[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.

[The influence of extracellular pH on volume-activated chloride current in the prostate cancer epithelial cells]. / Vpliv zovnishn'oklitynnoho pH na ob'iemaktivovanyi khlornyi strum v epitelial'nykh klitynakh kartsynomy prostaty.

The influence of extracellular pH on characteristics of volume-activated chloride current, ICl,swell, in the human prostate cancer epithelial cell line, LNCaP, was studied using the patch-clamp technique. Acidification of the extracellular hypotonic solution used to develop the current shortened the temporal parameters of ICl,swell development and reduced its maximal density. Sudden shifts of the pH towards acidification caused fast, transient potentiation of the current followed by its sustained inhibition. Voltage-dependent inactivation of ICl,swell was the most pronounced in the narrow range of pH = 6-7. Based on the analysis of our data we hypothesize that volume-regulated anion channels underlying ICl,swell possess in their structure at least two pH-sensitive molecular groups with similar pK = 6, titration of which modulates the current amplitude and two additional proton-sensitive groups that determine channel's inactivation.

[Effect of intracellular trypsin on characteristics of voltage-dependent inactivation of chloride currents in prostatic cancer cells]. / Vplyv vnutrishn'oklitynnoho vvedennia trypsynu na kharaterystyky potentsialzalezhnoï inaktyvatsiï khlornoho strumu v klitynakh raku prostaty.

By means of the patch-clamp technique we have studied the effects of intracellular applied trypsin, a known modulator of membrane channel function, on the properties of the Cl- current induced by hypotonicity-obliged cell swelling (ICl, swell) in human prostate cancer epithelial cells, LNCaP. Intracellular infusion of 1 mg/ml of trypsin into LNCaP cells via the patch pipette shortened the delay for the onset and the time of development of ICl, swell in response to hypotonicity as well as accelerated the rate of current diminution following the return to isotonic conditions. The maximal density of ICl, swell in the presence of intracellular trypsin was 2-fold higher while the current voltage-dependent inactivation at high depolarizing potentials was virtually eliminated. Intracellular co-application of the trypsin inhibitor together with trypsin abolished all effects of trypsin. We conclude that VRACs share a great degree of functional and structural homology to voltage-gated Na+, K+ and Cl- channels by having intracellular inactivation domain subjected to proteolytic cleavage that function in conformity with "ball-and-chain" inactivation model.