Abstract
1. The slow component of delayed rectification in the atrial muscle membrane of Rana ridibunda has been analysed quantitatively using a voltage-clamp technique.
2. It is shown that the current is proportional to a variable which obeys first-order kinetics. At negative potentials the time constant of this process is very long (τ = 3 sec at -55 mV) but it becomes faster at positive potentials (τ = 1·85 sec at +25 mV).
3. In the steady state the degree of activation is a sigmoid function of potential. The activation threshold varies substantially between preparations but is usually negative to -30 mV.
4. The instantaneous current—voltage relation is nearly linear and its reversal potential most frequently lies between zero and -30 mV.
5. The properties of this current system resemble those of the current system ix2 found in mammalian Purkinje fibres.
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Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Brown H. F., Noble S. J. Membrane currents underlying delayed rectification and pace-maker activity in frog atrial muscle. J Physiol. 1969 Oct;204(3):717–736. doi: 10.1113/jphysiol.1969.sp008940. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Noble D., Tsien R. W. Outward membrane currents activated in the plateau range of potentials in cardiac Purkinje fibres. J Physiol. 1969 Jan;200(1):205–231. doi: 10.1113/jphysiol.1969.sp008689. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Noble D., Tsien R. W. The kinetics and rectifier properties of the slow potassium current in cardiac Purkinje fibres. J Physiol. 1968 Mar;195(1):185–214. doi: 10.1113/jphysiol.1968.sp008454. [DOI] [PMC free article] [PubMed] [Google Scholar]