Abstract
THE action potential in many nerve cells is followed by an after-hyperpolarisation (AH). In several types of neurone, this AH consists of two components: a brief voltage-sensitive K+ conductance, and a longer Ca2+-sensitive K+ conductance (refs 1–5, see ref. 6 for review). In sympathetic neurones of the bullfrog, theophylline potentiates this Ca2+-sensitive K+ conductance4. As theophylline is a well known inhibitor of phosphodiesterase7, the enzyme which catabolises cyclic nucleotides, we examined the role of cyclic nucleotide metabolism in the regulation of the spike AH. We used both electrophysiological and biochemical methods to investigate whether potentiation of the spike AH by theophylline is correlated with cyclic nucleotide elevation in bullfrog sympathetic neurones. Our results indicate that the potentiation of this Ca2+-dependent K+ conductance is apparently independent of cyclic AMP and cyclic GMP levels, and suggest that this potentiation by theophylline is not due to inhibition of phosphodiesterase.
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SMITH, P., WEIGHT, F. & LEHNE, R. Potentiation of Ca2+-dependent K+ activation by theophylline is independent of cyclic nucleotide elevation. Nature 280, 400–402 (1979). https://doi.org/10.1038/280400a0
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DOI: https://doi.org/10.1038/280400a0
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