Suchergebnisse

The hypothalamic paraventricular nucleus (PVN) is composed of functionally heterogeneous cell groups, possessing distinct electrophysiological properties depending on their functional roles. Previously, T-type Ca2+ dependent low-threshold spikes (LTS) have been demonstrated in various PVN neuronal types, including preautonomic cells. However, the molecular composition and functional properties of the underlying T-type Ca2+ channels have not been characterized. In the present study, we combined single cell reverse transcription–polymerase chain reaction (RT-PCR), immunohistochemistry and patch-clamp recordings to identify subtypes of T-type Ca2+ channels expressed in PVN cells displaying LTS (PVN-LTS), including identified preautonomic neurons. LTS appeared at the end of hyperpolarizing pulses either as long-lasting plateaus or as short-lasting depolarizing humps. LTS were mediated by rapidly activating and inactivating T-type Ca2+ currents and were blocked by Ni2+. Single cell RT-PCR and immunohistochemical studies revealed Cav3.1 (voltage-gated Ca2+ channel) as the main channel subunit detected in PVN-LTS neurons. In conclusion, these data indicate that Cav3.1 is the major subtype of T-type Ca2+ channel subunit that mediates T-type Ca2+ dependent LTS in PVN neurons. ; This work was supported by a Korea Research Foundation Grant funded by the Korean government (MOEHRD, Basic Research Promotion Fund) (KRF-2006-331-E00349) to S.Y.L. and by NIH RO1 HL 68725 to J.E.S.