ON the serotonin liberation from rat platelets due to betaadrenoceptor blocking drugs

The liberation of 14C-5HT and adenine nucleotides from rat platelets due to 10 betaadrenoceptor blocking drugs was studied. The most effective in liberating of 14C-5HT was pricoron, the less effective was atenolol. Except for pricoron all BAB drugs did not liberate adenine nucleotides from platelets. The depletion of adenine nucleotides due to pricoron was dose-dependent. Cold significantly decreased the effect of all betaadrenoceptor blocking drugs on serotonin liberation. The inhibitory effect of tetrodotoxin was evident on the effect of all drugs except of pricoron. Pretreatment of platelets with IAA,KCN, suramin, 5-HT or ASA was without effect. It is evident that most of the betaadrenoceptor blocking drugs liberate 5-HT from rat platelets by mechanism other than release reaction. The liberation induced with pricoron was result of cell lysis.