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Title: Adenylate cyclase activation determines the effect of thromboxane synthase inhibitors on platelet aggregation in vitro. Comparison of platelets from responders and nonresponders
Authors: Gresele, P ×
Blockmans, Daniel Engelbert
Deckmyn, Hans
Vermylen, Jozef #
Issue Date: Aug-1988
Series Title: Journal of Pharmacology and Experimental Therapeutics vol:246 issue:1 pages:301-7
Abstract: The effect of five thromboxane-synthase inhibitors (UK-37248, UK-38485, UK-34787, CGS-13080 and OKY-1581) on arachidonic acid-induced platelet aggregation has been studied in vitro on platelets from 30 different healthy volunteers. The sensitivity of their platelets to adenylate cyclase stimulators or to dibutyryl cyclic AMP has been evaluated contemporarily. In 4 of the 30 volunteers tested no inhibition of platelet aggregation was obtained with any of the five thromboxane synthase inhibitors: these subjects were defined nonresponders; in 13 volunteers inhibition was observed with all the five drugs (responders). Significantly higher amounts of prostaglandin (PG)D2, prostacyclin and adenosine were required to suppress arachidonic acid-induced aggregation of platelets from nonresponders in vitro. No differences were instead observed between responders and nonresponders concerning platelet sensitivity to forskolin or dibutyryl cyclic AMP. The cyclic AMP rise obtained with exogenous prostacyclin was lower in platelets from nonresponders than in those from responders. PGE2 added in vitro to platelets from nonresponders exerted always a proaggregatory effect whereas this PG was antiaggregatory in most of the nonresponders. PGE2 blunted the antiaggregatory activity of PGD2 and limited the cyclic AMP increase induced by PGD2 in all the subjects tested. These data indicate that the unequal functional response of platelets from different subjects to thromboxane synthase inhibition depends essentially on adenylate cyclase function: a relative insensitivity of this enzyme to activating stimuli and the accumulation of substances (PGE2, PG endoperoxides, etc.) reducing the activity of adenylate cyclase may lead to continued platelet activation in some subjects despite the suppression of the synthesis of thromboxane A2.
ISSN: 0022-3565
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular and Vascular Biology
Laboratory for Clinical Infectious and Inflammatory Disorders
Chemistry, Campus Kulak Kortrijk
Interdisciplinary Research Facility Life Sciences, Campus Kulak Kortrijk
Faculty of Medicine - miscellaneous
× corresponding author
# (joint) last author

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