VASODILATORY EFFECT OF SULFUR DIOXIDE-DERIVATIVES ON ISOLATED AORTIC RINGS OF RAT

To investigate the direct effects and possible mechanisms of sulfur dioxide(SO 2 )-derivatives (the mixture of sodium bisulfite and sodium sulfite) on vascular tension, the effects of SO 2 -derivatives on isometric force of isolated rat aortic rings were examined, and the change in vascular tension of rat aortic rings pretreated with N-L-nitro-arginine, methylene blue, indomethacin and propranolol respectively was studied. It was found that the SO 2 derivatives could dose-dependently relax the isolated aorta precontracted with noradrenaline (NE) or potassium chloride (KCl); the vasodilatory effect on the aortic rings precontracted with NE was more potent than that precontracted with KCl; this effect was attenuated when the aortic rings were preincubated with indomethacin; and this effect was not affected by indomethacin, methylene blue and propranolol. It was primarily demonstrated that the SO 2 derivatives could dilate vas, which was related to prostacyclin (PGI 2), but had nothing to do with nitric oxide (NO). Fig 2, Tab 1, Ref 12