title: An adenylate kinase is involved in KATP channel regulation of mouse pancreatic beta cells.
abstract: OBJECTIVE
  In a previous study, we demonstrated that a creatine kinase (CK) modulates K(ATP) channel activity in pancreatic beta cells. To explore phosphotransfer signalling pathways in more detail, we examined whether K(ATP) channel regulation in beta cells is determined by a metabolic interaction between adenylate kinase (AK) and CK.
  
  
  METHODS
  Single channel activity was measured with the patch-clamp technique in the inside-out (i/o) and open-cell attached (oca) configuration.
  
  
  RESULTS
  The ATP sensitivity of K(ATP) channels was higher in i/o patches than in permeabilised beta cells (oca). One reason for this observation could be that the local ATP:ADP ratio in the proximity of the channels is determined by factors not active in i/o patches. AMP (0.1 mmol/l) clearly increased open channel probability in the presence of ATP (0.125 mmol/l) in permeabilised cells but not in excised patches. This suggests that AK-catalysed ADP production in the vicinity of the channels is involved in K(ATP) channel regulation. The observation that the stimulatory effect of AMP on K(ATP) channels was prevented by the AK inhibitor P (1),P (5)-di(adenosine-5')pentaphosphate (Ap(5)A; 20 micromol/l) and abolished in the presence of the non-metabolisable ATP analogue adenosine 5'-(beta,gamma-imido)triphosphate tetralithium salt (AMP-PNP; 0.12 mmol/l) strengthens this idea. In beta cells from AK1 knockout mice, the effect of AMP was less pronounced, though not completely suppressed. The increase in K(ATP) channel activity induced by AMP in the presence of ATP was outweighed by phosphocreatine (1 mmol/l). We suggest that this is due to an elevation of the ATP concentration by CK.
  
  
  CONCLUSIONS
  We propose that phosphotransfer events mediated by AK and CK play an important role in determining the effective concentrations of ATP and ADP in the microenvironment of pancreatic beta cell K(ATP) channels. Thus, these enzymes determine the open probability of K(ATP) channels and eventually the actual rate of insulin secretion.
authors: Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
authors: D U
authors: DU
authors: Schulze
authors: M
authors: M
authors: Düfer
authors: B
authors: B
authors: Wieringa
authors: P
authors: P
authors: Krippeit-Drews
authors: G
authors: G
authors: Drews
mesh_terms: D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000502:physiology; D000263:Adenylate Kinase / Q000378:metabolism*; D000818:Animals; D004594:Electrophysiology / Q000379:methods; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000502:physiology*; D054086:KATP Channels / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D018408:Patch-Clamp Techniques
chemical_list: D054086:KATP Channels; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D000263:Adenylate Kinase
references: FEBS Lett. 1986 Nov 10;208(1):63-6
references: 2429869
references: Mol Cell Biochem. 2004 Jan-Feb;256-257(1-2):243-56
references: 14977185
references: Diabetologia. 1979 May;16(5):331-41
references: 37138
references: Proc Natl Acad Sci U S A. 1996 May 14;93(10):5161-5
references: 8643546
references: Biochem Pharmacol. 1997 Jul 15;54(2):219-25
references: 9271325
references: J Biol Chem. 1973 Feb 10;248(3):1121-3
references: 4734335
references: J Physiol. 2002 Dec 1;545(Pt 2):501-7
references: 12456829
references: Diabetes. 2004 Dec;53 Suppl 3:S63-6
references: 15561924
references: FASEB J. 2002 Jan;16(1):102-4
references: 11729098
references: Science. 1996 Jun 21;272(5269):1785-7
references: 8650576
references: Biochim Biophys Acta. 1987 Feb 18;927(2):190-5
references: 2434137
references: Mol Cell Endocrinol. 2005 Jan 31;230(1-2):51-8
references: 15664451
references: EMBO J. 2000 Dec 1;19(23 ):6371-81
references: 11101510
references: J Biol Chem. 1998 Nov 20;273(47):31395-400
references: 9813050
references: Diabetes. 1980 Jan;29(1):1-14
references: 6991311
references: J Biol Chem. 1991 Dec 5;266(34):22887-92
references: 1744082
references: Nature. 1984 Sep 20-26;311(5983):271-3
references: 6090930
references: J Biol Chem. 1996 Dec 13;271(50):31903-8
references: 8943234
references: FEBS Lett. 1989 Nov 6;257(2):361-4
references: 2555221
references: Biochem J. 2003 Oct 1;375(Pt 1):1-16
references: 12839490
references: J Physiol. 1990 Apr;423:91-110
references: 2388163
references: Diabetes. 2003 Oct;52(10):2630-5
references: 14514649
references: Diabetes. 2006 Oct;55(10):2826-34
references: 17003349
references: Diabetes. 1996 Oct;45(10):1431-4
references: 8826982
references: Proc Natl Acad Sci U S A. 2001 Jun 19;98(13):7623-8
references: 11390963
references: J Physiol. 1993 Apr;463:349-65
references: 8246187
references: J Biol Chem. 1996 Jul 12;271(28):16544-52
references: 8663240
references: Nucleic Acids Res. 2005 Jan 1;33(Database issue):D544-9
references: 15608258
references: J Biol Chem. 1998 Dec 18;273(51):33905-8
references: 9852040
references: Pflugers Arch. 2003 Feb;445(5):556-62
references: 12634926
references: Diabetes. 1972;21(2 Suppl):555-69
references: 4559920
references: J Membr Biol. 1988 Sep;104(2):165-77
references: 3057214
references: J Biol Chem. 1998 Oct 9;273(41):26383-7
references: 9756869
references: Science. 1998 Nov 6;282(5391):1141-4
references: 9804555
references: J Physiol. 1985 Jun;363:441-62
references: 2410608
references: J Biol Chem. 2006 Feb 3;281(5):3006-12
references: 16332676
references: Diabetes. 2006 Sep;55(9):2446-54
references: 16936192
references: Endocr Rev. 1999 Apr;20(2):101-35
references: 10204114
references: J Physiol. 1988 Oct;404:731-47
references: 2855352
references: Diabetes. 2005 Oct;54(10 ):2852-2858
references: 16186385
references: FASEB J. 1998 May;12(7):523-9
references: 9576479
references: Science. 1998 Nov 6;282(5391):1059-60
references: 9841452
references: J Endocrinol. 1986 May;109(2):201-7
references: 2423630
references: Science. 1998 Nov 6;282(5391):1138-41
references: 9804554
references: Diabetes. 2002 Feb;51(2):376-84
references: 11812744
references: Nature. 1997 May 8;387(6629):179-83
references: 9144288
references: J Exp Biol. 2003 Jun;206(Pt 12):2039-47
references: 12756286