A persistent sodium current in acutely isolated histaminergic neurons from rat hypothalamus.
Histamine neurons acutely dissociated from the tuberomammillary nucleus of the rat hypothalamus were studied in whole-cell and cell-attached patch-clamp experiments. Electrophysiological properties of dissociated cells were found to be similar to those recorded in slice experiments using microelectrodes. Tuberomammillary neurons fired spontaneously and this activity persisted when Cs+ (1.5 mM) was added to, or when K+ was removed from the extracellular solution. In whole-cell experiments a persistent tetrodotoxin-sensitive inward current was recorded. In cell attached recordings voltage-gated sodium channels displayed either normal or non-inactivating behavior. These results provide a further analysis of the properties of histaminergic neurons and indicate that spontaneous activity is intrinsic to individual neurons. Evidence for a non-inactivating tetrodotoxin-sensitive sodium current is presented. Single channel recordings indicate that this current is the result of non-inactivating behavior of sodium channels. Such a current is well suited for biasing tuberomammillary neurons toward spontaneous activity.
Uteshev
V
V
Department of Physiology, Heinrich-Heine Universität, Düsseldorf, Germany.
Stevens
D R
DR
Haas
H L
HL
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D006632:Histamine / Q000502:physiology*; D007031:Hypothalamus / Q000166:cytology* / Q000378:metabolism*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D008326:Mammillary Bodies / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D015222:Sodium Channels; D013779:Tetrodotoxin; D006632:Histamine