Bradykinin-evoked non-specific cationic current in neuroblastoma-glioma hybrid (NG108-15) cells and its down-regulation through differentiation

Brain Res. 1994 Sep 19;657(1-2):202-6. doi: 10.1016/0006-8993(94)90968-7.

Abstract

Effects of bradykinin (BK) on the membrane conductance and level of cytoplasmic free Ca2+ in undifferentiated and differentiated neuroblastoma-glioma hybrid (NG108-15) cells were studied using the nystatin-perforated patch-clamp technique and fura-2 fluorometry. Under voltage clamp at -20 mV, undifferentiated cells responded to BK at > 10(-9) M, producing a biphasic current composed of an apamin-sensitive Ca(2+)-activated K+ outward current and non-specific cationic inward current. Both current components corresponding to a biphasic elevation of [Ca2+]i were completely prevented by an intracellular perfusion with EGTA (1 mM) under conventional whole cell recording condition. Undifferentiated cells revealed almost no voltage sensitive Ca2+ current. In NG108-15 cells differentiated with 8-Br-cyclic AMP (1 mM) or rolipram (1 mM), an inhibitor of type IV phosphodiesterase, BK concentration required for the non-specific cationic current with amplitude of > 100 pA was much greater than that of undifferentiated cells. This suggests that the differentiated cells decreased BK-sensitivity in induction of the non-specific cationic current. The non-specific cationic channel is suggested to play roles as a source of Ca2+ entry in undifferentiated NG108-15 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bradykinin / pharmacology*
  • Calcium / metabolism*
  • Cell Differentiation / drug effects
  • Down-Regulation / drug effects
  • Glioma
  • Humans
  • Hybrid Cells / drug effects*
  • Ion Channels / drug effects*
  • Membrane Potentials / drug effects
  • Neuroblastoma
  • Patch-Clamp Techniques
  • Potassium / metabolism*
  • Sodium / metabolism*

Substances

  • Ion Channels
  • Sodium
  • Potassium
  • Bradykinin
  • Calcium