Abstract
Calcium channel blocker toxicity has been associated with marked hyperglycemia responsive only to high-dose insulin therapy. The exact mechanism(s) of this induced hyperglycemia has not been clearly delineated. The glucose transporter GLUT1 is expressed in a wide variety of cell types and is largely responsible for a basal level of glucose transport. GLUT1 also is activated by cell stress. The specific purpose of this study was to investigate the effects of the calcium channel blocker verapamil on the glucose uptake activity of GLUT1 in L929 fibroblasts cells. Dose-dependent effects of verapamil on glucose uptake were studied using L929 fibroblast cells with 2-deoxyglucose. Verapamil had a dose-dependent inhibitory effect on both basal and stress-activated transport activity of GLUT1. Basal activity was inhibited 50% by 300 μM verapamil, while 150 μM verapamil completely inhibited the activation induced by the stress of glucose deprivation. These effects were reversible and required verapamil to be present during the stress. Alteration of calcium concentrations by addition of 5 mM CaCl2 or 4 mM EDTA had no effect on verapamil action. This study reveals the unique finding that verapamil has inhibitory effects on the transport activity of GLUT1 independent of its effects on calcium concentrations. The inhibition of GLUT1 may be one of the contributing factors to the hyperglycemia observed in CCB poisoning.
Keywords: Calcium channel blocker, Toxicity, GLUT1, Insulin
Full Text
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Acknowledgment
Special thanks to Dr. Laura Bechtel for her review and critique of the manuscript.
Footnotes
This research was supported by a grant from the University of Virginia, Department of Emergency Medicine Research Fund.
References
- 1.Bronstein AC, Spyker DA, Cantilena LR, Jr, Green JL, Rumack BH, Heard SE. Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 25th Annual Report. Clin Toxicol (Phila) 2008;46(10):927–1057. doi: 10.1080/15563650802559632. [DOI] [PubMed] [Google Scholar]
- 2.Litovitz TL, Felberg L, White S, Klein-Schwartz W. 1995 Annual Report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 1996;14(5):487–537. doi: 10.1016/S0735-6757(96)90160-6. [DOI] [PubMed] [Google Scholar]
- 3.Bechtel LK, Haverstick DM, Holstege CP. Verapamil toxicity dysregulates the phosphatidylinositol 3-kinase pathway. Acad Emerg Med. 2008;15(4):368–374. doi: 10.1111/j.1553-2712.2008.00088.x. [DOI] [PubMed] [Google Scholar]
- 4.Boyer EW, Duic PA, Evans A. Hyperinsulinemia/euglycemia therapy for calcium channel blocker poisoning. Pediatr Emerg Care. 2002;18(1):36–37. doi: 10.1097/00006565-200202000-00012. [DOI] [PubMed] [Google Scholar]
- 5.DeWitt CR, Waksman JC. Pharmacology, pathophysiology and management of calcium channel blocker and beta-blocker toxicity. Toxic Rev. 2004;23(4):223–238. doi: 10.2165/00139709-200423040-00003. [DOI] [PubMed] [Google Scholar]
- 6.Holstege C, Kirk M, Furbee R, Wermuth M. Wide complex dysrhythmia in calcium channel blocker overdose responsive to sodium bicarbonate. J Toxicol Clin Toxicol. 1998;36(5):509. [Google Scholar]
