Properties of the current if in the sino‐atrial node of the rabbit compared with those of the current iK, in Purkinje fibres.

作者：Dario DiFrancesco, C. Bosch Ojeda · 发表于：The Journal of Physiology · 年份：1980 · DOI：10.1113/jphysiol.1980.sp013475 · 被引用次数：193 · 研究领域：Neuroscience and Neural Engineering、Cardiac electrophysiology and arrhythmias、Electrochemical Analysis and Applications

1. Properties of the 'pace-maker' current if in rabbit sino-atrial node have been investigated by voltage clamp of small preparations and compared with those of the iK2 current in the Purkinje fibre. Besides having a similar voltage range of activation and responding in a similar way to adrenaline, if resembles iK2 in other respects. 2. When external Na is reduced, if decreases proportionally. In 25% Na the time-dependent current change due to if disappears. 3. 20 mM-Cs completely abolishes it. 4. The time constant of if during a hyperpolarizing voltage-clamp pulse displays a relatively high temperature dependence. 5. In spite of the similarities between the two current systems, experiments in high K solutions (48 mM) rule out the possibility that the current change seen on a hyperpolarization reflects the decay of a pure K current. 6. From conductance measurements during onset of if it is deduced that if behaves as an inward current activated by hyperpolarizations.