[Effect of neuroendocrine cell differentiation of the human prostatic neoplasm cell line LNCaP on the characteristics of volume-sensitive chloride content]. / Vplyv neiroendokrynnoho dyferentsiiuvannia klityn raku prostaty liudyny liniï LNCaP na kharakterystyky ob'iemchutlyvoho khlornoho strumu.

By means of patch-clamp technique we examined changes in volume-regulated chloride current (ICl,swell) at neuroendocrine differentiation of androgen-dependent LNCaP prostate cancer cells. In those cells with neuroendocrine differentiation resulted from an increase in the intracellular cAMP, ICl,swell became much faster in response to applying external hypotonic solution and cell swelling. Changes in final rectification and voltage-dependent inactivation were not detected, as compared to the control cells. The differentiation also diminished ICl,swell blockade by Ca2+ transported via store-operated channels (SOC). On the base of our data we suggest that potentiation of the current at neuroendocrine differentiation, at least in part, resulted from a decrease in an inhibitory effect of Ca2+, transported into a cell through SOC, on volume-sensitive chloride current. Accelerated current in those cells might be induced by cytoskeleton rearrangement at the neuron-like growth.

[Volume-sensitive anion conductivity in a human prostatic carcinoma cell line]. / Ob'iemchutlyva anionna providnist' u klitynnii liniï kartsynomy prostaty liudyny.

For the first time membrane anion current activated in response to the cell swelling following exposure to hypotonic solution has been found in human prostate carcinoma cell line LNCaP. The development of hypotonicity-evoked current required 5 to 10 min to the maximum and was almost completely reversible upon return to the solution with normal osmolarity. Not absolute selectivity for Cl- ions of the respective cell volume-sensitive channels has been shown.

Potassium conductance in the androgen-sensitive prostate cancer cell line, LNCaP: involvement in cell proliferation.

BACKGROUND: Very little is known about the expression of ion channels in prostate cells (both normal and malignant), and their possible role in physiological and pathological functions. We therefore studied ion conductances and their role in the proliferation of LNCaP cells, an androgen-sensitive human prostate cancer cell line. METHODS: We applied patch-clamp recording techniques for electrophysiological studies, and 3H-thymidine incorporation and protein content assays for cell growth studies. RESULTS: Only one type of voltage-dependent ion conductance, a potassium K+ conductance, was identified. This current, which was depressed by a rise in intracellular Ca2+, had a high sensitivity to tetraethylammonium (TEA) (with half-block at 2 mM) and was also inhibited by 2 nM alpha-dendrotoxin (DTX) and 20 nM mast-cell degranulating peptide (MCDP). K+ channel inhibitors inhibited [3H]thymidine incorporation and protein content, in a dose-dependent fashion, indicating that K+ channels are involved in cell growth. CONCLUSIONS: We conclude from our findings that the human cancer prostate cell line LNCaP has a new type of K+ channel, likely to play an essential role in the physiology of these cells and, more specifically, in cell proliferation.

Role of tyrosine phosphorylation in potassium channel activation. Functional association with prolactin receptor and JAK2 tyrosine kinase.

Chinese hamster ovary (CHO) cells, stably transfected with the long form of the prolactin (PRL) receptor (PRL-R) cDNA, were used for PRL-R signal transduction studies. Patch-clamp technique in whole cell and cell-free configurations were employed. Exposure of transfected CHO cells to 5 nM PRL led to the increase of Ca(2+)- and voltage-dependent K+ channel (KCa) activity. The effect was direct as it was observed also in excised patch experiments. A series of tyrosine kinase inhibitors was studied to investigate the possible involvement of protein tyrosine kinases in KCa functioning and its stimulation by PRL. Genistein, lavendustin A, and herbimycin A decreased in a concentration and time-dependent manner the amplitude of the KCa current in whole cell and the open probability of KCa channels in cell-free experiments. The subsequent application of PRL was ineffective. The protein tyrosine phosphatase inhibitor orthovanadate (1 mM) stimulated KCa channel activity in excised patches, indicating that channels can be modulated in opposite directions by protein tyrosine kinase and protein tyrosine phosphatase. Moreover, in whole cell experiments as well as in excised patch recordings, anti-JAK2 tyrosine kinase antibody decreased the KCa conductance and the open probability of the KCa channels. Subsequent application of PRL was no longer able to stimulate KCa conductance. Immunoblotting studies using the same anti-JAK2 antibody, revealed the constitutive association of JAK2 kinase with PRL-R. Preincubation of anti-JAK2 antibody with the JAK2 Immunizing Peptide abolished the effects observed using anti-JAK2 antibody alone in both electrophysiological and immunoblotting studies. We conclude from these findings that these KCa channels are regulated through tyrosine phosphorylation/dephosphorylation; JAK2 tyrosine kinase, constitutively associated with PRL-R, is implicated in PRL stimulation of KCa channels.

