Hyperpolarization-activated inward current in histaminergic tuberomammillary neurons of the rat hypothalamus

作者：Anita Kamondi, Peter B. Reiner · 发表于：Journal of Neurophysiology · 年份：1991 · DOI：10.1152/jn.1991.66.6.1902 · 被引用次数：76 · 研究领域：Neuroendocrine regulation and behavior、Circadian rhythm and melatonin、Photoreceptor and optogenetics research

1. Intracellular recordings were obtained from histaminergic tuberomammillary (TM) neurons of rat hypothalamus in an in vitro slice preparation. The properties of a time- and voltage-dependent inward current activated on hyperpolarization, Ih, were studied by use of the single-electrode voltage-clamp technique. 2. The activation curve of Ih was well fit by a sigmoidal function, with half-maximal activation occurring at -98 +/- 6 mV. 3. The estimated reversal potential of Ih (Eh) in TM neurons was -35 +/- 9 (SD) mV. 4. The time constant of activation was well fit by a single exponential function and exhibited marked voltage dependence: at -90 mV, Ih activated with a time constant of 823 +/- 35 ms, whereas at -130 mV, Ih activated with a time constant of 280 +/- 65 ms. The time constant of deactivation of Ih at -60 mV was 302 +/- 35 ms. 5. Raising the extracellular potassium concentration ([K+]o) to 10 mM shifted Eh to a more depolarized value, while lowering the extracellular sodium concentration [( Na+]o) shifted Eh in the negative direction. Altering the extracellular chloride concentration ([Cl-]o) had little effect on Eh. 6. Increasing [K+]o to 10 mM increased the amplitude of both Ih and its underlying conductance gh, while reducing [Na+]o caused a small reduction in the amplitude of Ih with no measurable effect on gh. 7. The time constant of activation of Ih became shorter in raised [K+]o and longer in lowered [Na+]o. 8. Extracellularly applied cesium blocked Ih in a vol...