THE CARDIOVASCULAR EFFECTS OF TRIMAZOSIN AND PRAZOSIN IN THE RABBIT

摘要: SUMMARY 1. The cardiovascular effects of trimazosin, a quinazoline derivative similar in structure to prazosin, were investigated and compared with prazosin the rabbit. 2. Radioligand binding cerebral membranes showed that trimazosin has roughly 100-fold less affinity for α1-adrenoceptor. This was further supported by its lower pA2 derived from phenylephrine contractile responses isolated thoracic aorta preparations. 3. Trimazosin is extensively distributed clearance whole blood than although their elimination half-lives are comparable. In addition, it potent α1-adrenoceptor antagonist vivo, peripheral vascular depressor effect tends be greater prazosin. 4. at dose used under conditions study did not reverse pressor angiotensin II or B-HT920 but higher concentrations, unlike relaxed K+ contracted aorta. following pharmacological autonomie blockade treatment caused response. A though shorter lasting non-α1-receptor mediated action also observed prazosin. 5. 1-Hydroxytrimazosin (CP23445), major metabolite man, little either α1- α2-adrenoceptor radioligand studies. 6. addition antagonism, may exert an additional direct vasodilator rabbits.