- 7.Ohta M, Nelson J, Nelson D, Meglasson MD, Erecinska M. Effect of Ca++ channel blockers on energy level and stimulated insulin secretion in isolated rat islets of Langerhans. J Pharmacol Exp Ther. 1993;264(1):35–40. [PubMed] [Google Scholar]
- 8.Tanen DA, Ruha AM, Curry SC, Graeme KA, Reagan CG. Hypertonic sodium bicarbonate is effective in the acute management of verapamil toxicity in a swine model. Ann Emerg Med. 2000;36(6):547–553. doi: 10.1067/mem.2000.109509. [DOI] [PubMed] [Google Scholar]
- 9.TenHarmsel A, Holstege CP, Louters LL. High dose insulin reverses verapamil inhibition of glucose uptake in mouse striated muscle (abstract) Ann Emerg Med. 2005;46:S77. doi: 10.1016/j.annemergmed.2005.06.286. [DOI] [Google Scholar]
- 10.Kline JA, Raymond RM, Schroeder JD, Watts JA. The diabetogenic effects of acute verapamil poisoning. Toxicol Appl Pharmacol. 1997;145(2):357–362. doi: 10.1006/taap.1997.8195. [DOI] [PubMed] [Google Scholar]
- 11.Holstege CP, Dobmeier S. Cardiovascular challenges in toxicology. Emerg Med Clin North Am. 2005;23(4):1195–1217. doi: 10.1016/j.emc.2005.07.001. [DOI] [PubMed] [Google Scholar]
- 12.Kline JA, Leonova E, Williams TC, Schroeder JD, Watts JA. Myocardial metabolism during graded intraportal verapamil infusion in awake dogs. J Cardiovasc Pharmacol. 1996;27(5):719–726. doi: 10.1097/00005344-199605000-00015. [DOI] [PubMed] [Google Scholar]
- 13.Levine M, Boyer EW, Pozner CN, Geib AJ, Thomsen T, Mick N, Thomas SH. Assessment of hyperglycemia afte calcium channel blocker overdoses involving diltiazem or verapamil. Crit Care Med. 2007;35(9):2071–2075. doi: 10.1097/01.CCM.0000278916.04569.23. [DOI] [PubMed] [Google Scholar]
- 14.Holstege CP, Eldridge DL, Rowden AK. ECG manifestations: the poisoned patient. Emerg Med Clin North Am. 2006;24(1):159–177. doi: 10.1016/j.emc.2005.08.012. [DOI] [PubMed] [Google Scholar]
- 15.Lheureux PE, Zahir S, Gris M, Derrey AS, Penaloza A. Bench-to-bedside review: hyperinsulinaemia/euglycaemia therapy in the management of overdose of calcium-channel blockers. Crit Care. 2006;10(3):212. doi: 10.1186/cc4938. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Yuan TH, Kerns WP, 2nd, Tomaszewski CA, Ford MD, Kline JA. Insulin-glucose as adjunctive therapy for severe calcium channel antagonist poisoning. J Toxicol Clin Toxicol. 1999;37(4):463–474. doi: 10.1081/CLT-100102437. [DOI] [PubMed] [Google Scholar]
- 17.(2005) Toxicology in ECC. Circulation 112(24 (Suppl I)):126–132
- 18.(2005) Pediatric advanced life support. Circulation 112(24(Suppl I)):167–187
- 19.Zhao FQ, Keating AF. Functional properties and genomics of glucose transporters. Current Genomics. 2007;8(2):113–128. doi: 10.2174/138920207780368187. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Baldwin SA, Barros LF, Griffiths M, et al. Regulation of GLUT1 in response to cellular stress. Biochem Soc Trans. 1997;25(3):954–958. doi: 10.1042/bst0250954. [DOI] [PubMed] [Google Scholar]
- 21.Barnes K, Ingram JC, Porras OH, et al. Activation of GLUT1 by metabolic and osmotic stress: potential involvement of AMP-activated protein kinase (AMPK) J Cell Sci. 2002;115(Pt 11):2433–2442. doi: 10.1242/jcs.115.11.2433. [DOI] [PubMed] [Google Scholar]
