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. 1980;308:353–367. doi: 10.1113/jphysiol.1980.sp013475

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

D DiFrancesco, C Ojeda
PMCID: PMC1274552  PMID: 6262501

Abstract

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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