A series of 1,4,7-triazacyclononane based ligands containing one, two, or three methylphosphinate (MP) side-chains has been prepared. The macrocycle with three methylphosphinates, NOTMP, appeared to be a very promising ligand for monitoring MgII in biological samples by 31P NMR spectroscopy. The 31P resonances of the free ligand and the MgII complex were well resolved, in slow exchange, and well downfield of typical tissue phosphate and phosphate ester metabolite resonances. The Kd value of the Mg(NOTMP) complex was 0.35 mM at physiological pH and temperature, a value which is optimal for accurate assessment of free MgII in cells and blood plasma. The latter was confirmed experimentally. Furthermore, the selectivity of NOTMP for MgII over CaII exceeded two orders of magnitude. The Kd values of the MgII complexes were sensitive to pH and temperature. The pH effects could be easily predicted from potentiometric pH titration data. NOTMP is now being used to measure free, uncomplexed MgII in plasma of patients from the cardiac care unit. We have also continued to explore the utility of TmDOTP5- as a NMR shift reagent for resolving intra- and extracellular 23Na signals in vivo. The interaction between Li+, Na+, Cs+, Ca2+, Mg2+ and the shift reagent has been studied by 7Li, 6Li, 23Na and 133Cs multinuclear NMR spectroscopy. The unusually large paramagnetic shifts ( >> 100 ppm) observed in the cation NMR resonances at low alkali metal ion to TmDOTP5- ratios indicated that the cations bind near the 4-fold symmetry axis of the complex. The geometric parameters for the adducts formed between 7Li, 6Li, 23Na and 133Cs cations and TmDOTP5- were obtained from shift and relaxation rate data and compared with those calculated using MMX energy minimization techniques. It was found that the larger Cs+ ion lies closest to the 4-fold axis of symmetry and displays the largest binding constant, suggesting a greater contribution from tetradentate coordinated species. The smaller Li+ ion deviates most from the 4-fold symmetry axis and has a slightly less favorable binding interaction than Cs+ due to a greater contribution from tridentate coordinated species. Na+ lies somewhere between these two extremes and likely averages bidentate coordination. A significant reversal of the 23Na shift upon addition of Ca2+ and Mg2+ indicate that these two divalent cations form very stable 1:1 adducts with TmDOTP5-(logK (Ca2+) ~ 4 and logK (Mg2+) ~ 3).

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR002584-09
Application #
5224169
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
9
Fiscal Year
1996
Total Cost
Indirect Cost
Chiu, Tsuicheng D; Arai, Tatsuya J; Campbell Iii, James et al. (2018) MR-CBCT image-guided system for radiotherapy of orthotopic rat prostate tumors. PLoS One 13:e0198065
Mishkovsky, Mor; Anderson, Brian; Karlsson, Magnus et al. (2017) Measuring glucose cerebral metabolism in the healthy mouse using hyperpolarized 13C magnetic resonance. Sci Rep 7:11719
Moreno, Karlos X; Harrison, Crystal E; Merritt, Matthew E et al. (2017) Hyperpolarized ?-[1-13 C]gluconolactone as a probe of the pentose phosphate pathway. NMR Biomed 30:
Funk, Alexander M; Anderson, Brian L; Wen, Xiaodong et al. (2017) The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose. J Magn Reson 284:86-93
Zhang, Liang; Habib, Amyn A; Zhao, Dawen (2016) Phosphatidylserine-targeted liposome for enhanced glioma-selective imaging. Oncotarget 7:38693-38706
Walker, Christopher M; Merritt, Matthew; Wang, Jian-Xiong et al. (2016) Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents. J Vis Exp :e53607
Wu, Yunkou; Zhang, Shanrong; Soesbe, Todd C et al. (2016) pH imaging of mouse kidneys in vivo using a frequency-dependent paraCEST agent. Magn Reson Med 75:2432-41
Malloy, Craig R; Sherry, A Dean (2016) Biochemical Specificity in Human Cardiac Imaging by 13C Magnetic Resonance Imaging. Circ Res 119:1146-1148
Moss, Lacy R; Mulik, Rohit S; Van Treuren, Tim et al. (2016) Investigation into the distinct subcellular effects of docosahexaenoic acid loaded low-density lipoprotein nanoparticles in normal and malignant murine liver cells. Biochim Biophys Acta 1860:2363-2376
Bastiaansen, Jessica A M; Merritt, Matthew E; Comment, Arnaud (2016) Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-(13)C]butyrate and [1-(13)C]pyruvate. Sci Rep 6:25573

Showing the most recent 10 out of 374 publications