1
|
Reichert S, Schepkin V, Kleimaier D, Zöllner FG, Schad LR. Sodium triple quantum MR signal extraction using a single-pulse sequence with single quantum time efficiency. Magn Reson Med 2024; 92:900-915. [PMID: 38650306 DOI: 10.1002/mrm.30107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/25/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE Sodium triple quantum (TQ) signal has been shown to be a valuable biomarker for cell viability. Despite its clinical potential, application of Sodium TQ signal is hindered by complex pulse sequences with long scan times. This study proposes a method to approximate the TQ signal using a single excitation pulse without phase cycling. METHODS The proposed method is based on a single excitation pulse and a comparison of the free induction decay (FID) with the integral of the FID combined with a shifting reconstruction window. The TQ signal is calculated from this FID only. As a proof of concept, the method was also combined with a multi-echo UTE imaging sequence on a 9.4 T preclinical MRI scanner for the possibility of fast TQ MRI. RESULTS The extracted Sodium TQ signals of single-pulse and spin echo FIDs were in close agreement with theory and TQ measurement by traditional three-pulse sequence (TQ time proportional phase increment [TQTPPI)]. For 2%, 4%, and 6% agar samples, the absolute deviations of the maximum TQ signals between SE and theoretical (time proportional phase increment TQTPPI) TQ signals were less than 1.2% (2.4%), and relative deviations were less than 4.6% (6.8%). The impact of multi-compartment systems and noise on the accuracy of the TQ signal was small for simulated data. The systematic error was <3.4% for a single quantum (SQ) SNR of 5 and at maximum <2.5% for a multi-compartment system. The method also showed the potential of fast in vivo SQ and TQ imaging. CONCLUSION Simultaneous SQ and TQ MRI using only a single-pulse sequence and SQ time efficiency has been demonstrated. This may leverage the full potential of the Sodium TQ signal in clinical applications.
Collapse
Affiliation(s)
- Simon Reichert
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Victor Schepkin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, USA
| | - Dennis Kleimaier
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Cooperative Core Facility Animal Scanner ZI, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| |
Collapse
|
2
|
Intracellular Sodium Changes in Cancer Cells Using a Microcavity Array-Based Bioreactor System and Sodium Triple-Quantum MR Signal. Processes (Basel) 2020. [DOI: 10.3390/pr8101267] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The sodium triple-quantum (TQ) magnetic resonance (MR) signal created by interactions of sodium ions with macromolecules has been demonstrated to be a valuable biomarker for cell viability. The aim of this study was to monitor a cellular response using the sodium TQ signal during inhibition of Na/K-ATPase in living cancer cells (HepG2). The cells were dynamically investigated after exposure to 1 mM ouabain or K+-free medium for 60 min using an MR-compatible bioreactor system. An improved TQ time proportional phase incrementation (TQTPPI) pulse sequence with almost four times TQ signal-to-noise ratio (SNR) gain allowed for conducting experiments with 12–14 × 106 cells using a 9.4 T MR scanner. During cell intervention experiments, the sodium TQ signal increased to 138.9 ± 4.1% and 183.4 ± 8.9% for 1 mM ouabain (n = 3) and K+-free medium (n = 3), respectively. During reperfusion with normal medium, the sodium TQ signal further increased to 169.2 ± 5.3% for the ouabain experiment, while it recovered to 128.5 ± 6.8% for the K+-free experiment. These sodium TQ signal increases agree with an influx of sodium ions during Na/K-ATPase inhibition and hence a reduced cell viability. The improved TQ signal detection combined with this MR-compatible bioreactor system provides a capability to investigate the cellular response of a variety of cells using the sodium TQ MR signal.
Collapse
|
3
|
Kleimaier D, Schepkin V, Hu R, Schad LR. Protein conformational changes affect the sodium triple-quantum MR signal. NMR IN BIOMEDICINE 2020; 33:e4367. [PMID: 32656956 DOI: 10.1002/nbm.4367] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
The aim of this study was to investigate possible sodium triple-quantum (TQ) signal dependence on pH variation and protein unfolding which may happen in vivo. The model system, composed of bovine serum albumin (BSA), was investigated over a wide pH range of 0.70 to 13.05 and during urea-induced unfolding. In both experimental series, the sodium and BSA concentration were kept constant so that TQ signal changes solely arose from an environmental change. The experiments were performed using unique potential to detect weak TQ signals by implementing a TQ time proportional phase increment pulse sequence. At a pH of 0.70, in which case the effect of the negatively charged groups was minimized, the minimum TQ percentage relative to single-quantum of 1.34% ± 0.05% was found. An increase of the pH up to 13.05 resulted in an increase of the sodium TQ signal by 225%. Urea-induced unfolding of BSA, without changes in pH, led to a smaller increase in the sodium TQ signal of up to 40%. The state of BSA unfolding was verified by fluorescence microscopy. Results of both experiments were well fitted by sigmoid functions. Both TQ signal increases were in agreement with an increase of the availability of negatively charged groups. The results point to vital contributions of the biochemical environment to the TQ MR signals. The sodium TQ signal in vivo could be a valuable biomarker of cell viability, and therefore possible effects of pH and protein unfolding need to be considered for a proper interpretation of changes in sodium TQ signals.
