Antifibrillatory effects of electrolyte-regulating steroids on isolated rabbit atria

Abstract

The effects of desoxycorticosterone (DOC) and a new synthetic steroid-17-spirolactone (SC 8109) were determined on the functional refractory periods (F. R. P.) and transmembrane fluxes of K in isolated rabbit atria and compared with the effects of quinidine. All three agents lengthened the F. R. P., inhibited the effects of acetylcholine (ACh), terminated or prevented ACh-induced fibrillation and depressed the transmembrane efflux of K. K influx was also decreased with higher concentrations of the steroids or after a delay in time. Aldosterone and delta-1–9 alpha-flurohydrocortisone had no effect on the F. R. P. or K fluxes. It was concluded that DOC, spirolactone and quinidine act similarly as antiarrhythmic compounds by depressing Na entry.