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Action-potential duration and contractility in canine cardiac tissues: action of inotropic drugs.
- Source :
-
General pharmacology [Gen Pharmacol] 1998 Sep; Vol. 31 (3), pp. 415-8. - Publication Year :
- 1998
-
Abstract
- 1. Inotropic and electrophysiologic effects of veratrine, vesnarinone, d-sotalol and tetraethylammonium (TEA) were compared. Action-potential duration (APD) and contractility were measured in isolated canine Purkinje fiber and ventricular trabecular muscle preparations by using standard microelectrode techniques. Each drug significantly increased APD and force development in either tissue. 2. Drug-induced increases in force development were normalized to increases in APD. The order of efficacy was found to be vesnarinone>veratrine>TEA in ventricular myocardium, whereas it was veratrine>>vesnarinone=d-sotalol=TEA in Purkinje fibers. 3. The force-APD relation was linear for all drugs in the concentrations used. 4. Simultaneous measurements of APD, force development and intracellular sodium ion activity (a(i)Na) in the presence of either veratrine or lidocaine indicated a linear relation between force development and changes in a(i)Na. 5. The relation between APD and force development was different in ventricular and Purkinje fiber preparations. Differences in the veratrine sensitivity of the force-APD relation observed between Purkinje and ventricular preparations suggest that a(i)Na-dependent changes in Na+/Ca2+ exchange may play a more important role in regulation of force generation in Purkinje fibers than in ventricular myocardium.
- Subjects :
- Animals
Dogs
Female
In Vitro Techniques
Male
Myocardium metabolism
Purkinje Fibers physiology
Pyrazines
Quinolines pharmacology
Sodium metabolism
Sotalol pharmacology
Tetraethylammonium pharmacology
Veratrine pharmacology
Action Potentials drug effects
Cardiotonic Agents pharmacology
Myocardial Contraction drug effects
Purkinje Fibers drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0306-3623
- Volume :
- 31
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- General pharmacology
- Publication Type :
- Academic Journal
- Accession number :
- 9703211
- Full Text :
- https://doi.org/10.1016/s0306-3623(98)00026-3