Abstract
The activity of a calcium-activated nonselective (Ca-NS+) channel in a rat insulinoma cell line (CRI-G1) is inhibited by pyridine nucleotides in excised patches. The effects of all four pyridine nucleotides tested, β-NAD+, β-NADH, β-NADP+ and β-NADPH were very similar when tested at 0.1 mm, and at 1 mm the phosphorylated forms, β-NADP+ and β-NADPH, appeared to be slightly more potent than β-NAD+ and β-NADH. All the pyridine nucleotides tested reduced both the open state probability of the channel and the number of functional channels observed in a single patch.
The application of β-NAD+, but not of the other nucleotides tested, to the cytoplasmic surface of isolated inside-out patches from CRI-G1 cells opened a novel nonselective cation channel (the β-NAD+-NS+ channel). The activity of this new channel is calcium sensitive and may also be inhibited by AMP.
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We wish to thank Dr. P.D. Evans for his comments on the manuscript. V.R. was supported by a Research Assistantship funded by Serono Diagnostics U.K. Ltd. during the course of this work.
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Reale, V., Hales, C.N. & Ashford, M.L.J. The effects of pyridine nucleotides on the activity of a calcium-activated nonselective cation channel in the rat insulinoma cell line, CRI-G1. J. Membarin Biol. 142, 299–307 (1994). https://doi.org/10.1007/BF00233437
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DOI: https://doi.org/10.1007/BF00233437