Collapse
Affiliation(s)
- Dennis Kleimaier
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Victor Schepkin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, USA
| | - Ruomin Hu
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany
| |
Collapse
|
4
|
Finger MA, Cipullo R, Rossi Neto JM, Santos CC, Contreras CA, Chaccur P, Dinkhuysen JJ, Souza R, Dias França JI, Lin‐Wang HT. Donor hypernatremia and smoking addiction contribute to primary graft failure in heart transplantation. Clin Transplant 2019; 33:e13693. [DOI: 10.1111/ctr.13693] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/31/2019] [Accepted: 08/05/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Marco Aurélio Finger
- Department of Clinical Heart Transplantation Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - Reginaldo Cipullo
- Department of Clinical Heart Transplantation Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - João Manoel Rossi Neto
- Department of Clinical Heart Transplantation Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - Carolina Casadei Santos
- Department of Clinical Heart Transplantation Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | | | - Paulo Chaccur
- Department of Cardiothoracic Surgery Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - Jarbas Jakson Dinkhuysen
- Department of Clinical Heart Transplantation Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - Roberta Souza
- Statistic and Epidemiology Laboratory Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - João Italo Dias França
- Statistic and Epidemiology Laboratory Dante Pazzanese Institute of Cardiology São Paulo Brazil
| | - Hui Tzu Lin‐Wang
- Laboratory of Molecular Investigation in Cardiology Dante Pazzanese Institute of Cardiology São Paulo Brazil
| |
Collapse
|
5
|
Kane AE, Howlett SE. Novel cardioprotection strategies for the aged heart: evidence from pre-clinical studies. Clin Exp Pharmacol Physiol 2017; 43:1251-1260. [PMID: 27626269 DOI: 10.1111/1440-1681.12668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 11/30/2022]
Abstract
The incidence of cardiovascular disease is rising as the population ages. This has led to an increase in the need to perform cardiac surgery in older patients. However, aged hearts are particularly susceptible to reperfusion injury following periods of myocardial ischaemia that occur during cardiac surgery. Indeed, older adults experience myocardial dysfunction and reduced survival post-surgery compared to younger people and certain groups, including older women and frail older adults, are at particular risk. This highlights the need to design cardioprotective strategies specifically for the ageing heart. Cardioprotection during surgery is often accomplished by perfusing the heart with chemical arresting agents, known as cardioplegic solutions. New protective strategies have been developed and tested in animal models, where cardioplegic solutions have been modified by changing their temperature, chemical components and/or the frequency of delivery. In addition, drugs designed to activate cardioprotective mechanisms or to inhibit mechanisms involved in injury have been added to improve the efficacy of these solutions. However, most experimental studies have developed and optimized cardioplegic solutions in hearts from younger male animals. This review discusses pre-clinical models used to optimize cardioplegic solutions, with an emphasis on the few studies that have used hearts from older animals. Pharmacologic agents that have been shown to enhance the benefits of cardioplegia in younger hearts and could, in theory, protect vulnerable older hearts are also considered. We emphasize the need to conduct studies in frail older animals of both sexes to facilitate translation of laboratory-based observations to the clinic.
Collapse
Affiliation(s)
- Alice E Kane
- Department of Pharmacology, Dalhousie University, NS, B3H 4R2, Canada
| | - Susan E Howlett
- Department of Pharmacology, Dalhousie University, NS, B3H 4R2, Canada.,Department of Medicine (Geriatric Medicine), Dalhousie University, Halifax, NS, B3H 4R2, Canada.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
| |
Collapse
|
6
|
Myocardial protection in cardiac surgery: a historical review from the beginning to the current topics. Gen Thorac Cardiovasc Surg 2013; 61:485-96. [PMID: 23877427 DOI: 10.1007/s11748-013-0279-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Indexed: 02/01/2023]
Abstract
Myocardial protection has become an essential adjunctive measure in cardiac surgery for a couple of decades, because since the 1950s, the methods of cardioprotection (cardioplegic solutions and related procedures) have been improved by the mechanism of myocardial ischemia/reperfusion-induced damage being unveiled through the untiring efforts of researchers and clinicians. The concept of myocardial protection in cardiac surgery was proposed along with introduction of hypothermic crystalloid potassium cardioplegia in the beginning and has been diversified by pharmacological additives, blood cardioplegia, temperature modulation (warm; tepid), retrograde cardioplegia, controlled reperfusion, integrated cardioplegia, and pre-and postconditioning. This historical review summarized experimental and clinical studies dealing with the methods and results of myocardial protection in cardiac surgery, introducing the newly developed concepts for the last decade and the current topics.