[Effects of short-term application of glutamate-containing solution on isolated rat hippocampal neurons]. / Effekty kratkovremennoi applikatsii glutamatsoderzhashchego rastvora na izolirovannye neirony gippokampa krys.

The "concentration clamp" technique has been modified to realize fast and short-term application of a transmitter to whole neuron followed by its fast washout. Prolonged glutamate application evoked activation of the desensitized current. The application time was shortened to intervals when the washout corresponded to unfinished desensitization of the current. Shortening of the glutamate application term to some milliseconds resulted in arising of fast currents which maximal amplitude appreciably exceeded that of currents evoked by prolonged glutamate application. The role of both components under real synaptic conditions is discussed.

[Study of the recovery rate of non-NMDA desensitized receptors of hippocampal neurons using paired and rhythmic application of glutamate]. / Issledovanie vykhoda neNMDA-retseptorov neironov gippokampa iz sostoianiia desensitizatsii s ispol'zovaniem parnoi i ritmicheskoi applikatsii glutamata.

The new technique has been used to realize paired short-term application of glutamate to whole dialyzed neuron. Desensitization of receptors via first application of glutamate resulted in incomplete recovery of the current evoked by the second application if interval between both applications was less than 160 ms. The recovery time constant of the current was found to be 44 ms at single exponential approximation. It is close to the mean desensitization time constant of the current evoked by single prolonged application of glutamate. Rhythmic application of glutamate resulted in a rapid fall of the mean current amplitude at frequencies over 10 Hz. Data obtained by the authors confirm the known concept of desensitization of non-NMDA receptors as a relatively slow conformation of the receptor-channel complex.

[Features of the effect of leukotriene LTC4 and the blocker of its biosynthesis BW755C on the contractile capability of smooth muscles and the functioning of potential-dependent calcium channels of the nerve cell]. / Osobennosti vliianiia leikotriena LTC4 i blokatora ego biosinteza BW755C na sokratitel'nuiu sposobnost' gladkikh myshts i funktsionirovanie potentsialozavisimykh kal'tsievykh kanalov nervnoi kletki.

The effect of LTC4, a synthetic leukotriene, and of BW 755C, a blocker of its biosynthesis on the functioning of Ca-channels in the membrane of snail neurons and on the contractile activity of rat uterus muscles in late terms of pregnancy was studied by means of intracellular dialysis and spontaneous contractility recording techniques. It was found that the 10(-7) mol/l of LTC4 stimulated the contractile function of the rat uterus and activated effectively the Ca-conductance in the somatic membrane of the nervous cell. The action of BW 755C was similar to that of leukotriene on Ca-conductance; in addition BW 755C produced transient activation of contractions of the rat uterus followed by a complete suppression of smooth muscle contractions. Possible mechanisms of the effects described were discussed.

[Action of the leukotriene LTC4 on the calcium channels of the somatic membrane of the nerve cell and tone of smooth muscle organs]. / Deistvie leikotriena LTC4 na kal'tsievye kanaly somaticheskoi membrany nervnoi kletki i tonus gladkomyshechnykh organov.

Effects of synthetic leukotriene LTC4 on the internally perfused voltage-clamped snail neurons as well as on the electrical and mechanical activities of the stomach smooth muscle cells were studied. It was found that LTC4 increased calcium inward current in the soma membrane of a cell by activation of both voltage and receptor operated Ca-channels. LTC4 was effective only from outside but not from inside of the membrane which indicated that there was a receptor for leukotrienes in the neuronal membrane.

