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Swanson WB, Durdan M, Eberle M, Woodbury S, Mauser A, Gregory J, Zhang B, Niemann D, Herremans J, Ma PX, Lahann J, Weivoda M, Mishina Y, Greineder CF. A library of Rhodamine6G-based pH-sensitive fluorescent probes with versatile in vivo and in vitro applications. RSC Chem Biol 2022; 3:748-764. [PMID: 35755193 PMCID: PMC9175114 DOI: 10.1039/d2cb00030j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/24/2022] [Indexed: 01/11/2023] Open
Abstract
Acidic pH is critical to the function of the gastrointestinal system, bone-resorbing osteoclasts, and the endolysosomal compartment of nearly every cell in the body. Non-invasive, real-time fluorescence imaging of acidic microenvironments represents a powerful tool for understanding normal cellular biology, defining mechanisms of disease, and monitoring for therapeutic response. While commercially available pH-sensitive fluorescent probes exist, several limitations hinder their widespread use and potential for biologic application. To address this need, we developed a novel library of pH-sensitive probes based on the highly photostable and water-soluble fluorescent molecule, Rhodamine 6G. We demonstrate versatility in terms of both pH sensitivity (i.e., pK a) and chemical functionality, allowing conjugation to small molecules, proteins, nanoparticles, and regenerative biomaterial scaffold matrices. Furthermore, we show preserved pH-sensitive fluorescence following a variety of forms of covalent functionalization and demonstrate three potential applications, both in vitro and in vivo, for intracellular and extracellular pH sensing. Finally, we develop a computation approach for predicting the pH sensitivity of R6G derivatives, which could be used to expand our library and generate probes with novel properties.
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Affiliation(s)
- W Benton Swanson
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
| | - Margaret Durdan
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Cell and Molecular Biology Program, Medical School, University of Michigan Ann Arbor MI USA
| | - Miranda Eberle
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
- Department of Chemistry, College of Literature, Science and the Arts, University of Michigan Ann Arbor MI USA
| | - Seth Woodbury
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
- Department of Chemistry, College of Literature, Science and the Arts, University of Michigan Ann Arbor MI USA
| | - Ava Mauser
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Biomedical Engineering, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
| | - Jason Gregory
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Chemical Engineering, College of Engineering, University of Michigan Ann Arbor MI USA
| | - Boya Zhang
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Pharmacology, Medical School, University of Michigan Ann Arbor MI USA
| | - David Niemann
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
- Department of Chemistry, College of Literature, Science and the Arts, University of Michigan Ann Arbor MI USA
- Department of Chemical Engineering, College of Engineering, University of Michigan Ann Arbor MI USA
| | - Jacob Herremans
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
- Department of Chemistry, College of Literature, Science and the Arts, University of Michigan Ann Arbor MI USA
| | - Peter X Ma
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
- Department of Biomedical Engineering, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Materials Science and Engineering, College of Engineering, University of Michigan Ann Arbor MI USA
- Macromolecular Science and Engineering Center, College of Engineering, University of Michigan Ann Arbor MI USA
| | - Joerg Lahann
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Biomedical Engineering, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Chemical Engineering, College of Engineering, University of Michigan Ann Arbor MI USA
- Department of Materials Science and Engineering, College of Engineering, University of Michigan Ann Arbor MI USA
- Macromolecular Science and Engineering Center, College of Engineering, University of Michigan Ann Arbor MI USA
| | - Megan Weivoda
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Pharmacology, Medical School, University of Michigan Ann Arbor MI USA
- Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan Ann Arbor MI USA
| | - Yuji Mishina
- Department of Biologic and Materials Science, School of Dentistry, University of Michigan 1011 North University Avenue Ann Arbor MI 48109 USA
| | - Colin F Greineder
- Biointerfaces Institute, College of Engineering and Medical School, University of Michigan Ann Arbor MI USA
- Department of Pharmacology, Medical School, University of Michigan Ann Arbor MI USA
