Summary
ATP-inhibited potassium channels (K(ATP)) were studied in excised, inside-out patches from cultured adult mouse pancreatic β-cells and HIT cells. In the absence of ATP, ADP opened K(ATP) channels at concentrations as low as 10 μ m and as high as 500 μ m, with maximal activation between 10 and 100 μ m ADP in mouse β-cell membrane patches. At concentrations greater than 500 μ m, ADP inhibited K(ATP) channels while 10 mm virtually abolished channel activity. HIT cell channels had a similar biphasic response to ADP except that more than 1 mm ADP was required for inhibition. The channel opening effect of ADP required magnesium while channel inhibition did not. Using creatine/creatine phosphate solutions with creatine phosphokinase to fix ATP and ADP concentrations, we found substantially different K(ATP)-channel activity with solutions having the same ATP/ADP ratio but different absolute total nucleotide levels. To account for ATP-ADP competition, we propose a new model of channel-nucleotide interactions with two kinds of ADP binding sites regulating the channel. One site specifically binds MgADP and increases channel opening. The other, the previously described ATP site, binds either ATP or ADP and decreases channel opening. This model very closely fits the ADP concentration-response curve and, when incorporated into a model of β-cell membrane potential, increasing ADP in the 10 and 100 μ m range is predicted to compete very effectively with millimolar levels of ATP to hyperpolarize β-cells.
The results suggest that (i) K(ATP)-channel activity is not well predicted by the “ATP/ADP ratio,” and (ii) ADP is a plausible regulator of K(ATP) channels even if its free cytoplasmic concentration is in the 10–100 μ m range as suggested by biochemical studies.
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Akerboom, T.P.M., Bookelman, H., Zuurendonk, P.F., Van der Meer, R., Tager, J.M. 1978. Intramitochondrial and extramitochondrial concentrations of adenine nucleotides and inorganic phosphate in isolated hepatocytes from fasted rats. Eur. J. Biochem. 84:413–420
Albitz, R., Kammermeier, H., Nilius, B. 1990. Free energy of ATP-hydrolysis fails to affect ATP-dependent potassium channels in isolated mouse ventricular cells. J. Mol. Cell. Cardiol. 22:183–190
Ashcroft, F.M., Harrison, D.E., Ashcroft, S.J.H. 1984. Glucose induces closure of single potassium channels in isolated rat pancreatic β-cells. Nature 312:446–448
Ashcroft, F.M., Kakei, M. 1989. ATP-sensitive K+ channels in rat pancreatic β-cells: Modulation by ATP and Mg2+ ions. J. Physiol. 414:349–367
Ashcroft, F.M., Rorsman, P. 1990. ATP-sensitive K+ channels: A link between B-cell metabolism and insulin secretion. Biochem. Soc. Trans. 18:109–111
Ashcroft, S.J.H., Weerasinghe, L.C.C., Randle, P.J. 1973. Interrelationship of islet metabolism, adenosine triphosphate content, and insulin release. Biochem. J. 132:223–231
Bokvist, K., Ämmälä, C., Ashcroft, F.M., Berggren, P.-O., Larsson, O., Rorsman, P. 1991. Separate process mediate nucleotide-induced inhibition and stimulation of the ATP-regulated K+-channels in mouse pancreatic B-cells. Proc. R. Soc. London B. 243:139–144
Cook, D. L., Hales, C. N. 1984. Intracellular ATP directly blocks K+ channels in pancreatic islet cells. Nature 311:271–273
Cook, D.L., Satin, L.S., Ashford, M.L.J., Hales, C.N. 1988. ATP-sensitive K+ channels in pancreatic B-cells: Spare channel hypothesis. Diabetes 37:495–498
Cook, D.L., Satin, L.S., Hopkins, W.F. 1991. Pancreatic B-cells are bursting, but how? Trends Neurosci. 14:411–414
Corkey, B.E., Deeney, J.T., Glennon, M.C., Matschinsky, F.M., Prentki, M. 1988. Regulation of steady-state free Ca2+ levels by the ATP/ADP ratio and orthophosphate in permeabilized RINm5F insulinoma cells. J. Biol. Chem. 263:4247–4253
Dean, P.M. Matthews, E.K. 1970. Glucose-induced electrical activity in pancreatic islet cells. J. Physiol. 210:255–264
Dunne, M.J., Petersen, O.H. 1986. Intracellular ADP activities K+ channels that are inhibited by ATP in an insulin-secreting cell line. FEBS Lett. 208:59–62
Dunne, M.J., West, J.J., Abraham, R.J., Edwards, R.H., Petersen, O.H. 1988. The gating of nucleotide-sensitive K+ channels in insulin-secreting cells can be modulated by changes in the ratio ATP4−/ADP3− and by nonhydrolyzable derivatives of both ATP and ADP. J. Membrane Biol. 104:165–177
Fabiato, A. 1988. Computer programs for calculating total from specified or free from specified total ionic concentrations in aqueous solutions containing multiple metals and ligands. In: Methods in Enzymology. S. Fleischer and B. Fleischer, editors. Vol. 157, pp. 378–417. Academic, San Diego
Findlay, I. 1987. The effects of magnesium upon adenosine triphosphate-sensitive potassium channels in a rat insulin-secreting cell line. J. Physiol. 391:611–629
Findlay, I., Dunne, M.J. 1986. ATP maintains ATP-inhibited K+ channels in an operational state. Pfluegers Arch. 407:238–240
Ghosh, A., Ronner, P., Cheong, E., Khalid, P., Matschinsky, F.M. 1991. The role of ATP and free ADP in metabolic coupling during fuel-stimulated insulin release from islet β-cells in the isolated perfused rat pancreas. J. Biol. Chem. 266:22887–22892
Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F.J. 1981. Improved patch clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pfluegers Arch. 391:85–100
Hopkins, W.F., Cook, D.L. 1991. Stimulation of ATP-sensitive K+ channel activity by ADP in excised patches from cultured mouse pancreatic B-cells. Soc. Neurosci. 17:1474 (Abstr.)
