Intracellular Ca2+ and Ca2+-permeable ion channels are important in regulating the firing activity and pattern of midbrain dopamine neurons, but the role of Ca2+-permeable nonselective cation channels (NSCCs) on spontaneous firing activity is unclear. Therefore, we investigated how Ca2+-permeable NSCCs modulate spontaneous firing activity and cytosolic Ca2+ concentration ([Ca2+]c) in acutely isolated midbrain dopamine neurons of the rat. Applications of voltage-dependent Ca2+ channels antagonists failed to abolish spontaneous firing activity completely, but they decreased firing rate and [Ca2+]c. However, a blockade of NSCCs by 2-APB or SKF96365 more potently suppressed spontaneous firings with a depolarization of membrane potential and strong decreases in basal [Ca2+]c levels. The depolarization of membrane potentials was attenuated by intracellular dialysis with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). NSCCs blockers inhibited oscillatory potentials and decreased basal [Ca2+]c in the presence of tetrodotoxin. Apamin, a small-conductance Ca2+-activated K+ channel inhibitor, depolarized membrane potentials and enhanced firing rates. From these data, we conclude that NSCCs not only make up the tonic Ca2+ entry pathways to uphold basal [Ca2+]c levels but also contribute to generation of spontaneous firings, thereby regulating spontaneous firing activities of the midbrain dopamine neurons.

The synthesis and nanoscale dispersion of a new one-dimensional (1D) material, V 2 Se 9 , in which chainshaped molecular units with strong covalent bonds are assembled in a crystal structure via weak van der Waals attraction between chains, were successfully carried out. V 2 Se 9 is synthesized by solid-state reaction and additional heat treatment. The synthesized V 2 Se 9 has excellent thermal stability up to 400 C and has been experimentally confirmed to be dispersed up to $20 nm or less through a specific solvent dispersion. The covalently bonded V 2 Se 9 chain, when isolated from its bulk material, is expected to exhibit unique quantum physical properties owing to the confinement of electrons in the 1D chain structure and the absence of inter-chain interactions, as demonstrated in the case of graphene and other 2D materials. Therefore, the novel 1D material of V 2 Se 9 , as an extension of the current 2D material, is expected to create a new class of materials that will be of significant interest to the materials science and nanotechnology communities for new device applications. † Electronic supplementary information (ESI) available: EDS mappings of samples in Fig. 2 synthesized at 380 C, 340 C and 330 C (Fig. S1), XRD patterns, SEM images and EDS analysis of as-synthesized samples with temperature ranging from 300 C to 400 C (Fig. S2). IR absorption spectrum of V 2 Se 9 (Fig. S3). See