inhibitory regulation of the passive transport of calcium in the myometrium sarcolemma is executed through Gi-protein.

[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.

[The effect of antibodies against Ca2(+)-ATPase and its hydrophobic fragment on the activity of this enzyme and on the passive transport of Ca2(+)].

It is shown that both Ca(2+)-ATPase and its hydrophobic fragment are immunogenic factors. A region between hydrophobic and hydrophilic parts of Ca(2+)-ATP-ase is immunogenic. These antibodies clearly inhibit inflow and outflow of Ca2+ through a hydrophobic fragment reconstructed into liposomes and do not influence Ca(2+)-ATPase activity.

[Analysis of the role of calcium in analgesic action of non-narcotic analgesics and calcium channel blockers].

In the mice hot-plate test we have compared analgesic effect of calcium channel blockers and new non-narcotic analgesic antiinflammatory agent PV-107: verapamil > fenigidin > PV-107. Simultaneously we have shown strong correlation (r - 0.82) between analgesic effect and 45Ca2+ efflux of cardiac membrane in depolarizing media in vitro.

[Phosphorylation of myocardial sarcolemma proteins during induction of the phosphatidylinositol cycle in isolated perfused rabbit heart].

Phosphorylation of cardiac sarcolemma proteins under stimulation of M-receptors by agonist carbacholine used to stimulate phosphatidylinositide cycle, was investigated in the isolated, rabbit heart perfused with 32Pi. Carbacholine (10(-7) stimulates the polyphosphoinositide metabolism which is expressed in the activated incorporation of 32P from [gamma-32P]ATP in polyphosphoinositide as well as in the increased content of the labelled inositol trisphosphate released through phosphatidylinositol-4,5-bisphosphate break-down by phospholipase C. The diacylglycerol produced simultaneously with inositol triphosphate as a second messenger activates the protein kinase C.

The ion-conducting properties of Ca2+ ATPase in rabbit skeletal muscle sarcoplasmic reticulum.

Ca2+ ATPase was isolated from rabbit skeletal muscle sarcoplasmic reticulum and used to form structures resembling potential-dependent calcium channels within the membrane lipid bilayer of liposomes. The orientation of these structures in the bilayer was dependent on the conditions used for enzyme incorporation. The results obtained indicate that Ca2+ ATPase may be involved in the passive transport of calcium ions from the sarcoplasmic reticulum which may be regulated by the membrane potential.

[The effect of pH on the passive transport of Ca2+ by membranes of fragmented sarcoplasmic reticulum of skeletal muscles].

The initial rate of Ca2+ translocation in vesicular preparations of the sarcoplasmic reticulum membranes is shown to fall with a pH decrease to 6.0 or 5.0 and to rise with a pH change to 7.

[Catalytic properties of purified Ca2+,Mg2+-ATPase from the myometrium sarcolemma].

The catalytic properties of myometrium sarcolemmal Ca2+, Mg2(+)-ATPase purified from plasma membrane solubilizate by affinity chromatography on calmodulin-Sepharose were investigated. The enzyme isolated in the presence of azolectin revealed a calmodulin-independent affinity for Ca2+ (Km = 0.17 microM).

[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.

[Reconstruction of purified Ca2+,Mg2+-ATPase from the myometrium sarcolemma into liposomes and its catalytic properties].

The Ca2+, Mg2(+)-ATPase of the myometrium sarcolemma purified by the method of affinity chromatography on calmodulin sepharose is reconstituted into azolectin liposomes in the functionally active form by means of cholate dialysis. The ATPase-dependent accumulation of 45Ca is shown on the obtained model system. It makes up 95% of the total accumulation and may decrease to 43% under the effect of 0.

[Isolation and purification of Ca2+,Mg2+-ATPase from plasma membranes of the myometrium].

The preparation of the purified Ca2+, Mg2(+)-ATPase has been isolated from triton X-100 solubilizate of plasma membranes of the pig myometrium using the method of affinity chromatography on calmodulin-Sepharose 4B. The specific activity of the enzyme shows its 52-fold purification. The enzymic preparation practically has no Mg2(+)-ATPase activity.

[Calcium transport in endoplasmic reticulum of the rat liver during lipid peroxidation].

Some parameters of calcium transport in rat liver microsomes under conditions of lipoperoxidation activation modelled by antioxidant deficiency (AOD) were studied. This process was shown to be associated with a sharp stimulation of NADPH- and ascorbate-dependent lipid peroxidation in hepatocyte endoplasmic reticulum. The activation of lipid peroxidation was accompanied by disturbances in the kinetic properties of Ca2(+)-ATPase.