[Effect of the lipoxygenase blockader BW755C on calcium currents in the nerve cell membrane of the snail and on the contractile responses of the ureteral smooth-muscle fibers in the guinea pig]. / Vliianie blokatora lipooksigenazy BW755C na kal'tsievye toki v membrane nervnoi kletki ulitki i sokratitel'nye otvety gladkomyshechnykh volokon mochetochnika morskoi svinki.

Lipoxygenase blocker BW755C has been studied for its effect on calcium inward current in intracellularly perfused voltage clamped and contraction of guinea-pig ureter smooth muscle. BW755C increased the Ca inward current in somatic membrane and inhibited contraction of the smooth muscle evoked by high-potassium solution. It is suggested that the effects observed are related to the changes in the level of cyclic nucleotides in cytoplasm due to the action of the final products of lypoxygenase breakdown of fatty acids from the cell membrane.

Effects of morphine and opioid peptides on sensitivity to acetylcholine of dialysed snail neurons.

The effects of intracellular and extracellular applications of morphine (in concentrations from 10(-3) to 10(-5) M), leucine-enkephalin and methionine-enkephalin (10(-6) to 10(-8) M) were studied in unidentified acetylcholine-sensitive dialysed neurons of a snail under voltage clamp. Morphine produced inward membrane currents, while enkephalins did not. Both morphine and enkephalins altered the effect of acetylcholine on postsynaptic acetylcholine receptors; intracellular application of these substances being much more effective than extracellular application. This suggested that opioid peptides take part in the regulation of cholinergic synaptic transmission.

[Modulation of the functioning of muscarinic and nicotinic cholinoreceptors of dialyzed snail neurons by opiate peptides and morphine]. / Moduliatsiia funktsionirovaniia muskarinovykh i nikotinovykh kholinoretseptorow dializirovannykh neironov ulitki opiatnymi peptidami i morfinom.

A modulating effect of morphine and enkephalins on the functioning of muscarinic and nicotinic cholinoreceptors of the snail neurons was studied by intracellular dialysis technique under voltage clamp conditions. It is found that different effects of these agents on acetylcholine responses of isolated neurons are due to their selective modulating influence on M- and N-cholinoreceptors.

[Effect of morphine on dialyzed Helix pomatia neurons]. / Vliianie morfina na dializirovannye neirony vinogradnoi ulitki.

Intra- and extracellular influence of morphine was studied on isolated snail neurons by the method of intracellular dialysis under conditions of membrane potential clamp. It is found that morphine induces an inward current in all the investigated cells, it also changes the sensitiveness of the membrane to acetylcholine depending on the type of cell under investigation. It is suggested that such influence in normally functioning cells may be realized by endogenic peptides-analgetics.

[Excitatory effect of atropine on frog sympathetic ganglia]. / Vozbuzhdaiushchee deistvie atropina na neirony simpaticheskikh gangliev liagushki.

Depolarization accompanied by an increase in the membrane conductance produced by atropine was studied in frog sympathetic ganglion neurons after activation of the receptors with different cholinomimetics. Atropine perfusion caused excitatory effects if perfusion with acetylcholine or with a mixture of suberildicholine and 5-methylfurmethide has been performed beforehand, i.e. an activation of both nicotinic and muscarinic receptors has taken place. After preceeding activation of nicotinic receptor with suberildicholine or muscarinic receptor with 5-methylfurmethide atropine caused no changes in electric properties of the membrane. It is supposed that atropine, acting on receptors changed after the action of agonists, can evoke their activation.

[Depolarization of primary afferents during fictitious scratching of thalamic cats]. / Depoliarizatsiia pervichnykh afferentov pri fiktivnom chesanii talamicheskikh koshek.

The cord dorsum and dorsal root potentials were recorded during fictious scratching in L6 segment of the thalamic cats. It is shown that primary afferent depolrization (PAD) can be modulated by the central generator of scratching. In some afferent fibres antidromic spikes appear on the top of PAD-waves. Antidromic spikes can be also evoked in the period of "rest" by mechanical stimulation of hindlimb receptors. It is supposed that PAD and resulting antidromic spikes which appear during real scratching may effectively control the level of afferent inflow to the spinal neurons.