- Department of Emergency Medicine, Medical School, University of Michigan NCRC 2800 Plymouth Road, Bldg #26 Ann Arbor MI 48109 USA
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Cochrane J, Williams BT, Banerjee A, Harken AH, Burke TJ, Cairns CB, Shapiro JI. Ischemic preconditioning attenuates functional, metabolic, and morphologic injury from ischemic acute renal failure in the rat. Ren Fail 1999; 21:135-45. [PMID: 10088174 DOI: 10.3109/08860229909066978] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ischemic preconditioning has been shown to ameliorate injury due to subsequent ischemia in several organs. However, relatively little is known about preconditioning and the kidney. To address this, rats were randomized to control (C, N = 14), 2 min of ischemic preconditioning (P2 N = 10), 3 periods of 2 min of ischemia separated by 5 min periods of reflow (P2,3 N = 7), or three 5 min periods of ischemia separated by 5 min of reflow (P5,3 N = 6) prior to 45 min of bilateral renal ischemia followed by 24 hours of reperfusion. We observed a lower serum creatinine after 24 hours of reflow in P2, P2, 3 but not P5, 3 rats compared with C. Histology was examined in the C and P2, 3 groups and demonstrated less severe injury in the P2, 3 group. To gain insight into the mechanism by which preconditioning ameliorated ischemic injury, we performed near IR spectroscopy and 31P NMR spectroscopy. Based on near IR spectroscopy, the P2, 3 group had closer coupling of cytochrome aa3 redox state with that of hemoglobin during reflow. In the 31P NMR studies, the changes in ATP and pHi were similar during ischemia, but the P2, 3 group recovered ATP and pHi faster than C. These data suggest that ischemic preconditioning may ameliorate ischemic renal injury as assessed by functional, metabolic and morphological methods. The mechanism(s) by which this occurs requires additional study.
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Affiliation(s)
- J Cochrane
- Department of Medicine, Medical College of Ohio, Toledo 43699-0008, USA
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Sotgiu A, Mäder K, Placidi G, Colacicchi S, Ursini CL, Alecci M. pH-sensitive imaging by low-frequency EPR: a model study for biological applications. Phys Med Biol 1998; 43:1921-30. [PMID: 9703055 DOI: 10.1088/0031-9155/43/7/013] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The use of pH-sensitive nitroxides, in conjunction with low-frequency EPR, offers a unique opportunity for non-invasive assessment of pH values (in the range 0 to 14) in living animals. In the present study, we have investigated the potential use of pH-sensitive nitroxide free radicals in conjunction with EPR imaging techniques at low and very low frequencies (280 MHz-2.1 GHz). In particular, we have measured the hyperfine splitting (hfs) of a pH-sensitive probe at three different EPR frequencies: 280 MHz, 1.1 GHz and 2.1 GHz. We have also developed EPR imaging experiments with phantoms simulating in vivo conditions, using pH-sensitive probes at 280 MHz (spatial-spatial) and 1.1 GHz (spectral-spatial). Finally, we discuss the actual sensitivity/resolution limits of the EPR imaging techniques at low frequencies. Practical applications of this method in the biomedical field are suggested for the continuous and non-invasive localization of pH in vivo.
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Affiliation(s)
- A Sotgiu
- Dipartimento di Scienze e Tecnologie Biomediche, Universita' dell'Aquila, Italy.
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Hunjan S, Mason RP, Mehta VD, Kulkarni PV, Aravind S, Arora V, Antich PP. Simultaneous intracellular and extracellular pH measurement in the heart by 19F NMR of 6-fluoropyridoxol. Magn Reson Med 1998; 39:551-6. [PMID: 9543416 DOI: 10.1002/mrm.1910390407] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
6-Fluoropyridoxol (6-FPOL) was evaluated as a simultaneous indicator of intracellular and extracellular pH and, hence, pH gradient in perfused rat hearts. After infusion, 19F NMR spectra rapidly showed two well-resolved peaks assigned to the intracellular and extracellular compartments, and pH was calculated on the basis of chemical shift with respect to a sodium trifluoroacetate standard. To demonstrate use of this molecule, dynamic changes in myocardial pH were assessed with a time resolution of 2 min during respiratory and metabolic alkalosis or acidosis and ischemia. For a typical heart, intracellular pH (pHi) = 7.14+/-0.01 and extracellular pH (pHe) = 7.52+/-0.02. In response to metabolic alkalosis, pHi remained relatively constant and the pH gradient increased. In contrast, respiratory challenge caused a significant increase in pHi. Independent measurements using pH electrodes and 31P NMR confirmed validity of the 19F NMR results.