- 22.Louters LL, Dyste SG, Frieswyk D, et al. Methylene blue stimulates 2-deoxyglucose uptake in L929 fibroblast cells. Life Sci. 2006;78(6):586–591. doi: 10.1016/j.lfs.2005.05.082. [DOI] [PubMed] [Google Scholar]
- 23.Roelofs B, Tidball A, Lindborg AE, TenHarmsel A, Vander Kooy TO, Louters LL. Acute activation of glucose uptake by glucose deprivation in L929 fibroblast cells. Biochimie. 2006;88(12):1941–1946. doi: 10.1016/j.biochi.2006.08.004. [DOI] [PubMed] [Google Scholar]
- 24.Rubin D, Ismail-Beigi F. Distribution of Glut1 in detergent-resistant membranes (DRMs) and non-DRM domains: effect of treatment with azide. Am J Physiol Cell Physiol. 2003;285(2):C377–383. doi: 10.1152/ajpcell.00060.2003. [DOI] [PubMed] [Google Scholar]
- 25.Shetty M, Loeb JN, Vikstrom K, Ismail-Beigi F. Rapid activation of GLUT-1 glucose transporter following inhibition of oxidative phosphorylation in clone 9 cells. J Biol Chem. 1993;268(23):17225–17232. [PubMed] [Google Scholar]
- 26.Khil LY, Cheon AJ, Chang TS, Moon CK. Effects of calcium on brazilin-induced glucose transport in isolated rat epididymal adipocytes. Biochem Pharmacol. 1997;54(1):97–101. doi: 10.1016/S0006-2952(97)00145-7. [DOI] [PubMed] [Google Scholar]
- 27.Whitehead JP, Molero JC, Clark S, Martin S, Meneilly G, James DE. The role of Ca2+ in insulin-stimulated glucose transport in 3T3-L1 cells. J Biol Chem. 2001;276(30):27816–27824. doi: 10.1074/jbc.M011590200. [DOI] [PubMed] [Google Scholar]
- 28.Cartee GD, Briggs-Tung C, Holloszy JO. Diverse effects of calcium channel blockers on skeletal muscle glucose transport. Am J Physiol. 1992;263(1 Pt 2):R70–75. doi: 10.1152/ajpregu.1992.263.1.R70. [DOI] [PubMed] [Google Scholar]
- 29.Ardizzone TD, Lu XH, Dwyer DS. Calcium-independent inhibition of glucose transport in PC-12 and L6 cells by calcium channel antagonists. Am J Physiol Cell Physiol. 2002;283(2):C579–586. doi: 10.1152/ajpcell.00451.2001. [DOI] [PubMed] [Google Scholar]
- 30.Marette A, Richardson JM, Ramlal T, Balon TW, Vranic M, Pessin JE, Klip A. Abundance, localization, and insulin-induced translocation of glucose transporters in red and white muscle. Am J Physiol Cell Physiol. 1992;263(2PT1):C443–452. doi: 10.1152/ajpcell.1992.263.2.C443. [DOI] [PubMed] [Google Scholar]
- 31.Piper RC, Hess LJ, James DE. Differential sorting of two glucose transporters expressed in insulin-sensitive cells. Am J Physiol Cell Physiol. 1992;260(3Pt1):C570–580. doi: 10.1152/ajpcell.1991.260.3.C570. [DOI] [PubMed] [Google Scholar]
- 32.Liong E, Kong SK, Au KK, et al. Inhibition of glucose uptake and suppression of glucose transporter 1 mRNA expression in L929 cells by tumour necrosis factor-alpha. Life Sci. 1999;65(15):PL215–220. doi: 10.1016/S0024-3205(99)00408-7. [DOI] [PubMed] [Google Scholar]
- 33.Wheeler TJ, Cole D, Hauck MA. Characterization of glucose transport activity reconstituted from heart and other tissues. Biochim Biophys Acta. 1998;1414(1–2):217–230. doi: 10.1016/s0005-2736(98)00170-9. [DOI] [PubMed] [Google Scholar]
- 34.Herbert DN, Carruthers A. Glucose transporter oligomeric structure determines transport function: reversible redox-dependent interconversion of tetrameric and dimeric GLUT1. J Biol Chem. 1992;267(33):23829–23838. [PubMed] [Google Scholar]