[The effect of ionizing radiation on the structure of the hydrophobic fragment of Ca-ATPase in skeletal muscle sarcoplasmic reticulum].

Early (1 and 24 h) after X-irradiation with a dose of 0.21 C/kg changes occurred in the acceptability of the polypeptide chain parts of sarcoplasmic reticulum Ca-ATPase for the effect of trypsin. The analysis of the results of studying the structural and functional properties of a hydrophobic fragment of this enzyme in the control and after irradiation permitted to define the part of the Ca-ATPase polypeptide chain that provided ion selectivity of the fragment.

[A mechanism of passive transport of Ca2+ in muscle sarcoplasmic reticulum].

Basing on the data available in literature and authors' investigations the mechanism of local alkalization of the myoplasm by proton efflux attended by Ca2+ influx is mic reticulum and may be the main link in the process of electrochemical coupling in the skeletal and cardiac muscle cells. Experimental evidence for participation of Ca2(+)-ATPase in the passive transport of calcium through sarcoplasmic membrane is given.

[The effect of Ca2+-phospholipid dependent phosphorylation on passive calcium transport in the myocardial sarcolemma].

Protein kinase C in vesicular preparations of the myocardium sarcolemma is shown to phosphorylate proteins with the molecular weight of 250, 140, 67, 58, 24 and 11 kD. The exogenic protein kinase C catalyzed phosphorylation of the sarcolemma preparations lowers the initial rate of the passive calcium transport from 0.56 down to 0.

[ATP-dependent transport of calcium in the myocardial sarcoplasmic reticulum during adaptation to muscular activities].

Two-fold increase in Ca2+-transport properties of Ca2+-pump was detected in myocardial sarcoplasmic reticulum (SR) during adaptation of animals to muscular activity (training by means of running on treadmill within 6 weeks, with gradual increase in duration and intensity). Besides, the rate of SR membranes phosphorylation via cAMP-dependent protein kinase was increased 1.3-fold.

[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.

[Intracellular Ca2+ homeostasis in the smooth muscle and functional role of calcium pump in the sarcolemma].

It has been found that Ca-pump of the smooth muscle sarcolemma has much greater affinity to Ca2+ (Km = 0.5 M) than the system Na-Ca2+ of the exchanger (Km = 40-60 M). The maximal rate of Mg2+, ATP-dependent translocation of Ca2+ is 2-3 times higher than that of Na-dependent.

[The role of Ca2+-ATpase and its hydrophobic component in the release of Ca2+ from skeletal muscle sarcoplasmic reticulum].

The Ca2+ permeability of proteoliposomes containing Ca2+-ATPase of sarcoplasmic reticulum and its hydrophobic fragment was investigated, using the method of synthetic penetrant ions and the radioisotopic method. The former method was used to determine the diffusional membrane potential formed by Ca2+ concentration gradient. It was demonstrated that Ca2+-ATPase, whose active center is oriented outside, has and asymmetric conductivity, i.

[cAMP-dependent phosphorylation inhibits potential-dependent passive transport of Ca2+ in myometrial sarcolemma vesicles].

It is established that Ca2+ transport from the predominantly inverted vesicles of pig myometrium sarcolemma depends on the value of the membrane potential which is created on vesicles by the K+-valinomycin system. It is shown that variations in the membrane potential from -60 to +30 mV cause acceleration of the calcium transport from the vesicles, the maximal transport being observed at delta psi from 0 up to +30 mV. The endogenic and exogenic cAMP-dependent phosphorylation of plasma membrane proteins inhibits the passive transport of calcium at all the membrane potential values studied.

[The channel function of the hydrophobic fragment of Ca ATPase in the sarcoplasmic reticulum of rabbit skeletal muscles in the early period after x-ray radiation exposure].

At early times (1 and 24 h) following local single exposure of rabbit hindlimbs to 0.21 C/kg X-radiation Ca ATPase was isolated from sarcoplasmic reticulum of skeletal muscles and inserted in liposomes the treatment of which with trypsin resulted in the formation of proteoliposomes with a Ca ATPase hydrophobic fragment (Mr 45-50 kDa). It was shown that X-radiation increased the permeability of univalent and bivalent cations through a channel formed by the hydrophobic fragment of Ca ATPase and diminished ion selectivity of this channel.

[ATP-dependent transport of Ca2+ in myocardium sarcolemma vesicles and its activation by phorbol esters].

Highly purified pig myocardium sarcolemma vesicles possess the Ca2+,Mg2+-ATPase activity (4.1 mumol Pi/mg protein/hour) and induce the ATP-dependent accumulation of 45Ca2+ (6.0 nmol/mg protein/min).