Effect of Na+,K+,2Cl- cotransport inhibitor bumetanide on electrical and contractile activity of smooth muscle cells in guinea pig ureter

The effect of Na+,K+,2Cl(-) cotransport inhibitor bumetanide on action potentials and contractions of smooth muscle cells in the ureter of guinea pigs evoked by electrical stimulation was studied by the method of double sucrose bridge. Bumetanide (10-100 muM) dose-dependently suppressed action potential and contractions of smooth muscle cells induced by 1-10 muM histamine, 10 muM mesatone, 5 mM tetraethylammonium, and 100 muM sodium nitroprusside. Our findings suggest that test substances modulate Na+,K+,2Cl(-) cotransport in smooth muscle cells.