Collapse
|
7
|
Abstract
The transmembrane sodium gradient is essential for both excitability of the cardiac cell and the regulation of the cytoplasmic concentrations of Ca and protons. In addition, movements of Na across the mitochondrial membrane affect matrix protons and calcium. In the first part of the review, we discuss the most important pathways responsible for sarcolemmal and mitochondrial sodium movements. The bulk of the review considers the changes of intracellular Na concentration ([Na(+)](i)) that occur in disease, specifically, ischemia, reperfusion, and heart failure. We review evidence implicating the increase of intracellular sodium to either increased influx of sodium (via either sodium channels or sodium/hydrogen exchange) or, alternatively, to decreased efflux on the Na/K pump. Although much has been learned about sodium regulation in the heart, there are still many unanswered questions, particularly concerning mitochondrial Na regulation.
Collapse
Affiliation(s)
- Elizabeth Murphy
- Translational Medicine Branch, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892, USA.
| | | |
Collapse
|
8
|
Murphy E, Allen DG. Why did the NHE inhibitor clinical trials fail? J Mol Cell Cardiol 2009; 46:137-41. [PMID: 19027021 PMCID: PMC2661870 DOI: 10.1016/j.yjmcc.2008.09.715] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 09/16/2008] [Accepted: 09/18/2008] [Indexed: 11/25/2022]
Affiliation(s)
- Elizabeth Murphy
- National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA.
| | | |
Collapse
|
9
|
Murphy E, Steenbergen C. Ion transport and energetics during cell death and protection. Physiology (Bethesda) 2008; 23:115-23. [PMID: 18400694 DOI: 10.1152/physiol.00044.2007] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During ischemia, ATP and phosphocreatine (PCr) decline, whereas intracellular hydrogen ion, intracellular sodium (Na(+)), calcium (Ca(2+)), and magnesium (Mg(2+)) concentrations all rise. If the ischemia is relatively short and there is little irreversible injury (cell death), PCr, pH, Na(+), Mg(2+), and Ca(2+) all recovery quickly on reperfusion. ATP recovery can take up to 24 h because of loss of adenine base from the cell and the need for de novo synthesis. There are correlative data showing that a sustained rise in Ca(2+) during ischemia and/or lack of recovery during reperfusion is associated with irreversible cell injury. Interventions that reduce the rise in Ca(2+) during ischemia and reperfusion have been shown to reduce cell death. Therefore, a better understanding of the mechanisms responsible for the rise in Ca(2+) during ischemia and early reperfusion could have important therapeutic implications. This review will discuss mechanisms involved in alterations in ions and high energy phosphate metabolites in perfused or intact heart during ischemia and reperfusion.
Collapse
Affiliation(s)
- Elizabeth Murphy
- National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA.
| | | |
Collapse
|
10
|
Anderson SE, Liu H, Beyschau A, Cala PM. Effects of cold cardioplegia on pH, Na, and Ca in newborn rabbit hearts. Am J Physiol Heart Circ Physiol 2006; 290:H1090-7. [PMID: 16227341 DOI: 10.1152/ajpheart.00776.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many studies suggest myocardial ischemia-reperfusion (I/R) injury results largely from cytosolic proton (Hi)-stimulated increases in cytosolic Na (Nai), which cause Na/Ca exchange-mediated increases in cytosolic Ca concentration ([Ca]i). Because cold, crystalloid cardioplegia (CCC) limits [H]i, we tested the hypothesis that in newborn hearts, CCC diminishes Hi, Nai, and Cai accumulation during I/R to limit injury. NMR measured intracellular pH (pHi), Nai, [Ca]i, and ATP in isolated Langendorff-perfused newborn rabbit hearts. The control ischemia protocol was 30 min for baseline perfusion, 40 min for global ischemia, and 40 min for reperfusion, all at 37°C. CCC protocols were the same, except that ice-cold CCC was infused for 5 min before ischemia and heart temperature was lowered to 12°C during ischemia. Normal potassium CCC solution (NKCCC) was identical to the control perfusate, except for temperature; the high potassium (HKCCC) was identical to NKCCC, except that an additional 11 mmol/l KCl was substituted isosmotically for NaCl. NKCCC and HKCCC were not significantly different for any measurement. The following were different ( P < 0.05). End-ischemia pHi was higher in the CCC than in the control group. Similarly, CCC limited increases in Nai during I/R. End-ischemia Nai values (in meq/kg dry wt) were 115 ± 16 in the control group, 49 ± 13 in the NKCCC group, and 37 ± 12 in the HKCCC group. CCC also improved [Ca]i recovery during reperfusion. After 40 min of reperfusion, [Ca]i values (in nmol/l) were 302 ± 50 in the control group, 145 ± 13 in the NKCCC group, and 182 ± 19 in the HKCCC group. CCC limited ATP depletion during ischemia and improved recovery of ATP and left ventricular developed pressure and decreased creatine kinase release during reperfusion. Surprisingly, CCC did not significantly limit [Ca]i during ischemia. The latter is explained as the result of Ca release from intracellular buffers on cooling.
