| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Medical Physics, Gothenburg University, Sweden.
1. The mechanisms by which ADP and the hyperglycaemic compound diazoxide stimulate the activity of the ATP-regulated K+ channel (KATP channel) were studied using inside-out patches isolated from mouse pancreatic beta-cells maintained in tissue culture. 2. The ability of diazoxide and ADP to increase KATP channel activity declined with time following patch excision and no stimulation was observed after 15-40 min. 3. Activation of KATP channels by ADP required the presence of intracellular Mg2+. The stimulatory effect of ADP was mimicked by AMP but only in the presence of ATP. Replacement of ATP with the non-hydrolysable analogue beta, gamma-methylene ATP did not interfere with the ability of ADP to stimulate KATP channel activity. By contrast, enhancement of KATP channel activity was critically dependent on hydrolysable ADP and no stimulation was observed after substitution of alpha,beta-methylene ADP for standard ADP. 4. The ability of diazoxide to enhance KATP channel activity was dependent on the presence of both internal Mg2+ and ATP. Diazoxide stimulation of KATP channel activity was not observed after substitution of beta,gamma-methylene ATP for ATP. However, in the presence of ADP, at a concentration which in itself had no stimulatory action (10 microM), diazoxide was stimulatory also in the presence of the stable ATP analogue. 5. The stimulatory action of diazoxide on KATP channel activity in the presence of ATP was markedly enhanced by intracellular ADP. This potentiating effect of ADP was not reproduced by the stable analogue alpha,beta-methylene ADP and was conditional on the presence of intracellular Mg2+. A similar enhancement of channel activity was also observed with AMP (0.1 mM). In the absence of ATP, diazoxide was still capable of stimulating channel activity provided ADP was present. This effect was not reproduced by AMP. 6. In both nucleotide-free solution and in the presence of 0.1 mM ATP, the distribution of the KATP channel open times were described by a single exponential with a time constant of approximately 20 ms. Addition of ADP or diazoxide resulted in the appearance of a second component with a time constant of > 100 ms which comprised 40-70% of the total number of events. Under the latter experimental conditions, the open probability of the channel increased more than fivefold relative to that observed in the presence of ATP alone.(ABSTRACT TRUNCATED AT 400 WORDS)
This article has been cited by other articles:
|
|
 |
|
  N. M. Doliba, S. L. Wehrli, M. Z. Vatamaniuk, W. Qin, C. W. Buettger, H. W. Collins, and F. M. Matschinsky Metabolic and ionic coupling factors in amino acid-stimulated insulin release in pancreatic beta-HC9 cells Am J Physiol Endocrinol Metab, June 1, 2007; 292(6): E1507 - E1519. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. I. Tarasov, C. A.J. Girard, and F. M. Ashcroft ATP Sensitivity of the ATP-Sensitive K+ Channel in Intact and Permeabilized Pancreatic {beta}-Cells Diabetes, September 1, 2006; 55(9): 2446 - 2454. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. E. Fridlyand, L. Ma, and L. H. Philipson Adenine nucleotide regulation in pancreatic {beta}-cells: modeling of ATP/ADP-Ca2+ interactions Am J Physiol Endocrinol Metab, November 1, 2005; 289(5): E839 - E848. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Wang, J. Wu, L. Li, F. Chen, R. Wang, and C. Jiang Hypercapnic Acidosis Activates KATP Channels in Vascular Smooth Muscles Circ. Res., June 13, 2003; 92(11): 1225 - 1232. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Dabrowski, F. M. Ashcroft, R. Ashfield, P. Lebrun, B. Pirotte, J. Egebjerg, J. Bondo Hansen, and P. Wahl The Novel Diazoxide Analog 3-Isopropylamino-7-Methoxy-4H-1,2,4-Benzothiadiazine 1,1-Dioxide Is a Selective Kir6.2/SUR1 Channel Opener Diabetes, June 1, 2002; 51(6): 1896 - 1906. