Gadolinium selectively blocks a component of calcium current in rodent neuroblastoma x glioma hybrid (NG108-15) cells

J Physiol. 1988 Apr;398:33-47. doi: 10.1113/jphysiol.1988.sp017027.

Abstract

1. The effect of the lanthanide cation Gd3+ on voltage-dependent calcium currents in neuroblastoma x glioma (NG108-15) cells has been studied using a whole-cell clamp technique. 2. Gd3+ reduced the amplitude of calcium currents. The amount of inhibition produced by Gd3+ was concentration dependent between about 0.5 and 5 microM and reached a maximum at about 10-20 microM. 3. A proportion of the total calcium current was resistant to blockade by Gd3+. 4. Gd3+-resistant calcium current consisted of two components: a rapidly inactivating, 'fast' component which was activated at potentials more positive than about -45 mV, and a long-lasting, 'slow' component which was activated at potentials more positive than about -10 mV. 5. It was possible to isolate the slow component, in the presence of Gd3+, by selectively inactivating the fast component with a brief depolarizing pre-pulse. The fast and slow components of current probably reflect the activity of two subpopulations of calcium channels which are resistant to block by Gd3+. 6. In control conditions inactivation of calcium current could be described by the sum of a fast (tau congruent to 40 ms at +10 mV) and a slow (tau congruent to 800 ms at +10 mV) exponential decay plus a constant. Gd3+ selectively blocked the slowly decaying current. 7. The current blocked by Gd3+ was activated at potentials more positive than about -35 mV and decayed monoexponentially (tau congruent to 800 ms at +10 mV). 8. It is concluded that under the experimental conditions used in the present study calcium currents recorded in NG108-15 cells are made up of at least three components which reflect the activity of three distinct subpopulations of calcium channels, one of which is selectively blocked by Gd3+.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / physiology
  • Calcium Channel Blockers / pharmacology*
  • Electrophysiology
  • Gadolinium / pharmacology*
  • Glioma / physiopathology*
  • Hybrid Cells / drug effects
  • Hybrid Cells / physiology
  • Neuroblastoma / physiopathology*
  • Rats
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / physiology

Substances

  • Calcium Channel Blockers
  • Gadolinium
  • Calcium