Effects of ethacrynic acid and cardiac glycosides upon a membrane adenosinetriphosphatase of renal cortex

Implication of SH‐groups in the mitochondrial energy‐coupling system revealed by measurements of 14C‐ethacrynate incorporation into rat liver mitochondria

“…In previous work [ 1,2 ] it was shown that the thiol reagent [3,4], ethacrynate, inhibits or uncouples oxidative phosphorylation, depending on the substrate used and the experimental conditions. Among these previous findings, it was found that succinate oxidation is inhibited by ethacrynate but that inorganic phosphate (Pi) prevents this inhibition, ethacrynate and phosphate being competitive.…”

“…The present work was undertaken to study in different experimental conditions the incorporation of ethacrynate into mitochondria, and consequently, assuming that this incorporation is a measurement of the amount of free SH-groups [3,4], to follow the level of mitochondrial free SH-groups; it is shown that this level is increased by ADP but not by ATP, that the ADP-increase is oligomycin-sensitive and that antimycin and uncouplers decrease the thiol level and abolish the Pi sensitivity. We propose and discuss the existence of at least two different populations of thiol groups, one in close relation to the energy-coupling system, the other in connection with the phosphate-anion exchange system.…”

The effects of ethacrynic acid and other sulphydryl reagents on sodium fluxes in frog muscle

“…The inhibitory action of ethacrynic acid has been attributed to its ability to react with SH groups, due to the presence in the molecule of the drug of an olefinic bond conjugated to a benzoylcarbonyl ring (Duggan & Noll, 1965). To test whether its effects on efflux in frog muscle are related to this reactivity with SH groups we have compared in four experiments the effects of ethacrynic acid with those of a derivative in which the double bond has been saturated.…”

“…Since the action of ethacrynic acid may result from somewhat unselective binding to SH groups in the cell (Duggan & Noll, 1965) we have also performed experiments to elucidate whether its effects on sodium efflux can be attributed to a reaction with SH groups. 328 811 REAGENTS ON SODIUM FLUXES METHODS Paired sartorii dissected from the same frog (Rana pipiens or R. palmipes) were used to provide control and test muscles.…”

Combined effects of noise and ototoxic drugs.

“…The normal extracellular-like composition of the perilymph (high Na, low K) remains unaffected. Clearly, ion transport and/or permeability of the cochlear membranes such as Reissner's membrane, stria vascularis or the cochlear partition (organ of Corti and the basilar membrane) are exquisitely sensitive to ethacrynic acid, which has been shown to inhibit Na-K activated ATPase (47). Less sensitive to ethacrynic acid are the cochlear microphonic and auditory nerve action potential which undergo a reduction in amplitude with doses of 10 mg/kg.…”