Nitrendipine inhibition of calcium current in rat vascular muscle cells

Kent Hermsmeyer, Michael Sturek, Nancy J. Rusch

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

The effect of nitrendipine on spontaneous contraction frequency and Ca2+ currents was studied in spontaneously active rat azygos venous cells in primary culture. Nitrendipine reduced the frequency of contraction in a concentration-dependent manner, with 50% inhibition (IC50) at approximately 10-7 M. In similar cells using the whole-cell voltage-clamp technique, nitrendipine (10-7 M) reduced the peak magnitude of the longer lasting, high-threshold (L) Ca2+ channel current by 52 ± 6%, while the transient, low-threshold (T) Ca2+ channel current was unaffected. As estimated from the current-voltage inactivation relationship, the dissociation constant (Kd) for nitrendipine binding to the resting state of Ca2+ channels was 108 nM for the L channel and ≥2 μM for the T channel. This high-affinity binding of the dihydropyridine to the resting state of the L channel in vascular muscle contrasts with the lower-affinity binding reported in cardiac muscle. Thus, nitrendipine may inhibit spontaneous activity in vascular muscle cells at least partly by blocking Ca2+ current through L channels.

Original languageEnglish (US)
Pages (from-to)S100-S103
JournalJournal of cardiovascular pharmacology
Volume12
Issue number5
DOIs
StatePublished - 1988

Keywords

  • Azygos vein
  • Calcium antagonist
  • Calcium channel blockers
  • Calcium channels
  • Dihydropyridine
  • Nitrendipine
  • Pacemaker currents
  • Spontaneous activity
  • Vascular smooth muscle

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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