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Ye W, Patel J, Thede K, Aravindabose V, Wentworth S, Monroe I, Garvin ML, Garvin JL, Packer RK. Acute and chronic temperature dependence of Na +/H + exchange activity of Pimephales promelas gills. Comp Biochem Physiol A Mol Integr Physiol 2021; 257:110975. [PMID: 33974967 DOI: 10.1016/j.cbpa.2021.110975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 05/06/2021] [Accepted: 05/06/2021] [Indexed: 11/27/2022]
Abstract
Na+/H+ exchangers (NHE) mediate at least part of Na+ entry into gill epithelia via Na+/NH4+ exchange. For homeostasis, Na+ entry into and exit via Na+/K+ ATPase from gill epithelia must balance. Na+/K+ ATPase activity is reduced in cold- compared to warm-acclimated freshwater temperate fish. We hypothesized gill NHE activity is greater in warm- than cold-acclimated fish when measured at acclimation temperatures, and NHE activity displays a temperature dependence similar to Na+/K+ ATPase. Since NHE mRNA expression does not differ, we measured the Na+-dependence of pH-induced Na+ fluxes in gill vesicles from warm- and cold-acclimated fathead minnows at 20o and 7 °C, and calculated maximum transport rates (Vmax) and Na+ K1/2s. We also measured NH4+-induced Na+ fluxes and Na+-induced H+ fluxes. In vesicles from warm-acclimated fish, NHE Vmaxs were 278 ± 33 and 149 ± 23 arbitrary unit/s (au/s) and Na+ K1/2s were 12 ± 4 and 6 ± 4 mmol/l when assayed at 20o and 7 °C (p < 0.004), respectively. In vesicles from cold-acclimated fish, Vmaxs were 288 ± 35 and 141 ± 13 au/s and Na+ K1/2s 17 ± 5 and 7 ± 2 mmol/l when assayed at 20o and 7 °C (p < 0.002), respectively. Na+-induced H+ fluxes were 98 ± 8 and 104 ± 26 au/s in warm- and cold-acclimated fish assayed at 20 °C, respectively. Na+/NH4+ exchange was 120 ± 11 and 158 ± 13 au/s in warm- and cold-acclimated fish, respectively. Conclusions: Gill NHE activity was greater in warm- than cold-acclimated fish assayed at acclimation temperatures. The temperature dependence of NHE activity was similar in both groups, but differed from that reported for Na+/K+ ATPase suggesting complex mechanisms to maintain Na+ homeostasis.
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Affiliation(s)
- William Ye
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, United States of America
| | - Jill Patel
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, United States of America; Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH 44106, United States of America
| | - Katrina Thede
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH 44106, United States of America
| | - Varsha Aravindabose
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH 44106, United States of America
| | - Simon Wentworth
- Department of Biological Sciences, George Washington University, 2029 G St N.W., Washington, D.C. 20052, United States of America
| | - Ian Monroe
- Department of Biological Sciences, George Washington University, 2029 G St N.W., Washington, D.C. 20052, United States of America
| | - Matthew L Garvin
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH 44106, United States of America
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, United States of America.
