Effect of labetalol on human platelet function.
1. The effects of the alpha-beta-adrenergic antagonist labetalol on the activation of human platelets by adrenaline and other aggregating stimuli have been investigated. 2. Labetalol inhibited platelet aggregation and secretion induced by collagen and the second phase of aggregation caused by ADP, platelet activating factor, adrenaline and ionophore A23187. Adrenaline-induced platelet activation was inhibited by the lowest labetalol concentration. The response to Na arachidonate was minimally affected and the arachidonate-induced thromboxane B2 generation was only partially prevented. 3. The pre-incubation with low concentration of ionophore A23187 overcame labetalol's inhibition of collagen-induced platelet aggregation. 4. Labetalol did not influence intraplatelet cyclic AMP levels. 5. The present investigation provided evidences that the modulation of human platelet function by labetalol could be related also to a decreased Ca2+ availability.
Anfossi
G
G
Cattedra di Clinica Medica III, University of Turin, Italy.
Trovati
M
M
Lanzio
M
M
Mularoni
E
E
Massucco
P
P
Emanuelli
G
G
D000328:Adult; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002395:Catecholamines / Q000494:pharmacology; D000242:Cyclic AMP / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D007741:Labetalol / Q000494:pharmacology*; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors; D010978:Platelet Factor 4 / Q000378:metabolism; D010979:Platelet Function Tests; D013929:Thromboxane B2 / Q000097:blood; D001620:beta-Thromboglobulin / Q000378:metabolism
D002395:Catecholamines; D010975:Platelet Aggregation Inhibitors; D001620:beta-Thromboglobulin; D010978:Platelet Factor 4; D013929:Thromboxane B2; D000242:Cyclic AMP; D007741:Labetalol