Collapse
Affiliation(s)
- Steven E Anderson
- Department of Human Physiology, University of California, 1 Shields Ave., Davis, California 95616-8644, USA.
| | | | | | | |
Collapse
|
11
|
Mukherjee R, Yarbrough WM, Reese ES, Leiser JS, Sample JA, Mingoia JT, Hardin AE, Stroud RE, McLean JE, Hendrick JW, Spinale FG. Myocyte contractility with caspase inhibition and simulated hyperkalemic cardioplegic arrest. Ann Thorac Surg 2004; 77:1684-9; discussion 1689-90. [PMID: 15111166 DOI: 10.1016/j.athoracsur.2003.10.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/08/2003] [Indexed: 10/26/2022]
Abstract
BACKGROUND Exposure of left ventricular (LV) myocytes to simulated hyperkalemic cardioplegic arrest (HCA) has been demonstrated to perturb ionic homeostasis and adversely affect myocyte contractility on rewarming. Altered ionic homeostasis can cause cytosolic activation of the caspases. While caspases participate in apoptosis, these proteases can degrade myocyte contractile proteins, and thereby alter myocyte contractility. Accordingly, this study tested the hypothesis that caspase inhibition during HCA would attenuate the degree of myocyte contractile dysfunction upon rewarming, independent of a loss in myocyte viability. METHODS Porcine (n = 8) LV myocytes were isolated and assigned to the following treatment groups: normothermic control: incubation in cell culture media for 2 hours at 37 degrees C; HCA only: incubation for 2 hours in hypothermic HCA solution (4 degrees C, 24 mEq K(+)); or incubation in hypothermic HCA solution supplemented with 10 microM of the caspase inhibitor, z-VAD (z-Val-Ala-Asp-fluoromethyl-ketone, HCA+zVAD). Myocyte viability, assayed as a function of mitochondrial function, was determined to be similar in the normothermic and both HCA groups. RESULTS The HCA caused a significant reduction in myocyte shortening velocity compared with normothermic control values (41 +/- 6 versus 86 +/- 8 microm/s, p < 0.05). The HCA+zVAD group had significantly improved myocyte shortening velocity compared with the HCA only group (63 +/- 7 microm/s, p < 0.05). CONCLUSIONS Independent of changes in viability, caspase inhibition attenuated myocyte contractile dysfunction after HCA and rewarming. Thus, caspase activation during HCA contributes, at least in part, to impaired myocyte contractility with rewarming. Supplementation of HCA with caspase inhibitors may provide a means to preserve myocyte contractile function after cardioplegic arrest.
Collapse
Affiliation(s)
- Rupak Mukherjee
- Division of Cardiothoracic Surgery Research, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Corvera JS, Zhao ZQ, Schmarkey LS, Katzmark SL, Budde JM, Morris CD, Ehring T, Guyton RA, Vinten-Johansen J. Optimal dose and mode of delivery of Na+/H+ exchange-1 inhibitor are critical for reducing postsurgical ischemia-reperfusion injury. Ann Thorac Surg 2003; 76:1614-22. [PMID: 14602297 DOI: 10.1016/s0003-4975(03)00958-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND In clinical trials, perioperative intravenous Na(+)/H(+) exchange isoform-1 (NHE1) inhibitors were only moderately effective in high-risk patients undergoing surgical reperfusion (GUARDIAN trial). However, effective myocardial concentrations of NHE1 inhibitor may not have been achieved by parenteral administration alone. We tested the hypothesis that increasing doses of NHE1 inhibitor EMD 87580 ((2-methyl-4,5-di-(methylsulfonyl)-benzoyl)-guanidine) delivered in blood cardioplegia (BCP) and by parenteral route at reperfusion reduce myocardial injury after surgical reperfusion of evolving infarction. METHODS Twenty-six anesthetized dogs underwent 75 minutes of left anterior descending coronary artery occlusion, followed by cardiopulmonary bypass and 60 minutes of arrest with multidose 10 degrees C BCP. In the control group (n = 8), BCP was not supplemented. In the three EMD-BCP groups, BCP was supplemented with 10 micromol/L EMD 87580 (EMD-10, n = 5), 20 micromol/L EMD 87580 (EMD-20, n = 5), or 20 micromol/L EMD 87580 combined with an immediate reperfusion bolus (5 mg/kg intravenously) (EMD-20R, n = 8). The left anterior descending coronary artery occlusion was released just before the second infusion of BCP. Reperfusion continued for 120 minutes after discontinuation of cardiopulmonary bypass. RESULTS Postischemic systolic and diastolic function in the area at risk was dyskinetic in all groups. Infarct size (percentage of area at risk) was not significantly reduced in the EMD-10 (26.2% +/- 3.6%) and EMD-20 (22.5% +/- 2.4%) groups versus control (30.7% +/- 2.4%); however, infarct size was significantly reduced in the EMD-20R group (16.1% +/- 2.8%, p = 0.003). Edema in the area at risk in the EMD-10 (81.1% +/- 0.5% water content), EMD-20 (81.7% +/- 0.3%), and EMD-20R (81.9% +/- 0.3%) groups was less than in controls (83.2% +/- 0.2%), (p < 0.056). Neutrophil accumulation (myeloperoxidase activity) in postischemic area-at-risk myocardium was less in the EMD-20R group versus the control group (5.3 +/- 0.7 versus 8.7 +/- 1.4 absorbance units x min(-1) x g(-1); p = 0.05), which suggests an attenuated postischemic inflammatory response. CONCLUSIONS Optimal delivery of NHE1 inhibitor to the heart through combined cardioplegia and parenteral routes significantly attenuates myocardial injury after surgical reperfusion of regional ischemia. Timing, dose, and mode of delivery of NHE1 inhibitors are important to their efficacy.