| | - Randall K Packer
- Department of Biological Sciences, George Washington University, 2029 G St N.W., Washington, D.C. 20052, United States of America
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Gilles A, Nagel AM, Madelin G. Multipulse sodium magnetic resonance imaging for multicompartment quantification: Proof-of-concept. Sci Rep 2017; 7:17435. [PMID: 29234043 PMCID: PMC5727256 DOI: 10.1038/s41598-017-17582-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/27/2017] [Indexed: 12/18/2022] Open
Abstract
We present a feasibility study of sodium quantification in a multicompartment model of the brain using sodium (23Na) magnetic resonance imaging. The proposed method is based on a multipulse sequence acquisition and simulation at 7 T, which allows to differentiate the 23Na signals emanating from three compartments in human brain in vivo: intracellular (compartment 1), extracellular (compartment 2), and cerebrospinal fluid (compartment 3). The intracellular sodium concentration C1 and the volume fractions α1, α2, and α3 of all respective three brain compartments can be estimated. Simulations of the sodium spin 3/2 dynamics during a 15-pulse sequence were used to optimize the acquisition sequence by minimizing the correlation between the signal evolutions from the three compartments. The method was first tested on a three-compartment phantom as proof-of-concept. Average values of the 23Na quantifications in four healthy volunteer brains were α1 = 0.54 ± 0.01, α2 = 0.23 ± 0.01, α3 = 1.03 ± 0.01, and C1 = 23 ± 3 mM, which are comparable to the expected physiological values \documentclass[12pt]{minimal}
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\begin{document}$${{\boldsymbol{\alpha }}}_{{\bf{1}}}^{{\boldsymbol{theory}}}$$\end{document}α1theory ∼ 0.6, \documentclass[12pt]{minimal}
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\begin{document}$${{\boldsymbol{\alpha }}}_{{\bf{2}}}^{{\boldsymbol{theory}}}$$\end{document}α2theory ∼ 0.2, \documentclass[12pt]{minimal}
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\begin{document}$${{\boldsymbol{\alpha }}}_{{\bf{3}}}^{{\boldsymbol{theory}}}$$\end{document}α3theory ∼ 1, and \documentclass[12pt]{minimal}
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\begin{document}$${{\boldsymbol{C}}}_{{\bf{1}}}^{{\boldsymbol{theory}}}$$\end{document}C1theory ∼ 10–30 mM. The proposed method may allow a quantitative assessment of the metabolic role of sodium ions in cellular processes and their malfunctions in brain in vivo.
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Affiliation(s)
- Alina Gilles
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, 10016, USA.,Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nuremberg, 91054, Erlangen, Germany
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nuremberg, 91054, Erlangen, Germany
| | - Guillaume Madelin
- Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, 10016, USA.
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Hyder F, Manjura Hoque S. Brain Tumor Diagnostics and Therapeutics with Superparamagnetic Ferrite Nanoparticles. CONTRAST MEDIA & MOLECULAR IMAGING 2017; 2017:6387217. [PMID: 29375280 PMCID: PMC5742516 DOI: 10.1155/2017/6387217] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 09/24/2017] [Indexed: 11/18/2022]
Abstract
Ferrite nanoparticles (F-NPs) can transform both cancer diagnostics and therapeutics. Superparamagnetic F-NPs exhibit high magnetic moment and susceptibility such that in presence of a static magnetic field transverse relaxation rate of water protons for MRI contrast is augmented to locate F-NPs (i.e., diagnostics) and exposed to an alternating magnetic field local temperature is increased to induce tissue necrosis (i.e., thermotherapy). F-NPs are modified by chemical synthesis of mixed spinel ferrites as well as their size, shape, and coating. Purposely designed drug-containing nanoparticles (D-NPs) can slowly deliver drugs (i.e., chemotherapy). Convection-enhanced delivery (CED) of D-NPs with MRI guidance improves glioblastoma multiforme (GBM) treatment. MRI monitors the location of chemotherapy when D-NPs and F-NPs are coadministered with CED. However superparamagnetic field gradients produced by F-NPs complicate MRI readouts (spatial distortions) and MRS (extensive line broadening). Since extracellular pH (pHe) is a cancer hallmark, pHe imaging is needed to screen cancer treatments. Biosensor imaging of redundant deviation in shifts (BIRDS) extrapolates pHe from paramagnetically shifted signals and the pHe accuracy remains unaffected by F-NPs. Hence effect of both chemotherapy and thermotherapy can be monitored (by BIRDS), whereas location of F-NPs is revealed (by MRI). Smarter tethering of nanoparticles and agents will impact GBM theranostics.
