Properties of a hyperpolarization‐activated cation current and its role in rhythmic oscillation in thalamic relay neurones.

作者：David A. McCormick, Hans‐Christian Pape · 发表于：The Journal of Physiology · 年份：1990 · DOI：10.1113/jphysiol.1990.sp018331 · 被引用次数：1155 · 研究领域：Neuroscience and Neuropharmacology Research、Neural dynamics and brain function、Photoreceptor and optogenetics research

1. The physiological and functional features of time-dependent anomalous rectification activated by hyperpolarization and the current which underlies it, Ih, were examined in guinea-pig and cat thalamocortical relay neurones using in vitro intracellular recording techniques in thalamic slices. 2. Hyperpolarization of the membrane from rest with a constant-current pulse resulted in time-dependent rectification, expressed as a depolarizing sag of the membrane potential back towards rest. Under voltage clamp conditions, hyperpolarizing steps to membrane potentials negative to approximately -60 mV were associated with the activation of a slow inward current, Ih, which showed no inactivation with time. 3. The activation curve of the conductance underlying Ih was obtained through analysis of tail currents and ranged from -60 to -90 mV, with half-activation occurring at -75 mV. The time course of activation of Ih was well fitted by a single-exponential function and was strongly voltage dependent, with time constants ranging from greater than 1-2 s at threshold to an average of 229 ms at -95 mV. The time course of de-activation was also described by a single-exponential function, was voltage dependent, and the time constant ranged from an average of 1000 ms at -80 mV to 347 ms at -55 mV. 4. Raising [K+]o from 2.5 to 7.5 mM enhanced, while decreasing [Na+]o from 153 to 26 mM reduced, the amplitude of Ih. In addition, reduction of [Na+]o slowed the rate of Ih activation. These results ...