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Wang J, Papanicolaou K, Tryon R, Sangalang J, Salazar B, Suarez-Pierre A, Dong J, Lee A, Larson E, Holmes S, O’Rourke B, Nichols C, Lawton J. Kir1.1 and SUR1 are not implicated as subunits of an adenosine triphosphate-sensitive potassium channel involved in diazoxide cardioprotection. JTCVS OPEN 2023; 15:231-241. [PMID: 37808059 PMCID: PMC10556815 DOI: 10.1016/j.xjon.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/29/2023] [Accepted: 06/06/2023] [Indexed: 10/10/2023]
Abstract
Objective The adenosine triphosphate-sensitive potassium channel opener diazoxide mimics ischemic preconditioning and is cardioprotective. Clarification of diazoxide's site and mechanism of action could lead to targeted pharmacologic therapies for patients undergoing cardiac surgery. Several mitochondrial candidate proteins have been investigated as potential adenosine triphosphate-sensitive potassium channel components. Renal outer medullary potassium (Kir1.1) and sulfonylurea sensitive regulatory subunit 1 have been suggested as subunits of a mitochondrial adenosine triphosphate-sensitive potassium channel. We hypothesized that pharmacologic blockade or genetic deletion (knockout) of renal outer medullary potassium and sensitive regulatory subunit 1 would result in loss of diazoxide cardioprotection in models of global ischemia with cardioplegia. Methods Myocyte volume and contractility were compared after Tyrode's physiologic solution (20 minutes), stress (hyperkalemic cardioplegia ± diazoxide, ± VU591 (Kir1.1 inhibitor), N = 9 to 23 each, 20 min), and Tyrode's (20 minutes). Isolated mouse (wild-type, sensitive regulatory subunit 1 [-/-], and cardiac knockout renal outer medullary potassium) hearts were given cardioplegia ± diazoxide (N = 9-16 each) before global ischemia (90 minutes) and 30 minutes reperfusion. Left ventricular pressures were compared before and after ischemia. Results Stress (cardioplegia) was associated with reduced myocyte contractility that was prevented by diazoxide. Isolated myocytes were not responsive to diazoxide in the presence of VU591. In isolated hearts, diazoxide improved left ventricular function after prolonged ischemia compared with cardioplegia alone in wild-type and knockout (sensitive regulatory subunit 1 [-/-] and cardiac knockout renal outer medullary potassium) mice. Conclusions Isolated myocyte and heart models may measure independent and separate actions of diazoxide. By definitive genetic deletion, these data indicate that sensitive regulatory subunit 1 and renal outer medullary potassium are not implicated in cardioprotection by diazoxide.
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Affiliation(s)
- Jie Wang
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Kyriakos Papanicolaou
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Md
| | - Robert Tryon
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Mo
| | - Janelle Sangalang
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Ben Salazar
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Md
| | | | - Jie Dong
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Anson Lee
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Emily Larson
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Sari Holmes
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
| | - Brian O’Rourke
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Md
| | - Colin Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Mo
| | - Jennifer Lawton
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University, Baltimore, Md
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Huang Y, Zhou B. Mitochondrial Dysfunction in Cardiac Diseases and Therapeutic Strategies. Biomedicines 2023; 11:biomedicines11051500. [PMID: 37239170 DOI: 10.3390/biomedicines11051500] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Mitochondria are the main site of intracellular synthesis of ATP, which provides energy for various physiological activities of the cell. Cardiomyocytes have a high density of mitochondria and mitochondrial damage is present in a variety of cardiovascular diseases. In this paper, we describe mitochondrial damage in mitochondrial cardiomyopathy, congenital heart disease, coronary heart disease, myocardial ischemia-reperfusion injury, heart failure, and drug-induced cardiotoxicity, in the context of the key roles of mitochondria in cardiac development and homeostasis. Finally, we discuss the main current therapeutic strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction, including pharmacological strategies, gene therapy, mitochondrial replacement therapy, and mitochondrial transplantation. It is hoped that this will provide new ideas for the treatment of cardiovascular diseases.
