Cardiac Effects of Amrinone on Rabbit Papillary Muscle and Guinea Pig Langendorff Heart Preparations
| Autor: | G. Onuaguluchi, Ralph D. Tanz |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Male
Inotrope medicine.medical_specialty Langendorff heart Cardiotonic Agents Time Factors Refractory Period Electrophysiological Guinea Pigs Aminopyridines Stimulation In Vitro Techniques Pharmacology Amrinone Oxygen Consumption Heart Rate Coronary Circulation Internal medicine Heart rate medicine Animals Papillary muscle Dose-Response Relationship Drug Chemistry Papillary Muscles medicine.disease Myocardial Contraction Electric Stimulation medicine.anatomical_structure Bigeminy Cardiology Verapamil Female Rabbits Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | Journal of Cardiovascular Pharmacology. 3:1342-1358 |
| ISSN: | 0160-2446 |
| DOI: | 10.1097/00005344-198111000-00022 |
| Popis: | Amrinone (50-1,000 microgram/ml) produces a dose-dependent inotropic action on rabbit papillary muscle. The hypodynamic state following prolonged stimulation is prevented or abolished by amrinone, and contractile force remains significantly elevated over drug-free controls throughout the ensuing 3-h duration of exposure. In a concentration of 1 mg/ml, dysrhythmic phenomena occasionally appeared, e.g., bigeminy, automaticity, and elevated threshold to electrical stimulation. Bigeminy could be abolished either by increasing the external K+ concentration in the bathing media, or by raising the stimulating voltage. However, amrinone failed to alter the refractory period following 60 min of exposure. In isolated perfused guinea pig Langendorff heart preparations, amrinone (50 microgram/ml) significantly increased coronary flow, myocardial oxygen consumption (MVO2), cardiac work, and, during the period of peak activity, dP/dt. However, it had no significant effect on cardiac efficiency. And, as in the papillary muscle preparation, the effect of amrinone was easily reversed by perfusing the preparation with fresh (no-drug) media. Preliminary evidence shows that amrinone fails to reverse the negative inotropic action of verapamil as well as calcium-free media, although the effects on heart rate, coronary flow, and MVO2 were reversed. However, the higher the external calcium concentration, the greater was the level of contractile response achieved by amrinone. Thus, the mechanism of amrinone-induced augmentation appears to be dependent upon the availability of calcium. |
| Databáze: | OpenAIRE |
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