Intracellular Free Ca²⁺ and Membrane Properties of Motoneurones

Abstract

IN some recent experiments on cats^1,2, it was found that 2,4-dinitrophenol strongly depresses the excitability of cortical neurones, probably by causing an increase in membrane conductance to K⁺ (g_K). It was suggested that the immediate cause of this effect may be an increased amount of free Ca²⁺ inside the neurone, resulting from slowing down of Ca²⁺ uptake by mitochondria (compare ref. 3). Although this idea is supported by the finding⁴ that injections of Ca²⁺ into neurones in Aplysia greatly increase membrane g_K, no comparable experiments have been performed in a more closely related species. The present communication describes some effects produced by injections of Ca²⁺ into mammalian neurones.