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Affiliation(s)
- Fahmeed Hyder
- Magnetic Resonance Research Center, Yale University, New Haven, CT, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - S. Manjura Hoque
- Magnetic Resonance Research Center, Yale University, New Haven, CT, USA
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
- Materials Science Division, Bangladesh Atomic Energy Commission, Dhaka, Bangladesh
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James JR, Gao Y, Soon VC, Topper SM, Babsky A, Bansal N. Controlled radio-frequency hyperthermia using an MR scanner and simultaneous monitoring of temperature and therapy response by (1)H, (23)Na and (31)P magnetic resonance spectroscopy in subcutaneously implanted 9L-gliosarcoma. Int J Hyperthermia 2010; 26:79-90. [PMID: 20100055 DOI: 10.3109/02656730903373509] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A magnetic resonance (MR) technique is developed to produce controlled radio-frequency (RF) hyperthermia (HT) in subcutaneously-implanted 9L-gliosarcoma in Fisher rats using an MR scanner and its components; the scanner is also simultaneously used to monitor the tumour temperature and the metabolic response of the tumour to the therapy. The method uses the (1)H chemical shift of thulium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra-acetic acid (TmDOTA(-)) to monitor temperature. The desired HT temperature is achieved and maintained using a feedback loop mechanism that uses a proportional-integral-derivative controller. The RF HT technique was able to heat the tumour from 33 degrees to 45 degrees C in approximately 10 min and was able to maintain the tumour temperature within +/-0.2 degrees C of the target temperature (45 degrees C). Simultaneous monitoring of the metabolic changes with RF HT showed increases in total tissue and intracellular Na(+) as measured by single-quantum and triple-quantum filtered (23)Na MR spectroscopy (MRS), respectively, and decreases in intra- and extracellular pH and cellular bioenergetics as measured by (31)P MRS. Monitoring of metabolic response in addition to the tumour temperature measurements may serve as a more reliable and early indicator of therapy response. In addition, such measurements during HT treatment will enhance our understanding of the tumour response mechanisms during HT, which may prove valuable in designing methods to improve therapeutic efficiency.
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Affiliation(s)
- Judy R James
- Department of Radiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5181, USA
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Dombrauckas JD, Santarsiero BD, Mesecar AD. Structural basis for tumor pyruvate kinase M2 allosteric regulation and catalysis. Biochemistry 2005; 44:9417-29. [PMID: 15996096 DOI: 10.1021/bi0474923] [Citation(s) in RCA: 306] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Four isozymes of pyruvate kinase are differentially expressed in human tissue. Human pyruvate kinase isozyme M2 (hPKM2) is expressed in early fetal tissues and is progressively replaced by the other three isozymes, M1, R, and L, immediately after birth. In most cancer cells, hPKM2 is once again expressed to promote tumor cell proliferation. Because of its almost ubiquitous presence in cancer cells, hPKM2 has been designated as tumor specific PK-M2, and its presence in human plasma is currently being used as a molecular marker for the diagnosis of various cancers. The X-ray structure of human hPKM2 complexed with Mg(2+), K(+), the inhibitor oxalate, and the allosteric activator fructose 1,6-bisphosphate (FBP) has been determined to a resolution of 2.82 A. The active site of hPKM2 is in a partially closed conformation most likely resulting from a ligand-induced domain closure promoted by the binding of FBP. In all four subunits of the enzyme tetramer, a conserved water molecule is observed on the 2-si face of the prospective enolate and supports the hypothesis that a proton-relay system is acting as the proton donor of the reaction (1). Significant structural differences among the human M2, rabbit muscle M1, and the human R isozymes are observed, especially in the orientation of the FBP-activating loop, which is in a closed conformation when FBP is bound. The structural differences observed between the PK isozymes could potentially be exploited as unique structural templates for the design of allosteric drugs against the disease states associated with the various PK isozymes, especially cancer and nonspherocytic hemolytic anemia.
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Affiliation(s)
- Jill D Dombrauckas
- Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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