| RESEARCH PAPER
|Year : 1998 | Volume
| Issue : 1 | Page : 25-29
Calcium dependency of the positive inotropic effects of phosphodiesterase inhibitors on the amphibian and mammalian myocardium
AR Juvekar, RVSV Vadlamudi
Objective: To study the relationship of changing Ca2+levels, to the inotropic responses of amphibian and mammalian myocardium, to phosphodiesterase (PDE) Ill inhibitors, milrinone and trequinsin hydrochloride (HL725).
Methods: The inotropic effects of milrinone and HL725 were investigated, on the isolated perfused frog heart and the isolated electrically - paced guinea pig left atrium at different perfusate calcium levels.
Results: HL725 and milrinone produced a dose-dependent positive inotropy effect. The mammalian myocardium exhibited greater magnitude of positive inotropic response as compared to the isolated frog heart.
Conclusion: The responses to HL725 and milrinone are species specific; due to the inherent ultrastructural variations and the resultant changed intracellular Ca2+ mileu.
A R Juvekar
Source of Support: None, Conflict of Interest: None