Collapse
Affiliation(s)
- Joel S Corvera
- Cardiothoracic Research Laboratory, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Camara AKS, An J, Chen Q, Novalija E, Varadarajan SG, Schelling P, Stowe DF. Na+/H+ exchange inhibition with cardioplegia reduces cytosolic [Ca2+] and myocardial damage after cold ischemia. J Cardiovasc Pharmacol 2003; 41:686-98. [PMID: 12717098 DOI: 10.1097/00005344-200305000-00004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cold cardioplegia protects against reperfusion damage. Blocking Na+/H+ exchange may be as protective as cardioplegia by improving the left ventricular pressure (LVP)-[Ca2+] relationship after cold ischemia. In guinea pig isolated hearts subjected to cold ischemia (4 h, 17 degrees C) and reperfusion, the cardioprotective effects of a Krebs-Ringer (KR) solution, a cardioplegia solution, a KR solution containing the Na+/H+ exchange inhibitor eniporide (1 microM), and a cardioplegia solution containing eniporide were compared. Treatments were given before and initially after cold ischemia. Systolic and diastolic [Ca2+] were calculated from indo-1 fluorescence transients recorded at the LV free wall. During ischemia, diastolic [Ca2+] increased in each group but more so in the KR group. Peak systolic and diastolic [Ca2+] on initial reperfusion were highest after KR and smallest after cardioplegia + eniporide. After reperfusion, systolic-diastolic LVP (% of baseline) and infarct size (%), respectively, were KR, 47 +/- 3%, 37 +/- 4%; cardioplegia, 71 +/- 5%*, 20 +/- 2.2%*; KR + eniporide, 73 +/- 5%*, 11 +/- 3%* dagger; and cardioplegia + eniporide 77 +/- 3%*, 10 +/- 1.4%* dagger (*P </= 0.05 vs KR; dagger P </= 0.05 vs cardioplegia). Ca2+ overload was reduced in each treated group, and most in the cardioplegia + eniporide group, and was associated with the improved function. Inhibition of Na+/H+ exchange was as effective as cardioplegia in restoring function and better than cardioplegia in reducing infarct size after hypothermic ischemia. The combination of cardioplegia and Na+/H+ exchange inhibition did not produce additive protective effects but caused a larger decrease in Ca2+ loading.
Collapse
Affiliation(s)
- Amadou K S Camara
- Anesthesiology Research Laboratories, Department of Anesthesiology, Cardiovascular Research Center, The Medical College of Wisconsin, Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA
| | | | | | | | | | | | | |
Collapse
|
14
|
Cox CS, Allen SJ, Sauer H, Laine GA. Improved myocardial function using a Na+/H+ exchanger inhibitor during cardioplegic arrest and cardiopulmonary bypass. Chest 2003; 123:187-94. [PMID: 12527621 DOI: 10.1378/chest.123.1.187] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
INTRODUCTION We have demonstrated that a component of post-cardiopulmonary bypass (CPB)/cardioplegic arrest (CPA) myocardial dysfunction is related to myocardial edema. Myocardial ischemia/reperfusion that occurs with CPB/CPA activates the Na(+)/H(+) exchanger to normalize intracellular pH, with intracellular Na(+) (and water) accumulation. We hypothesized that Na(+)/H(+) exchanger inhibition with a selective inhibitor (EMD 87580) would decrease myocardial edema and improve myocardial performance after CPB/CPA. METHODS Anesthetized dogs (n = 14) were instrumented with myocardial ultrasonic crystals, and left ventricular (LV) micromanometer, to study myocardial function. Myocardial tissue water (MWC) was determined using microgravimetry. Treated animals (n = 5) received EMD 87580 (5 mg/kg IV pretreatment and 10 mol/L cardioplegia); control animals (n = 9) received a saline vehicle. After baseline, hypothermic CPB/CPA was initiated for 2 h, followed by reperfusion/rewarming for 45 min and separation from CPB. Myocardial function parameters and MWC were measured at 30 min, 60 min, and 120 min after CPB. RESULTS Preload recruitable stroke work did not decrease from baseline in EMD 87580-treated animals, and was significantly greater in EMD 87580-treated animals than control animals at 120 min after CPB. At a similar LV end-diastolic volume, the maximal rate of rise of LV pressure (dp/dtMAX) was significantly decreased from baseline at all time points in control animals, and unchanged in EMD 87580-treated animals. MWC increased with CPB/CPA in both groups, with no difference between groups. There was no difference in - dp/dtMAX or slope of the end-diastolic pressure-volume relationship. CONCLUSION Na(+)/H(+) exchanger inhibition improves systolic but not diastolic function after CPB/CPA. This is not due to a reduction in MWC.
