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Voltage-gated T-type Ca2+ channels and heart failure
J P Clozel1, E A Ertel, S I Ertel
1Actelion Ltd, Innovation Center, Allschwil, Switzerland.
Proceedings of the Association of American Physicians
|October 16, 1999
Summary
T-type calcium channels are implicated in cardiac hypertrophy and arrhythmia. While T-type channel blockade showed promise in animal heart failure models, drug interactions halted human trials.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
Background:
- T-type calcium channels regulate vascular tone and cardiac automaticity.
- Upregulation of T-type channels in cardiac hypertrophy may promote arrhythmia.
- These channels influence cell proliferation and neurohormonal secretion, potentially impacting myocardial remodeling.
Purpose of the Study:
- To investigate the pathophysiological role of T-type calcium channels in heart failure.
- To evaluate the efficacy of T-type selective calcium channel blockers in heart failure models.
Main Methods:
- Utilized mibefradil, a potent T-type calcium channel antagonist.
- Tested mibefradil in experimental models of cardiac hypertrophy and heart failure, including the Pfeffer rat model.
- Compared mibefradil's effects to classic L-type calcium channel antagonists.
Main Results:
- Mibefradil demonstrated beneficial effects in multiple animal heart failure models.
- Unlike L-type antagonists, mibefradil did not induce negative inotropic effects or stimulate the neurohormonal system.
- Blockade of T-type channels with mibefradil improved survival rates in the Pfeffer rat model.
Conclusions:
- T-type calcium channels play a significant role in the pathophysiology of heart failure.
- Selective T-type channel blockade holds therapeutic potential for heart failure, as evidenced by animal studies.
- Drug interactions in humans led to the withdrawal of mibefradil, preventing definitive clinical efficacy assessment for heart failure treatment.