Abstract: To investigate whether Diamox （Acetazolamide） or dipyridamole can dilate the abdominal aortic ring in rabbit directly and its mechanism also, six rabbits with the body weight of 2.33±0.18 kg were anaesthetized and the aortic rings about 5mm long were quickly excised and emerged in oxygen saturated Kreb’s solution. The aortic ring was connected to a force transducer by one thread and fixed by another. The tension signal was transmitted to and analyzed by a microcomputer. After 10 minutes of stabiliza-tion ,the preload was set at 1.96×10^-2 N and force signal was recoreded. Then the aor-tic ring was contracted with norepinephrine. Fifteen minutes later, 15 mg of Diamox or dipyridamole was given. If vasodilatation was observed, 0.045g of sodium iodide was given 15 minutes after norepinephrine. Besides this, N-omega-L-arginine-methyl-evSter, glibenclamide，clotrimazole or indomethacin was given before norepinephrine,and Diamox was given 15 minutes after norepinephrine. The results showed that norepinephrine induced rise in force did not change during the 30 minutes observation period. Diamox significantly dilated the aortic ring but sodium iodide did not. Dipyridamole did not influence the tension of aortic ring. Clotrimazole significantly abolished the vasodilating effect of Diamox. Nw-nitro-L-arginine-methy 1-ester, glibenclamide or indomethacin did not influence the vasodilating effect of Diamox. Conclusions：Diamox can directly dilate the rabbit’s aortic ring. Dipyridamole does not have any direct vasodilating effect on the rabbit’s abdominal aorta.

Key words: Acetazolamide, Dipyridamole, Rabbit, Vasodilatation