Abstract |
BAY y 5959 is a dihydropyridine derivative with positive inotropic actions mediated by a direct increase in intracellular calcium. We characterized the direct myocardial actions of this new agent in hearts isolated from seven normal dogs and from five dogs with repeated coronary microembolization-induced heart failure. Inotropic actions of BAY y 5959 were accompanied by little effect on duration of contraction and by prolongation of the monophasic action potential (MAP); in contrast, isoproterenol decreased contraction and MAP durations. Whereas inotropic responsiveness to isoproterenol was blunted in embolized hearts, these actions of BAY y 5959 were relatively preserved in the heart failure state. Isoproterenol increased heart rate, whereas BAY y 5959 had little effect. Changes in coronary vascular resistance also decreased similarly for isoproterenol and BAY y 5959. Finally, for comparable inotropy, increases in myocardial oxygen consumption were similar for isoproterenol and for BAY y 5959. In summary, preserved inotropic responsiveness and lack of positive chronotropic actions are two clinically favorable features of this type of inotropic agents compared with a typical beta-adrenergic agonist.
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Authors | K Todaka, J Wang, G H Yi, A Gu, S M Zhu, H Zhang, D Burkhoff |
Journal | The American journal of physiology
(Am J Physiol)
Vol. 274
Issue 5
Pg. H1560-8
(05 1998)
ISSN: 0002-9513 [Print] United States |
PMID | 9612364
(Publication Type: Journal Article)
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Chemical References |
- BAY y 5959
- Cardiotonic Agents
- Dihydropyridines
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Topics |
- Animals
- Cardiotonic Agents
(pharmacology)
- Dihydropyridines
(pharmacology)
- Dogs
- Heart
(drug effects, physiology)
- Heart Failure
(metabolism, physiopathology)
- Heart Rate
(drug effects)
- Hemodynamics
(drug effects)
- Myocardial Contraction
(drug effects)
- Myocardium
(metabolism)
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