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Cyclic AMP-phosphodiesterase IIIA1 inhibitors decrease cytosolic Ca2+ concentration and increase the Ca2+ content of
P Roevens1, D de Chaffoy de Courcelles
1Department of Biochemistry II, Janssen Research Foundation, Beerse, Belgium.
Biochemical Pharmacology
|June 9, 1993
Summary
Cyclic AMP-phosphodiesterase (cAMP-PDE) inhibitors like milrinone and R 80 122 reduce resting platelet cytosolic Ca2+ while increasing intracellular Ca2+ stores. This highlights cAMP's role in calcium homeostasis.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Calcium (Ca2+) homeostasis is crucial for platelet function.
- Cyclic AMP (cAMP) plays a role in regulating intracellular Ca2+ levels.
- Cyclic AMP-phosphodiesterase (cAMP-PDE) inhibitors modulate cAMP levels.
Purpose of the Study:
- To investigate the effects of cAMP-PDE inhibitors on Ca2+ homeostasis in human platelets.
- To determine how these inhibitors alter cytosolic and intracellular Ca2+ concentrations.
Main Methods:
- Utilized quin-2 and chlorotetracycline (CTC) to measure cytosolic Ca2+.
- Quantified Ca2+ accumulation in intracellular storage sites.
- Tested therapeutic concentrations (1 microM) of milrinone, R 80 122, and enoximone.
Main Results:
- Milrinone and R 80 122 (at 1 microM) decreased resting platelet cytosolic Ca2+.
- The same inhibitors increased Ca2+ content within intracellular platelet stores.
- Enoximone did not exhibit these effects at the tested concentrations.
Conclusions:
- cAMP-PDE inhibitors influence Ca2+ distribution in human platelets.
- Findings support the proposed mechanism of cAMP-PDE inhibitors on cardiomyocyte function.
- These results underscore the significance of cAMP in regulating Ca2+ homeostasis.