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Affiliation(s)
- Yafei Huang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing 100037, China
| | - Bingying Zhou
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing 100037, China
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Velez AK, Etchill E, Giuliano K, Kearney S, Jones M, Wang J, Cho B, Brady MB, Dodd‐o J, Meyer JM, Lawton JS. ATP-Sensitive Potassium Channel Opener Diazoxide Reduces Myocardial Stunning in a Porcine Regional With Subsequent Global Ischemia Model. J Am Heart Assoc 2022; 11:e026304. [PMID: 36444837 PMCID: PMC9851454 DOI: 10.1161/jaha.122.026304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background ATP-sensitive potassium channels are inhibited by ATP and open during metabolic stress, providing endogenous myocardial protection. Pharmacologic opening of ATP potassium channels with diazoxide preserves myocardial function following prolonged global ischemia, making it an ideal candidate for use during cardiac surgery. We hypothesized that diazoxide would reduce myocardial stunning after regional ischemia with subsequent prolonged global ischemia, similar to the clinical situation of myocardial ischemia at the time of revascularization. Methods and Results Swine underwent left anterior descending occlusion (30 minutes), followed by 120 minutes global ischemia protected with hyperkalemic cardioplegia±diazoxide (N=6 each), every 20 minutes cardioplegia, then 60 minutes reperfusion. Cardiac output, time to wean from cardiopulmonary bypass, left ventricular (LV) function, caspase-3, and infarct size were compared. Six animals in the diazoxide group separated from bypass by 30 minutes, whereas only 4 animals in the cardioplegia group separated. Diazoxide was associated with shorter but not significant time to wean from bypass (17.5 versus 27.0 minutes; P=0.13), higher, but not significant, cardiac output during reperfusion (2.9 versus 1.5 L/min at 30 minutes; P=0.05), and significantly higher left ventricular ejection fraction at 30 minutes (42.5 versus 15.8%; P<0.01). Linear mixed regression modeling demonstrated greater left ventricular developed pressure (P<0.01) and maximum change in ventricular pressure during isovolumetric contraction (P<0.01) in the diazoxide group at 30 minutes of reperfusion. Conclusions Diazoxide reduces myocardial stunning and facilitates separation from cardiopulmonary bypass in a model that mimics the clinical setting of ongoing myocardial ischemia before revascularization. Diazoxide has the potential to reduce myocardial stunning in the clinical setting.
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Affiliation(s)
- Ana K. Velez
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Eric Etchill
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Katherine Giuliano
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Sean Kearney
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Melissa Jones
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Jie Wang
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
| | - Brian Cho
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care MedicineJohns Hopkins University School of MedicineBaltimoreMD
| | - Mary Beth Brady
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care MedicineJohns Hopkins University School of MedicineBaltimoreMD
| | - Jeffrey Dodd‐o
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care MedicineJohns Hopkins University School of MedicineBaltimoreMD
| | - Joseph M. Meyer
- Division of Cardiology, Department of MedicineJohns Hopkins University School of MedicineBaltimoreMD
| | - Jennifer S. Lawton
- Division of Cardiac Surgery, Department of SurgeryJohns Hopkins University School of MedicineBaltimoreMD
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Suarez-Pierre A, Lui C, Zhou X, Kearney S, Jones M, Wang J, Thomas RP, Gaughan N, Metkus TS, Brady MB, Cho BC, Dodd-O JM, Lawton JS. Diazoxide preserves myocardial function in a swine model of hypothermic cardioplegic arrest and prolonged global ischemia. J Thorac Cardiovasc Surg 2022; 163:e385-e400. [PMID: 32977969 DOI: 10.1016/j.jtcvs.2020.08.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Adenosine triphosphate potassium sensitive channels provide endogenous myocardial protection via coupling of cell membrane potential to myocardial metabolism. Adenosine triphosphate potassium sensitive channel openers, such as diazoxide, mimic ischemic preconditioning, prevent cardiomyocyte swelling, preserve myocyte contractility after stress, and provide diastolic protection. We hypothesize that diazoxide combined with hyperkalemic cardioplegia provides superior myocardial protection compared with cardioplegia alone during prolonged global ischemia in a large animal model. METHODS Twelve pigs were randomized to global ischemia for 2 hours with a single dose of cold blood (4:1) hyperkalemic cardioplegia alone (n = 6) or with diazoxide (500 μmol/L) (n = 6) and reperfused for 1 hour. Cardiac output, myocardial oxygen consumption, left ventricular developed pressure, left ventricular ejection fraction, diastolic function, myocardial troponin, myoglobin, markers of apoptosis, and left ventricular infarct size were compared. RESULTS Four pigs in the cardioplegia alone group could not be weaned from cardiopulmonary bypass. There were no differences in myoglobin, troponin, or apoptosis between groups. Diazoxide preserved cardiac output versus control (74.5 vs 18.4 mL/kg/min, P = .01). Linear mixed regression modeling demonstrated that the addition of diazoxide to cardioplegia preserved left ventricular developed pressure by 36% (95% confidence interval, 9.9-61.5; P < .01), dP/dt max by 41% (95% confidence interval, 14.5-67.5; P < .01), and dP/dt min by 33% (95% confidence interval, 8.9-57.5; P = .01). It was also associated with higher (but not significant) myocardial oxygen consumption (3.7 vs 1.4 mL O2/min, P = .12). CONCLUSIONS Diazoxide preserves systolic and diastolic ventricular function in a large animal model of prolonged global myocardial ischemia. Diazoxide as an adjunct to hyperkalemic cardioplegia may allow safer prolonged ischemic times during increasingly complicated cardiac procedures.