Jacobus, W.E., Moreadith, R.W., Vandegaer, K.M. 1982. Mitochondrial respiratory control: Evidence against the regulation of respiration by extramitochondrial phosphorylation potential or by [ATP]/[ADP] ratios. J. Biol. Chem. 257:2397–2402
Kakei, M., Kelly, R.P., Ashcroft, S.J., Ashcroft, F.M. 1986. The ATP-sensitivity of K+ channels in rat pancreatic B-cells is modulated by ADP. FEBS Lett. 208:63–66
Koretsky, A.P., Brosnan, M.J., Chen, L., Chen, J., Van Dyke, T. 1990. NMR detection of creatine kinase expressed in liver of transgenic mice: Determination of free ADP levels. Proc. Natl. Acad. Sci. USA 87:3112–3116
Lederer, W.J., Nichols, C.G. 1989. Nucleotide modulation of the activity of rat heart ATP-sensitive K+ channels in isolated membrane patches. J. Physiol. 419:193–211
Malaisse, W.J., Hutton, J.C., Kawazu, S., Herchuelz, A., Valverde, I., Sener, A. 1979. The stimulus secretion coupling of glucose induced insulin release. XXXV. The links between metabolic and cationic events. Diabetologia 16:331–341
Meissner, H.P., Schmelz, H. 1974. Membrane potential of betacells in pancreatic islets. Pfluegers Arch. 351:195–206
Misler, S., Falke, L.C., Gillis, K., McDaniel, M.L. 1986. A metabolite-regulated potassium channel in rat pancreatic B-cells. Proc. Natl. Acad. Sci. USA 83:7119–7123
Nichols, C.G., Lederer, W.J. 1990. The regulation of ATP-sensitive K+ channel activity in intact and permeabilized rat ventricular myocytes. J. Physiol. 423:91–110
Ohno-Shosaku, T., Zünkler, B.J., Trube, G. 1987. Dual effects of ATP on K+ currents of mouse pancreatic B-cells. Pfluegers Arch. 408:133–138
Ohta, M., Nelson, D., Nelson, J., Meglasson, M.D., Erecinska, M. 1991. Relationship between energy level and insulin secretion in isolated rat islets of Langerhans. Biochem. Pharmacol. 42:593–598
Ribalet, B., Beigelman, P.M. 1980. Calcium action potentials and potassium permeability activation in pancreatic B-cells. Am. J. Physiol. 239:C124-C133
Rorsman, P., Trube, G. 1985. Glucose dependent K-channels in pancreatic B-cells are regulated by intracellular ATP. Pfluegers Arch. 405:305–309
Santerre, R.F., Cook, R.A., Crisel, R.M.S.D., Sharp, J.D., Schmidt, R.J., Williams, D.C., Wilson, C.P. 1981. Insulin synthesis in a clonal cell line of simian virus 40-transformed hamster pancreatic beta cells. Proc. Natl. Acad. Sci. USA 78:4339–4343
Tung, R.T., Kurachi, Y. 1991. On the mechanism of nucleotide diphosphate activation of the ATP-sensitive K+ channel in ventricular cell of guinea-pig. J. Physiol. 437:239–256
Veech, R.L., Lawson, J.W.R., Cornell, N.W., Krebs, H.A. 1979. Cytosolic phosphorylation potential. J. Biol. Chem. 254:6538–6547
Wollheim, C.B., Pozzan, T. 1984. Correlation between cytosolic free Ca2+ and insulin release in an insulin-secreting cell line. J. Biol.Chem. 259:2262–2267
Wollheim, C.B., Sharp, W.G. 1981. Regulation of insulin release by calcium. Physiol. Rev. 61:914–973
Yellen, G. 1982. Single Ca2+-activated nonselective cation channels in neuroblastoma. Nature 296:357–359
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We would like to thank Mr. Louis Stamps for expert technical assistance and Dr. Wil Fujimoto and Ms. Jeanette Teague for generously providing HIT cells obtained from Dr. Robert Santerre at Eli Lilly. We would also like to thank Dr. Michel Vivaudou for providing the program ALEX. Support was provided by the NIH and the Department of Veterans Affairs.
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Hopkins, W.F., Fatherazi, S., Peter-Riesch, B. et al. Two sites for adenine-nucleotide regulation of ATP-sensitive potassium channels in mouse pancreatic β-cells and HIT cells. J. Membarin Biol. 129, 287–295 (1992). https://doi.org/10.1007/BF00232910
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DOI: https://doi.org/10.1007/BF00232910