-transparent.png){kind=logo}
Amiloride inhibited the Na+Ca2+ exchange activity of cardiac sarcolemmal vesicles with similar affinities at the cis and trans sides of the membrane, estimated apparent Ki on both sides of the sarcolemma being similar. The extent of amiloride inhibition on Na+/Ca2+ exchange activity was decreased by alkaline pH only when the drug was acting from the external side of the vesicle sarcolemma, whereas when vesicles were preincubated with the drug at different pH values, amiloride appeared to act as a weak permeant base, being a more effective inhibitor at alkaline pH values. In fact, a rise in the pH of the preincubation medium may favour the entry and consequently the effect of the drug on the exchanger. The pH dependence of the inhibition of Na+/Ca2+ exchange activity by either extravesicular or intravesicular amiloride was consistent with the hypothesis that in both cases the protonated drug was the active form. Evidence is presented that the pattern of interaction of amiloride on the Na+/Ca2+ exchange system strictly depended on the sidedness of drug action. In fact, while Na+ protected against inhibition by amiloride when it was acting on the same side of the vesicle membrane as the drug, it synergically interacted with amiloride to inhibit exchange activity when it was acting on the opposite side of the sarcolemma as the drug. Furthermore, only extravesicular amiloride removed the stimulation of Na+/Ca2+ exchange activity in Ca2+-treated vesicles.
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
October 1984,
European journal of pharmacology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
March 1989,
The American journal of physiology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
September 1983,
Molecular pharmacology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
May 1985,
Molecular pharmacology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
September 1986,
Life sciences,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
March 1985,
Biochemistry,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
January 1997,
Molecular pharmacology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
August 1995,
Biochemistry,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
August 1991,
Naunyn-Schmiedeberg's archives of pharmacology,
P Debetto, and
S Luciani, and
M Tessari, and
M Floreani, and
F Carpenedo
October 1983,
FEBS letters,
