Intracellular recordings from pineal cells in tissue culture: membrane properties and response to norepinephrine

Membrane properties and responsiveness to norepinephrine were studied in pinealocytes in tissue culture using both conventional and whole-cell patch-clamp techniques. Action potentials could be recorded in normal and tetrodotoxin-containing saline. Both outward and inward rectification were prominent. Under voltage-clamp, depolarizing voltage steps evoked time-dependent outward currents showing no inactivation over time. Hyperpolarizing steps evoked slowly developing inward currents which did not inactivate. If the holding potential was sufficiently negative, depolarizing steps also elicited a transient outward current. Iontophoresis of norepinephrine produced a hyperpolarization in 30% of cells tested.