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. 1973 Feb;229(1):99–113. doi: 10.1113/jphysiol.1973.sp010129

Effects of noradrenaline and isoprenaline, in combination with α- and β-receptor blocking substances, on the action potential of cardiac Purkinje fibres

A Giotti, F Ledda, P F Mannaioni
PMCID: PMC1350214  PMID: 4689996

Abstract

1. The effects of noradrenaline and isoprenaline on the repolarization phase of the action potential have been studied in the Purkinje fibres of sheep heart, electrically driven at constant rates.

2. Isoprenaline (2, 5 and 8 × 10-8 g/ml.) increases the slope of phase 2 of repolarization and decreases the plateau length; the resulting decrease in action potential duration is concentration dependent, but not rate dependent.

3. The effect of isoprenaline on the action potential duration is entirely blocked by propranolol (10-7 g/ml.) and unaffected by phentolamine (5 × 10-7 g/ml.).

4. In phentolamine (5 × 10-7 g/ml.) pretreated preparations the response induced by noradrenaline (5 × 10-8, 1 and 5 × 10-7 g/ml.) is very similar to that induced by isoprenaline.

5. In propranolol (2·5 × 10-7 g/ml.) pretreated preparations noradrenaline causes a lengthening of the plateau phase and an increase in action potential duration.

6. The relationship of these results to the presence of both α- and β-receptors in cardiac Purkinje fibres is discussed.

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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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