digoxin and bunazosin

The vascular effects of endogenous digitalis-like factors (EDLFs) extracted from the urine of hypertensive patients were investigated in isolated and perfused intermediate auricular and mesenteric arterial preparations of dogs. EDLFs produced a transient vasoconstriction in a dose-related manner in intermediate auricular arteries but only a slight constriction in mesenteric arteries. Ouabain induced a long-lasting vasoconstriction with tachyphylaxis in intermediate auricular arteries, but it did not constrict mesenteric arteries. EDLF-induced vasoconstrictions were reproducible and were not modified by alpha-adrenoceptor blockade. They were slightly suppressed by a potent calcium entry blocker, verapamil, in doses which markedly suppressed KCl-induced vasoconstrictions. Noradrenaline- and KCl-induced vasoconstrictions were not significantly modified by either EDLF or ouabain. From these results, it is concluded that EDLF has clear vasoconstrictor properties which are not due to adrenergic or calcium entry mechanisms and that there are differences in the vasoconstrictor effects of EDLFs with respect to different vascular beds. This is similar to what was found with ouabain.

Topics: Animals; Arteries; Blood Proteins; Cardenolides; Digoxin; Dogs; Ear, External; Epinephrine; Humans; Hypertension; In Vitro Techniques; Mesenteric Arteries; Ouabain; Phentolamine; Potassium Chloride; Quinazolines; Saponins; Vasoconstrictor Agents; Verapamil