T-state Stabilization of Hemoglobin by Nitric Oxide to Form α-Nitrosyl Heme Causes Constitutive Release of ATP from Human Erythrocytes
Upon hypoxia, erythrocytes utilize hemoglobin (Hb) to trigger acti-vation of glycolysis through its interaction with band 3. This process contributes to maintenance of ATP, a portion of which is released extracellularly to trigger endothelium-dependent vasorelaxation. However, whether the ATP release results either from metabolic activation of the cells secondarily or from direct regulation of the gating through Hb allostery remains unknown. This study aimed to examine if stabilization of T-state Hb could induce steady-state and hypoxia-induced alterations in glycolysis and the ATP release from erythrocytes. Treatment of deoxygenated erythrocytes with a nitric oxide (NO) donor generated α-NO Hb that is stabilized T-state allostery. Under these circumstances, the release of ATP was significantly elevated even under normoxia and not further enhanced upon hypoxia. These events did not coincide with activation of glycolysis of the cells, so far as judged by the fact that intracellular ATP was significantly decreased by the NO treatment. Collectively, the present study suggests that hypoxia-induced ATP release is triggered through mechanisms involving R-T transition of Hb, and the gating process might occur irrespective of hypoxia-responsive regulation of glycolysis.
KeywordsNitric Oxide Electron Spin Resonance Metabolome Analysis Hypoxic Vasodilation Hypoxic Solution
This work was supported by Grant-in-Aid for Creative Scientific Research 17GS0419 from MEXT Japan.
- 2.M. L. Ellsworth, T. Forrester, C. G. Ellis, H. H. Dietrich. The erythrocyte as a regulator of vascular tone. Am. J. Physiol. Heart Circ. Physiol. 269, 2155–2161 (1995).Google Scholar
- 3.K. Yamamoto, T. Sokabe, T. Matsumoto, K. Yoshimura, M. Shibata, N. Ohura, T. Fukuda, T. Sato, K. Sekine, S. Kato, M. Isshiki, T. Fujita, M. Kobayashi, K. Kawamura, H. Masuda, A. Kamiya, J. Ando. Impaired flow-dependent control of vascular tone and remodeling in P2X4-deficient mice. Nat. Med. 12, 133–137 (2006).PubMedCrossRefGoogle Scholar
- 4.J. E. Jagger, R. M. Bateman, M. L. Ellsworth, C. G. Ellis. Role of erythrocyte in regulating local O2 delivery mediated by hemoglobin oxygenation. Am. J. Physiol. Heart Circ. Physiol. 280, 2833–2839 (2001).Google Scholar
- 7.A. Kinoshita, K. Tsukada, T. Soga, T. Hishiki, Y. Ueno, Y. Nakayama, M. Tomita, M. Suematsu. Roles of hemoglobin allostery in hypoxia-induced metabolic alterations in erythrocytes: simulation and its verification by metabolome analysis. J. Biol. Chem. 282, 10731–10741 (2007).PubMedCrossRefGoogle Scholar
- 8.K. Suganuma, K. Tsukada, M. Kashiba, A. Tsuneshige, T. Furukawa, T. Kubota, N. Goda, M. Kitajima, T. Yonetani, M. Suematsu. Erythrocytes with T-state-stabilized hemoglobin as a therapeutic tool for postischemic liver dysfunction. Antioxid. Redox. Signal. 8, 1847–1855 (2006).PubMedCrossRefGoogle Scholar