Biomedical subjects

V Sabanov

Publications and source records attributed to V Sabanov.

3 recordsLinked to original sources

PubMed2001

Cell cycle-related changes in regulatory volume decrease and volume-sensitive chloride conductance in mouse fibroblasts.

Cell cycle-related changes in the ability to regulate cell volume following hyposmotic swelling were studied in mouse fibroblasts using videomicroscopy and the whole-cell patch clamp technique. Regulatory volume decrease (RVD) and volume-sensitive Cl- conductance (G(Cl,vol)) were measured: (1) in proliferating cells of different sizes; (2) in cells arrested in defined phases of the cell cycle (G1, G1/S, S, and M phases) using mevastatin, mimosine, hydroxyurea, aphidicolin, cytosine beta-D-arabinofuranoside, and taxol; and (3) in serum-starved cells (G(0) state). Cells in all groups were able to undergo RVD, although the cells approaching mitosis (i.e., the largest cells in proliferating cultures and the taxol-treated cells) had the lowest rates of shrinkage during RVD. In agreement with this finding, the density of G(Cl,vol) was stable in proliferating and cell cycle-arrested cells for most of the cell cycle, with the exception of the cells approaching mitosis and the new daughter cells where the density was decreased to half. The impairment of RVD was greatest in serum-starved cells which also had the lowest density of G(Cl,vol). We conclude that proliferating cells maintain an ability to recover from osmotic swelling as they progress through the cell cycle, although this ability may be compromised during mitosis.

Animals↗

PubMed2000

Dual role of ATP in supporting volume-regulated chloride channels in mouse fibroblasts.

The effects of inhibitors of protein tyrosine kinases (PTKs) on the Cl(-) current (I(Cl(vol))) through volume-regulated anion/chloride (VRAC) channels whilst manipulating cellular ATP have been studied in mouse fibroblasts using the whole-cell patch clamp technique. Removal of ATP from the pipette-filling solution prevented activation of the current during osmotic cell swelling and when the volume of patched cells was increased by the application of positive pressure through the patch pipette to achieve rates exceeding 100%/min. Equimolar substitution of ATP in the pipette solution with its non-hydrolyzable analogs, adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS) or adenylyl-(beta,gamma-methylene)-diphosphonate (AMP-PCP), not only supported activation of the current but also maintained its amplitude. The PTK inhibitors, tyrphostins A25, B46, 3-amino-2,4-dicyano-5-(4-hydroxyphenyl)penta-2,4-dienonitrile++ + and genistein (all at 100 microM), inhibited I(Cl(vol)) in a time-dependent manner. Tyrphostin A1, which does not inhibit PTK activity, did not affect the current amplitude. The PTK inhibitors also inhibited I(Cl(vol)) under conditions where ATP in the pipette was substituted with ATPgammaS or AMP-PCP. We conclude that in mouse fibroblasts ATP has a dual role in the regulation of the current: it is required for protein phosphorylation to keep VRAC channels operational and, through non-hydrolytic binding, determines the magnitude of I(Cl(vol)). We also suggest that tyrosine-specific protein kinases and phosphatases exhibit an interdependent involvement in the regulation of VRAC channels.

Adenosine Triphosphate↗

PubMed1995

Chloride channels in brown adipocyte plasma membranes: candidates for mediation of alpha 1-adrenergic depolarization?

The presence of plasma membrane Cl- channels was investigated in brown-fat cells differentiated in culture. Single channel activity was followed by the patch-clamp technique, with an NMDG+ Cl- pipette solution and a NaCl bath solution. Only rarely was putative Cl- channel activity encountered in the cell-attached mode. However, after excision, ion channel activity of two types was observed in inside-out patches: one type represented the earlier observed non-selective cation channel, and one a putative Cl- channel, with the following characteristics: practically non-rectifying current-voltage relationship with a conductance of approximately 50 pS and a reversal potential of approximately 0 in symmetrical Cl- solutions, voltage dependent channel activity (Po approached 0.5 at positive holding potentials), and rapid flickering activity in the open state. It is discussed whether this Cl- channel may be responsible for the initial depolarization phase observed after alpha 1-adrenergic stimulation of brown-fat cells.

Adipose Tissue, Brown↗