EFFECTS OF DOXEPIN ON ISOLATED BASILAR AND SAPHENOUS ARTERY RINGS OF RABBITS

AIM: To study the effects of doxepin (Dox) on cerebral artery. METHODS : The effects of Dox were observed using the isolated basilar and saph enous artery rings of rabbits. RESULTS: Dox inhibited the constriction of the basilar and saphenous artery rings evoked by KCl with IC50 5.7 5 mu mol . L-1 (95% confidence limits were 2.3 - 14 mu mol . L-1, n = 8) and 34.6 mu mol . L-1 (95% confidence limits were 3.8 - 316 mu mol L-1, n = 8), respectively. Dox also inhibited the constriction of the basilar and saphenous artery rings of the rabbits stimulated by 5-hydr oxytryptamine (5-HT), IC50 were 6.3 mu mol . L-1 (95% confidence limit s were 1.7 - 23.3 mu mol . L-1, n = 7) and 8.0 (mu mol . L-1(95% confi dence limits were 6.3 - 10.3 mu mol . L-1, n = 6), respectively. In bo th samples (basilar and saphenous artery rings) CaCl2 evoked, the pD(2 ) of Dox was 5.28 +/- 0.40 and 4.76 +/- 0.14, respectively (n = 6, P < 0.01). Dox 5.8 mu mol L-1 inhibited the constriction of the saphenous artery evoked by norepinephrine (NE) in Ca2+-free medium. Dox 30 mu m ol . L-1 inhibited the constriction of the saphenous artery evoked bot h by NE and by readmission of CaCl2 (1.25 mmol L-1). CONCLUSION: As co mpared with its effect on the saphenous artery, Dox selectively inhibi ted the basilar artery.