The effects of sodium pump inhibitors on sensory ganglion neurite growth

The effects of sodium pump inhibitors of the cardiac glycoside family (strophanthin K and digoxin) on neurite growth in the sensory ganglia of chick embryos (10–12 days) were studied in organotypic tissue cultures. These experiments produced the first evidence that these medicinal agents have marked neurite-suppressing actions. Their effects on sensory ganglion neurite growth were dose-dependent. At 1·10 −6 M, strophanthin K and digoxin completely blocked sensory ganglion neurite growth. Addition of study compounds to the medium at a concentration of 1· 10 −7 M decreased the area index of the experimental explants to a level significantly below that of the controls, by a mean of 45%. These strophanthin K and digoxin concentrations were comparable with those at which endogenous digitalis-like factors are present in the systemic circulation. These results provide evidence that cardiac glycosides can produce the directed regulation of nervous tissue growth by affecting the signal transducer Na + , K + -ATPase.