Intracellular recordings from phycomyces.

Intracellular recordings from the giant sporangiophore of Phycomyces stage II were obtained. The mean transmembrane potential for 30 observations was -119.9 millivolts (negative inside), and it did not change either as a result of a light stimulus or during dark adaptation. Injected depolarizing and hyperpolarizing step currents and steady currents did not produce any avidence of spike activity. We conclude that light transduction and dark adaptation in Phycomyces are not based on alterations of the transmembrane potential.