Human blood platelet alpha adrenoceptor in view of the effects of various imidazol(in)e drugs on aggregation.
1. Sixteen imidazol(in)e derivative drugs were tested with regards to their aggregatory and antiaggregatory effects on human blood platelets. 2. Platelet aggregation in response to fixed concentrations of the agents was quantified by the turbidimetric method of Born. 3. Inhibitory effects of the imidazol(in)es against the epinephrine (10(-5) M) induced aggregation was related to concentration of the agents. Of the compounds studied, UK 14,304 elicited an aggregatory effect of a magnitude similar to epinephrine. 4. A strong aggregatory agent appeared also moxonidine. 5. Small aggregation was observed in response to clonidine, antazoline and tetryzoline. 6. For all the group of imidazol(in)e drugs, excepting UK 14,304 and moxonidine, a significant inhibition of the epinephrine induced aggregation was noted. 7. Analysing inhibitory activity of imidazol(in)es one notes the drugs commonly assumed to interact with alpha 2 adrenoceptor among the most potent inhibitors, and those classified as alpha 1 adrenoceptor agonists among the less active agents. 8. The results here obtained suggest some similarity between the platelet adrenoceptor and the alpha 2 subtype of adrenoceptor identified in human circulatory system. 9. Differences appear between the two types of receptors and the existence of a separate alpha 3 class of adrenoceptors in human blood platelets should be considered.
Petrusewicz
J
J
Department of Biopharmaceutics and Pharmacodynamics, Medical Academy of Gdansk, Poland.
Kaliszan
R
R
D001792:Blood Platelets / Q000378:metabolism*; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*
D007093:Imidazoles; D010975:Platelet Aggregation Inhibitors; D011942:Receptors, Adrenergic, alpha; D004837:Epinephrine