Characterization of rebound depolarization in hippocampal neurons.
Rebound depolarization (RD) following hyperpolarizing pulses is found in several neuronal cell types where it takes part in the regulation of neuronal firing behavior. During whole-cell current and voltage clamp recordings in slice preparations, we investigated the modulation of RD by different stimulation patterns and its underlying ionic currents in rat CA1 pyramidal cells. RD was mainly carried by the hyperpolarization-activated cation current I(h) (about two-third) and T-type calcium currents (about one-third), respectively. RD increased with increasing hyperpolarizing amplitude and stimulation frequency, whereas RD substantially decreased with longer pulse duration and, less pronounced, with increasing pulse number. The pulse duration-related decrease of RD was due to a decrease of the driving force of I(h). In conclusion, we showed that RD is differentially modulated by precedent hyperpolarization. Since RD amplitude was high enough to generate action potentials, RD may serve, even under physiologic conditions, as an inhibition-excitation converter.
Surges
Rainer
R
Department of Neurology and Clinical Neurophysiology, University Clinics of Freiburg, Germany. rainer.surges@uniklinik-freiburg.de
Sarvari
Monika
M
Steffens
Marc
M
Els
Thomas
T
D000200:Action Potentials; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D004553:Electric Conductivity; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D007700:Kinetics; D008297:Male; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D020746:Calcium Channels, L-Type