Collapse
Affiliation(s)
- Charles S Cox
- Department of Surgery, Center for Microvascular and Lymphatic Studies at the University of Texas-Houston, Medical School, Houston, TX, USA.
| | | | | | | |
Collapse
|
15
|
Muraki S, Morris CD, Budde JM, Zhao ZQ, Guyton RA, Vinten-Johansen J. Blood cardioplegia supplementation with the sodium-hydrogen ion exchange inhibitor cariporide to attenuate infarct size and coronary artery endothelial dysfunction after severe regional ischemia in a canine model. J Thorac Cardiovasc Surg 2003; 125:155-64. [PMID: 12538999 DOI: 10.1067/mtc.2003.65] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Activation of the sodium-hydrogen ion exchange mechanism results in accumulation of intracellular calcium through the sodium-calcium ion antiport mechanism. Administration of a sodium-hydrogen ion exchange inhibitor before or during ischemia attenuates myocardial ischemia and reperfusion injury. However, the cardioprotection exerted by sodium-hydrogen ion exchange inhibitors as adjuncts to cardioplegia without perioperative administration has not been tested in a model of surgical reperfusion of acute coronary occlusion with cardiopulmonary bypass. This study tested the hypothesis that sodium-hydrogen ion exchange inhibitor-supplemented blood cardioplegia would reduce postcardioplegia injury after severe regional ischemia. METHODS In anesthetized open-chest dogs, the left anterior descending coronary artery was occluded for 75 minutes, after which total cardiopulmonary bypass was initiated. After crossclamping, cold (4 degrees C) antegrade blood cardioplegia was delivered every 20 minutes for a total of 60 minutes of cardioplegic arrest. In 8 dogs, the blood cardioplegic solution was unsupplemented (vehicle group), whereas in 8 others the solution was supplemented with the sodium-hydrogen ion exchange inhibitor cariporide (10 micro mol/L, cariporide group). RESULTS In the in vitro studies, the direct effects of cariporide on neutrophil function were determined. Isolated canine neutrophils were stimulated by platelet activating factor. Cariporide attenuated superoxide anion production in a concentration-dependent manner, with no appreciable effect at 10 micro mol/L (the concentration used in blood cardioplegia) and a peak effect at 100 micro mol/L. In the in vivo cardiopulmonary bypass model, infarct size was significantly (P <.05) smaller in the cariporide group than in the vehicle group (22.4% +/- 3.5% vs 40.1% +/- 5.1% of area at risk), although there were no group differences in postischemic regional wall motion after 2 hours of reperfusion (0.1% +/- 0.9% vs -0.2% +/- 0.3% systolic shortening). Transmural myocardial edema in the area at risk was significantly decreased in the cariporide group (80.6% +/- 0.5%) relative to the vehicle group (83.1% +/- 0.6%). Myeloperoxidase activity in the area at risk, an index of neutrophil accumulation, was significantly lower in the cariporide group than in the vehicle group (4.7 +/- 0.9 absorbence units/[min. g tissue] vs 10.3 +/- 2.3 absorbence units/[min. g tissue]). In isolated postischemic left anterior descending coronary artery rings, maximum relaxation in response to the endothelium-dependent vasodilator acetylcholine was significantly greater in the cariporide group than in the vehicle group (77.5% +/- 7.4% vs 51.4% +/- 8.0%), whereas smooth muscle relaxation in response to nitroprusside was comparable between groups. CONCLUSION In this canine model, supplementation of blood cardioplegia with cariporide, a sodium-hydrogen ion exchange inhibitor, reduced infarct size, attenuated neutrophil accumulation in the area at risk, and reduced postischemic coronary artery endothelial dysfunction without directly inhibiting neutrophil activity. Cariporide as an adjunct to blood cardioplegia without perioperative administration attenuated surgical ischemia-reperfusion injury in jeopardized myocardium.
Collapse
Affiliation(s)
- Satoshi Muraki
- Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, Ga. 30308-2225, USA
| | | | | | | | | | | |
Collapse
|
16
|
Murphy E, Cross HR, Steenbergen C. Is Na/Ca exchange during ischemia and reperfusion beneficial or detrimental? Ann N Y Acad Sci 2002; 976:421-30. [PMID: 12502591 DOI: 10.1111/j.1749-6632.2002.tb04771.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytosolic calcium increases to approximately 3 micro M after 15 min of global ischemia. Manipulations that attenuate this increase in cytosolic Ca(2+) reduce myocyte death and dysfunction. The increase in cytosolic Ca(2+) during ischemia is dependent on an increase in intracellular Na(+), suggesting a role for Na/Ca exchange. Typical ischemic values for ionized intra- and extracellular Na(+), Ca(2+), and membrane potential are consistent with the Na/Ca exchanger operating near equilibrium during ischemia. Studies were undertaken using hearts from mice that overexpress the Na/Ca exchanger to determine if Na/Ca exchanger overexpression enhances or reduces ischemic injury. These studies suggest that overexpression of the Na/Ca exchanger enhances injury in males, but females are protected by a gender-related mechanism.
