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Effects of Imidazoline and Non-Imidazoline α-Adrenergic Agents on Canine Platelet Aggregation

1999; Karger Publishers; Volume: 58; Issue: 4 Linguagem: Inglês

10.1159/000028279

1423-0313

Yoshiaki Hikasa, Mizue Abe, Takahiro Satoh, Yoko Hisashi, Shigeo OGASAWARA, Hiroshi Matsuda,

Hormonal and reproductive studies

Aggregatory and antiaggregatory effects of imidazol(in)e and non-imidazol(in)e α-adrenergic agents on canine platelets were examined turbidimetrically in citrated platelet-rich plasma or washed platelet solution. Each α-adrenoceptor agonist alone did not induce aggregation, but adrenaline and noradrenaline potentiated dose-dependently aggregation stimulated by ADP, collagen or thrombin. Small potentiation of ADP- or collagen-stimulated aggregation was also observed in response to oxymetazoline. The α₂-adrenoceptor antagonists and/or imidazol(in)e α-adrenergic agents inhibit dose-dependently adrenaline-potentiated aggregation, whereas α₁-adrenoceptor antagonists, a β-adrenoceptor antagonist and non-imidazol(in)e α-adrenergic agents were no or less effective in inhibiting adrenaline-potentiated aggregation. The α₂-adrenoceptor agonists did not reduce inhibitory effect of α₂-adrenoceptor antagonists for adrenaline-potentiated aggregation. The α₂-adrenoceptor antagonists and/or imidazol(in)es were no or less effective in inhibiting aggregation induced by ADP or thrombin alone. These results demonstrated that α₂-adrenoceptor-blocking agents and/or imidazol(in)e α-adrenergic agents inhibit effectively the adrenaline-potentiated platelet aggregation.