[Effects of 7-methoxy-4'-hydroxyl-3'-diethylaminomethylisoflavone (MHDF) on hemodynamics and aorta in rats].

MHDF is a synthetic isoflavone derivative with anti-ischemic effect. In this paper, the effects of MHDF on in vivo hemodynamics and in vitro contraction of rat aorta were reported. MHDF (3-12.8 mg/kg) was found to decrease +/- dP/dtmax, Vmax, Vpm and LVSP, prolong T-dP/dtmax of left ventricle and slow the HR in rats. It was also shown to inhibit the changes of heart performance induced by CaCl2 in rats. In isolated rat aorta, MHDF caused a noncompetitive antagonism of noradrenaline-and CaCl2-induced contraction with the pD2' of 3.11 +/- 0.21 and 3.73 +/- 0.07. The high K(+)-evoked contraction with IC50 of 17.6 mu mol/L was also found to be inhibited. The results suggest that the effect of MHDF on vascular muscle is different from that of an alpha-blocker and may be attributable to inhibition of extracellular calcium influx or intracellular calcium release.