Collapse
Affiliation(s)
- Elizabeth Murphy
- Laboratory of Signal Transduction, National Institute for Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
| | | | | |
Collapse
|
17
|
Cox CS, Sauer H, Allen SJ, Buja LM, Laine GA. Sodium/hydrogen-exchanger inhibition during cardioplegic arrest and cardiopulmonary bypass: an experimental study. J Thorac Cardiovasc Surg 2002; 123:959-66. [PMID: 12019382 DOI: 10.1067/mtc.2002.120715] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We sought to determine whether pretreatment with a sodium/hydrogen-exchange inhibitor (EMD 96 785) improves myocardial performance and reduces myocardial edema after cardioplegic arrest and cardiopulmonary bypass. METHODS Anesthetized dogs (n = 13) were instrumented with vascular catheters, myocardial ultrasonic crystals, and left ventricular micromanometers to measure preload recruitable stroke work, maximum rate of pressure rise (positive and negative), and left ventricular end-diastolic volume and pressure. Cardiac output was measured by means of thermodilution. Myocardial tissue water content was determined from sequential biopsy. After baseline measurements, hypothermic (28 degrees C) cardiopulmonary bypass was initiated. Cardioplegic arrest (4 degrees C Bretschneider crystalloid cardioplegic solution) was maintained for 2 hours, followed by reperfusion-rewarming and separation from cardiopulmonary bypass. Preload recruitable stroke work and myocardial tissue water content were measured at 30, 60, and 120 minutes after bypass. EMD 96 785 (3 mg/kg) was given 15 minutes before bypass, and 2 micromol was given in the cardioplegic solution. Control animals received the same volume of saline vehicle. Arterial-coronary sinus lactate difference was similar in both animals receiving EMD 96 785 and control animals, suggesting equivalent myocardial ischemia in each group. RESULTS Myocardial tissue water content increased from baseline in both animals receiving EMD 96 785 and control animals with cardiopulmonary bypass and cardioplegic arrest but was statistically lower in animals receiving EMD 96 785 compared with control animals (range, 1.0%-1.5% lower in animals receiving EMD 96 785). Preload recruitable stroke work decreased from baseline (97 +/- 2 mm Hg) at 30 (59 +/- 6 mm Hg) and 60 (72 +/- 9 mm Hg) minutes after cardiopulmonary bypass and cardioplegic arrest in control animals; preload recruitable stroke work did not decrease from baseline (98 +/- 2 mm Hg) in animals receiving EMD 96 785 and was statistically greater at 30 (88 +/- 5 mm Hg) and 60 (99 +/- 4 mm Hg) minutes after bypass and arrest compared with control animals. CONCLUSIONS Sodium/hydrogen-exchanger inhibition decreases myocardial edema immediately after cardiopulmonary bypass and cardioplegic arrest and improves preload recruitable stroke work. Sodium/hydrogen-exchange inhibition during cardiac procedures with cardiopulmonary bypass and cardioplegic arrest may be a useful adjunct to improve myocardial performance in the immediate postbypass or arrest period.
Collapse
Affiliation(s)
- Charles S Cox
- Department of Surgery and Anesthesiology-Center for Microvascular and Lymphatic Studies, University of Texas-Houston, Medical School, USA.
| | | | | | | | | |
Collapse
|
18
|
Gazmuri RJ, Hoffner E, Kalcheim J, Ho H, Patel M, Ayoub IM, Epstein M, Kingston S, Han Y. Myocardial protection during ventricular fibrillation by reduction of proton-driven sarcolemmal sodium influx. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2001; 137:43-55. [PMID: 11150023 DOI: 10.1067/mlc.2001.111693] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the inhibition of proton-driven sarcolemmal sodium influx ameliorates ischemic injury in the quiescent myocardium, the effects when ventricular fibrillation is present are largely unknown. We used an isolated rat heart model to investigate whether inhibition of the sodium-hydrogen exchanger isoform-1 (with the benzoylguanidine derivatives HOE-694 and cariporide) with or without concomitant inhibition of the sodium-bicarbonate co-transporter (with perfusate buffered with N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid [HEPES]) during ischemia and ventricular fibrillation could ameliorate functional myocardial abnormalities presumed to limit cardiac resuscitability. Ischemic contracture, which typically develops during ventricular fibrillation, was ameliorated by HOE-694 when either a bicarbonate-buffered (20 +/- 7 mm Hg vs 15 +/- 5 mm Hg, P <.05) or a HEPES-buffered (14 +/- 5 mm Hg vs 10 +/- 3 mm Hg, P <.04) perfusate was used. Maximal amelioration occurred when cariporide and HEPES-buffered perfusate were used simultaneously (25 +/- 14 mm Hg vs 11 +/- 3 mm Hg, P <.01), and this was accompanied by lesser leftward shifts of the end-diastolic pressure-volume curves after defibrillation. Intramyocardial sodium increases of 76% during ischemia and ventricular fibrillation (P <.05) were ameliorated by the sodium-influx-limiting interventions. Thus interventions limiting sarcolemmal sodium influx during ischemia and ventricular fibrillation may facilitate successful resuscitation from ventricular fibrillation.
