Effect of capsaicin on membrane currents in cultured vascular smooth muscle cells of rat aorta

Eur J Pharmacol. 1995 Mar 16;292(3-4):321-8. doi: 10.1016/0926-6917(95)90039-x.

Abstract

The application of capsaicin (1 microM) produced a minor relaxant effect in endothelium-denuded rat aortae. However, capsaicin caused a greater relaxation of blood vessels precontracted with high K+ or phenylephrine. The effects of capsaicin on the ionic currents were also examined in A7r5 vascular smooth muscle cells. The tight-seal whole-cell voltage clamp technique was used. Capsaicin inhibited the Ba2+ inward current (IBa) through the voltage-dependent L-type Ca2+ channel in a concentration-dependent fashion, whereas calcitonin gene-related peptide and phenylephrine produced a minor increase in IBa. Capsaicin did not alter the overall shape of current-voltage relationship of IBa. However, capsaicin (3 microM) shifted the quasi-steady-state inactivation curve of IBa to more negative membrane potential by about 5 mV. These effects of capsaicin on IBa were reversible. In addition, capsaicin had inhibitory effects on voltage dependent K+ currents. These results suggest that inhibition of the voltage-dependent L-type Ca2+ channel is involved in the capsaicin-induced relaxation of the vascular smooth muscle, whereas capsaicin-induced inhibition of voltage-dependent K+ channels might produce an increase in cell excitability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta, Thoracic / cytology
  • Aorta, Thoracic / drug effects
  • Aorta, Thoracic / metabolism
  • Capsaicin / pharmacology*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Electrophysiology
  • Endothelium, Vascular / physiology
  • Ion Channels / drug effects
  • Ion Channels / metabolism*
  • Muscle Contraction / drug effects
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Wistar

Substances

  • Ion Channels
  • Capsaicin