Influence of dimethyl sulfoxide (Me2SO) on vascular smooth muscle.

The present investigation was undertaken to determine the action of dimethyl sulfoxide (Me2SO) on vascular smooth muscle. The rabbit isolated aortic strip preparation was used. In the present study, Me2SO-induced relaxation of isolated rabbit aorta was demonstrated. The degree of relaxation induced by Me2SO was concentration dependent. In the presence of Me2SO the action of norepinephrine, histamine, carbachol and potassium was significantly (P less than .05) antagonized. The control ED50 values were 5.36 + 0.50 + 10(-8) M, 3.38 +/- 0.74 X 10(-6) M, 1.40 +/- 0.82 X 10(-6) M and 2.43 +/- 0.19 x 10(-2) M, respectively. In the presence of Me2SO the ED50 values were 2.23 +/- 0.23 x 10(-6) M, 1.80 +/- 0.40 X 10(-5) M, 1.00 +/- 0.38 X 10(-4) and 4.21 +/- 0.07 x 10(-2) M, respectively. The maximum response of the tissue to the various vasoactive agents was significantly depressed in the presence of Me2SO. When Me2SO was present in the efflux medium, the amount of 45Ca2+ washed out of aortic strips was significantly (P less than .05) reduced when compared to control. The 45Ca2+ efflux studies supported the hypothesis that Me2SO-induced relaxation could possibly result from enhanced binding of activator Ca2+ to high affinity Ca2+ sites.