The 24Na-transport increasing effect of veratrine in frog sartorius muscle influenced by the tonicity, composition and temperature of the external environment

The uptake and efflux of 24Na were studied in frog sartorius muscle preparations. In isotonic Ringer solution veratrine increased 24Na-efflux and the uptake of 24Na and lithium. All these effects were absent in hypertonic medium. The dependence on external temperature and on veratrine concentration was also examined. It is concluded that measurements in hypertonic medium make possible to distinguish the effect of veratrine on muscular membranes from its effect on neural structures. (author)