Alpha-Adrenergic Stimulation of Phosphatidylinositol Synthesis in Human Platelets as an Alpha-2 Effect Secondary to Platelet Aggregation
✍ Scribed by Michael A. Wallace; Kailash C. Agarwal; J. Adolfo Garcia-Sainz; John N. Fain
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 469 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
Epinephrine and adenosine diphosphate (ADP) stimulated ^3^H‐glycerol uptake into phosphatidylinositol of human platelets. Yohimbine, an alpha‐2 adrenoceptor antagonist, markedly reduced epinephrine‐stimulated ^3^H‐glycerol uptake into phosphatidylinositol; while prazosin, an alpha‐1 antagonist, was without effect. Likewise, yohimbine, but not prazosin, blocked epinephrine‐induced platelet aggregation. Furthermore, clonidine, a specific agonist for alpha‐2 adrenoceptors, stimulated incorporation of‐^3^H‐glycerol into phosphatidylinositol and promoted platelet aggregation in the presence of low concentrations of ADP. These studies indicate that the effects of epinephrine on platelet aggregation and phosphatidylinositol synthesis are mediated through alpha‐2 adrenoceptors. Further, since the stimulation of phosphatidylinositol synthesis seen with epinephrine was also observed with ADP, this suggests that the increased ^3^H‐glycerol labeling is an indirect result of platelet aggregation.