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Interaction between Ca(2+) channel blockers and isoproterenol on L-type Ca(2+) current in canine ventricular

V Farkas1, N Szentandrássy, L Bárándi

  • 1Department of Dentistry, University of Debrecen, Debrecen, Hungary.

Acta Physiologica (Oxford, England)
|April 24, 2012
PubMed
Abstract

Insights

Isoproterenol enhances L-type calcium current, but its effect is blocked by inorganic agents (CoCl2, MnCl2), not organic calcium channel blockers. This highlights differing drug interactions under sympathetic stimulation.

Area of Science:

  • Cardiovascular Physiology
  • Pharmacology
  • Cellular Electrophysiology

Background:

  • Calcium (Ca2+) channels are crucial for cardiac function.
  • Isoproterenol is a beta-adrenergic agonist that modulates Ca2+ current.
  • Calcium channel blockers are used to treat cardiovascular diseases.

Purpose of the Study:

  • To investigate the antagonistic interactions between calcium channel blockers and isoproterenol.
  • To determine the effect of various Ca2+ channel blockers on L-type Ca2+ current amplitude in canine ventricular cells.

Main Methods:

  • Utilized the whole-cell patch clamp technique.
  • Studied the impact of isoproterenol on Ca2+ current.
  • Examined effects in the presence and absence of nifedipine, nisoldipine, diltiazem, verapamil, cobalt chloride (CoCl2), and manganese chloride (MnCl2).

Main Results:

  • Organic Ca2+ channel blockers (nifedipine, nisoldipine, diltiazem, verapamil) and inorganic blockers (CoCl2, MnCl2) all caused significant blockade of Ca2+ current.
  • Isoproterenol alone increased Ca2+ current amplitude.
  • Isoproterenol enhanced Ca2+ current in the presence of organic blockers but not inorganic blockers (CoCl2, MnCl2).

Conclusions:

  • Isoproterenol's action differs depending on the type of Ca2+ channel blocker.
  • Inorganic blockers (CoCl2, MnCl2) fully prevented isoproterenol's effect on Ca2+ current.
  • Organic blockers did not prevent isoproterenol's effect, suggesting different interaction mechanisms relevant for clinical and experimental evaluations during sympathetic activation.

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