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Xu, J. Wu, N. Cui, L. Abdulkadir, R. Wang, J. Mao, L. R. Giwa, S. Chanchevalap, and C. Jiang Distinct Histidine Residues Control the Acid-induced Activation and Inhibition of the Cloned KATP Channel J. Biol. Chem., October 12, 2001; 276(42): 38690 - 38696. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L.-C. Chiou and C.-H. How ATP-Sensitive K+ Channels and Cellular Actions of Morphine in Periaqueductal Gray Slices of Neonatal and Adult Rats J. Pharmacol. Exp. Ther., August 1, 2001; 298(2): 493 - 500. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. D'hahan, H. Jacquet, C. Moreau, P. Catty, and M. Vivaudou A Transmembrane Domain of the Sulfonylurea Receptor Mediates Activation of ATP-Sensitive K+ Channels by K+ Channel Openers Mol. Pharmacol., August 1, 1999; 56(2): 308 - 315. [Abstract] [Full Text]
|
|
|
|
 |
|
 L. Aguilar-Bryan and J. Bryan Molecular Biology of Adenosine Triphosphate-Sensitive Potassium Channels Endocr. Rev., April 1, 1999; 20(2): 101 - 135. [Abstract] [Full Text]
|
|
|
|
|
|
R. Branstrom, I. B. Leibiger, B. Leibiger, B. E. Corkey, P.-O. Berggren, and O. Larsson Long Chain Coenzyme A Esters Activate the Pore-forming Subunit (Kir6.2) of the ATP-regulated Potassium Channel J. Biol. Chem., November 20, 1998; 273(47): 31395 - 31400. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Branstrom, S. Efendic, P.-O. Berggren, and O. Larsson Direct Inhibition of the Pancreatic beta -Cell ATP-regulated Potassium Channel by alpha -Ketoisocaproate J. Biol. Chem., June 5, 1998; 273(23): 14113 - 14118. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. P. Dzeja and A. Terzic Phosphotransfer reactions in the regulation of ATP-sensitive K+ channels FASEB J, May 1, 1998; 12(7): 523 - 529. [Abstract] [Full Text]
|
|
|
|
 |
|
 H. Yokoshiki, M. Sunagawa, T. Seki, and N. Sperelakis ATP-sensitive K+ channels in pancreatic, cardiac, and vascular smooth muscle cells Am J Physiol Cell Physiol, January 1, 1998; 274(1): C25 - C37. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Yokoshiki, Y. Katsube, M. Sunagawa, and N. Sperelakis The Novel Calcium Sensitizer Levosimendan Activates the ATP-Sensitive K+ Channel in Rat Ventricular Cells J. Pharmacol. Exp. Ther., October 1, 1997; 283(1): 375 - 383. [Abstract] [Full Text]
|
|
|
|
|
|
R. Branstrom, B. E. Corkey, P.-O. Berggren, and O. Larsson Evidence for a Unique Long Chain Acyl-CoA Ester Binding Site on the ATP-regulated Potassium Channel in Mouse Pancreatic Beta Cells J. Biol. Chem., July 11, 1997; 272(28): 17390 - 17394. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Elvir-Mairena, A. Jovanovic, L. A. Gomez, A. E. Alekseev, and A. Terzic Reversal of the ATP-liganded State of ATP-sensitive K+ Channels by Adenylate Kinase Activity J. Biol. Chem., December 13, 1996; 271(50): 31903 - 31908. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. K. Olson, W. Schroeder, R. P. Robertson, N. D. Goldberg, and T. F. Walseth Suppression of Adenylate Kinase Catalyzed Phosphotransfer Precedes and Is Associated with Glucose-induced Insulin Secretion in Intact HIT-T15 Cells J. Biol. Chem., July 12, 1996; 271(28): 16544 - 16552. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. J. Zeleznikar and N. D. Goldberg Adenylate Kinase-catalyzed Phosphoryl Transfer Couples ATP Utilization with Its Generation by Glycolysis in Intact Muscle J. Biol. Chem., March 31, 1995; 270(13): 7311 - 7319. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Xu, N. Cui, Z. Yang, J. Wu, L. R. Giwa, L. Abdulkadir, P. Sharma, and C. Jiang Direct Activation of Cloned KATP Channels by Intracellular Acidosis J. Biol. Chem., April 13, 2001; 276(16): 12898 - 12902. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Piao, N. Cui, H. Xu, J. Mao, A. Rojas, R. Wang, L. Abdulkadir, L. Li, J. Wu, and C. Jiang Requirement of Multiple Protein Domains and Residues for Gating KATP Channels by Intracellular pH J. Biol. Chem., September 21, 2001; 276(39): 36673 - 36680. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
