Calcium-dependent action potentials and associated inward currents in guinea-pig neocortical neurons in vitro.
Calcium-dependent potential changes and inward currents were studied in guinea-pig neocortical neurons maintained in vitro. Under conditions of reduced outward potassium current, induced by external application of tetraethylammonium ions or internal application of caesium ions, regenerative Ca2+-dependent action potentials could be elicited. Strontium and barium ions could substitute for calcium as the charge carrier but not magnesium; cadmium blocked the calcium spikes. In caesium-loaded neurons, in the presence of tetrodotoxin and tetraethylammonium, inward currents were recorded when the membrane potential was step-depolarized to potentials more positive than -50 mV. These currents were blocked by cadmium. It is concluded that guinea-pig neocortical neurons are capable of generating a calcium action potential via the activation of a slow inward current.
Franz
P
P
Galvan
M
M
Constanti
A
A
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology*; D006168:Guinea Pigs; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials
D007473:Ion Channels; D002118:Calcium