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Affiliation(s)
- S Hunjan
- Advanced Radiological Sciences, UT Southwestern Medical Center, Dallas, Texas 75235-9058, USA
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Filgueiras CL, Winsborrow B, Ye J, Scott J, Aronov A, Kozlowski P, Shabnavard L, Summers R, Saunders JK, Deslauriers R. A 31p-magnetic resonance study of antegrade and retrograde cerebral perfusion during aortic arch surgery in pigs. J Thorac Cardiovasc Surg 1995; 110:55-62. [PMID: 7609569 DOI: 10.1016/s0022-5223(05)80009-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To evaluate the effect of hypothermic circulatory arrest on brain metabolism, we used 31P-magnetic resonance spectroscopy to monitor brain metabolites in pigs during 2 hours of ischemia and 1 hour of reperfusion. Twenty-eight pigs were divided into five groups. Anesthesia (n = 5) and hypothermic cardiopulmonary bypass groups (n = 5) served as controls. In the circulatory arrest (n = 6), antegrade perfusion (n = 6), and retrograde (n = 6) brain perfusion groups, the bypass flow rate was 60 to 100 ml.kg-1.min-1. In the antegrade group, the brain was perfused via the carotid arteries at a blood flow rate of 180 to 200 ml.min-1 during circulatory arrest at 15 degrees C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml.min-1 during circulatory arrest at 15 degrees C. The intracellular pH was 7.1 +/- 0.1 and 7.3 +/- 0.1 in the anesthesia and hypothermic cardiopulmonary bypass groups, respectively. In the circulatory arrest group, the intracellular pH decreased to 6.2 +/- 0.1 and did not recover to its initial value (7.0 +/- 0.1) during reperfusion (p < 0.05 compared with the value obtained from the control groups at the corresponding time). Inorganic phosphate did not return to its initial level during reperfusion. In three animals in this group, levels of high-energy phosphates, adenosine triphosphate and phosphocreatine, recovered partially but did not reach the levels observed before arrest. In the group receiving antegrade perfusion, cerebral metabolites and intracellular pH were unchanged throughout the protocol. During circulatory arrest in the retrograde perfusion group the intracellular pH decreased to 6.4 +/- 0.1 and recovered fully during reperfusion (7.1 +/- 0.1). High-energy phosphates also returned to their initial levels during reperfusion. These studies show that deep hypothermic circulatory arrest with antegrade brain perfusion provides the best brain protection of the options investigated.
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Affiliation(s)
- C L Filgueiras
- Institute for Biodiagnostics, National Research Coucil, Canada, Winnipeg, Manitoba
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Rossini L, Bernardi M, Concettoni C, De Florio L, Deslauriers R, Moretti V, Piantelli F, Pigini P, Re L, Rossini P. Some approaches to the pharmacology of multisubstrate enzyme systems. Pharmacol Res 1994; 29:313-35. [PMID: 7971684 DOI: 10.1016/1043-6618(94)80054-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Analytical and exploratory in vitro, in situ and in vivo, physio-pharmacotoxicology, from enzymology to population epidemiology, now embraces those approaches that correlate complex dynamic multisubstrate kinetics through conventional and more recent non-invasive quantitative methodologies. Basically, substrates may be classed as pertaining to fundamental energy turnovers (first-order cellular metabolic pathways or networks) and to iso- vs allosteric modulator systems (second-order metabolic control network). Pairs of substrates and cofactors set-up the third-order multienzyme-receptor patterns, which in intact, native in vivo structures establish and maintain the compartmentalized, dynamically superimposed overall coordination of local redox and phosphate potentials. Perturbations of the various levels of the metabolic hierarchy induced by drugs, as well their relaxations, can be readily submitted to non-invasive kinetic analysis. Both indirect and direct titrations of substrate levels, their modelling and statistical ad hoc evaluations of their interrelations can lead to the identification of the multiple sites involved in drug effects as structured at the different orders/levels of concomitant functional variations. Fractal geometries contribute towards defining the space- and time-related events.
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Affiliation(s)
- L Rossini
- Institute of Experimental and Clinical Medicine-Pharmacology, University of Ancona, Italy
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