Collapse
Affiliation(s)
- R J Gazmuri
- Medical Service, Section of Critical Care Medicine, North Chicago Veterans Affairs Medical Center, IL 60064, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Schäfer C, Ladilov YV, Schäfer M, Piper HM. Inhibition of NHE protects reoxygenated cardiomyocytes independently of anoxic Ca(2+) overload and acidosis. Am J Physiol Heart Circ Physiol 2000; 279:H2143-50. [PMID: 11045947 DOI: 10.1152/ajpheart.2000.279.5.h2143] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the question of whether inhibition of the Na(+)/H(+) exchanger (NHE) during ischemia is protective due to reduction of cytosolic Ca(2+) accumulation or enhanced acidosis in cardiomyocytes. Additionally, the role of the Na(+)-HCO(3)(-) symporter (NBS) was investigated. Adult rat cardiomyocytes were exposed to simulated ischemia and reoxygenation. Cytosolic pH [2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)], Ca(2+) (fura 2), Na(+) [sodium-binding benzolfuran isophthatlate (SBFI)], and cell length were measured. NHE was inhibited with 3 micromol/l HOE 642 or 1 micromol/l 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and NBS was inhibited with HEPES buffer. During anoxia in bicarbonate buffer, cells developed acidosis and intracellular Na and Ca (Na(i) and Ca(i), respectively) overload. During reoxygenation cells underwent hypercontracture (44.0 +/- 4.1% of the preanoxic length). During anoxia in bicarbonate buffer, inhibition of NHE had no effect on changes in intracellular pH (pH(i)), Na(i), and Ca(i), but it significantly reduced the reoxygenation-induced hypercontracture (HOE: 61.0 +/- 1.4%, EIPA: 68.2 +/- 1.8%). The sole inhibition of NBS during anoxia was not protective. We conclude that inhibition of NHE during anoxia protects cardiomyocytes against reoxygenation injury independently of cytosolic acidification and Ca(i) overload.
Collapse
Affiliation(s)
- C Schäfer
- Physiologisches Institut, Justus Liebig Universität Giessen, D-35392 Giessen, Germany
| | | | | | | |
Collapse
|
20
|
Schepkin VD, Choy IO, Budinger TF, Young JN, DeCampli WM. Multi-dose crystalloid cardioplegia preserves intracellular sodium homeostasis in myocardium. J Mol Cell Cardiol 1999; 31:1643-51. [PMID: 10471348 DOI: 10.1006/jmcc.1999.1002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The goal of this study was to assess the effect of multi-dose St Thomas' cardioplegia on intracellular sodium homeostasis in a rat heart model. A new magnetic resonance method was applied which enable us to detect intracellular Na changes without chemical shift reagents. Three groups of isolated rat hearts were subjected to 51 min of ischemia and 51 min of reperfusion at 37 degrees C: Group 1-three infusions of St Thomas' cardioplegia every 17 min for 2 min (n=7); Group 2-single-dose infusion of cardioplegia at the beginning of stop-flow ischemia (n=8); and Group 3-clamp ischemia (n=3) without cardioplegia administration. Performance of the heart was assessed by rate-pressure product relative to the pre-ischemic level (RPP). An NMR method was applied which continuously detects the Na(i) concentration in the heart, using the ability of bound sodium to exhibit triple-quantum transitions and the growth of the corresponding signal when sodium ions pass from extracellular to intracellular space. Clamp ischemia without cardioplegia and 50 min of reperfusion left the heart dysfunctional, with Na(i) growth from the pre-ischemic level of 13.9+/-1.2 mM to 34.9+/-1.3 mM and 73. 9+/-1.9 mM at the end of ischemia and reperfusion, respectively. During single-dose cardioplegia the corresponding values for Na(i) were 30.2+/-1 mM and 48.5+/-1.7 mM (RPP=29%). Multiple infusions of cardioplegic solution resulted in a remarkable preservation of the heart's intracellular Na concentration with a non-significant increase in Na(i) during ischemia and only 16.7+/-1 mM, (P=0.01), after subsequent reperfusion (RPP=85%). The time course of Na(i) changes in the rat heart model demonstrates a prominent potential of multi-dose St Thomas' cardioplegia in preserving intracellular sodium homeostasis at 37 degrees C. The growth of Na(i) concentration during ischemia, as an indicator of the viability of the myocytes, can have a prognostic value for the heart's performance during reperfusion.
Collapse
Affiliation(s)
- V D Schepkin
- Center for Functional Imaging, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | | | | | | | | |
Collapse
|