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Affiliation(s)
| | - Cecillia Lui
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Xun Zhou
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Sean Kearney
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Melissa Jones
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Jie Wang
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Rosmi P Thomas
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Natalie Gaughan
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Thomas S Metkus
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Mary B Brady
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Brian C Cho
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Jeffrey M Dodd-O
- Division of Cardiac Anesthesiology, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md
| | - Jennifer S Lawton
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md.
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Fryer ML, Balsam LB. Commentary: Single-dose cardioplegia: Adjusting the brew. J Thorac Cardiovasc Surg 2020; 163:e403-e404. [PMID: 33008577 DOI: 10.1016/j.jtcvs.2020.09.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/05/2020] [Accepted: 09/08/2020] [Indexed: 11/27/2022]
Affiliation(s)
| | - Leora B Balsam
- Division of Cardiac Surgery, UMass Memorial Medical Center, Worcester, Mass.
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Commentary: It's not all in the sauce. J Thorac Cardiovasc Surg 2020; 163:e401. [PMID: 33618887 DOI: 10.1016/j.jtcvs.2020.08.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 11/23/2022]
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Makepeace CM, Suarez-Pierre A, Kanter EM, Schuessler RB, Nichols CG, Lawton JS. Superior diastolic function with K ATP channel opener diazoxide in a novel mouse Langendorff model. J Surg Res 2018; 227:186-193. [PMID: 29804852 DOI: 10.1016/j.jss.2018.02.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 01/11/2018] [Accepted: 02/14/2018] [Indexed: 10/17/2022]
Abstract
BACKGROUND Adenosine triphosphate-sensitive potassium (KATP) channel openers have been found to be cardioprotective in multiple animal models via an unknown mechanism. Mouse models allow genetic manipulation of KATP channel components for the investigation of this mechanism. Mouse Langendorff models using 30 min of global ischemia are known to induce measurable myocardial infarction and injury. Prolongation of global ischemia in a mouse Langendorff model could allow the determination of the mechanisms involved in KATP channel opener cardioprotection. METHODS Mouse hearts (C57BL/6) underwent baseline perfusion with Krebs-Henseleit buffer (30 min), assessment of function using a left ventricular balloon, delivery of test solution, and prolonged global ischemia (90 min). Hearts underwent reperfusion (30 min) and functional assessment. Coronary flow was measured using an inline probe. Test solutions included were as follows: hyperkalemic cardioplegia alone (CPG, n = 11) or with diazoxide (CPG + DZX, n = 12). RESULTS Although the CPG + DZX group had greater percent recovery of developed pressure and coronary flow, this was not statistically significant. Following a mean of 74 min (CPG) and 77 min (CPG + DZX), an additional increase in end-diastolic pressure was noted (plateau), which was significantly higher in the CPG group. Similarly, the end-diastolic pressure (at reperfusion and at the end of experiment) was significantly higher in the CPG group. CONCLUSIONS Prolongation of global ischemia demonstrated added benefit when DZX was added to traditional hyperkalemic CPG. This model will allow the investigation of DZX mechanism of cardioprotection following manipulation of targeted KATP channel components. This model will also allow translation to prolonged ischemic episodes associated with cardiac surgery.
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Affiliation(s)
- Carol M Makepeace
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri
| | - Alejandro Suarez-Pierre
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Evelyn M Kanter
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri
| | - Richard B Schuessler
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University School of Medicine, St. Louis, Missouri
| | - Jennifer S Lawton
- Division of Cardiac Surgery, Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
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Diazoxide reduces local and remote organ damage in a rat model of intestinal ischemia reperfusion. J Surg Res 2018; 225:118-124. [PMID: 29605021 DOI: 10.1016/j.jss.2018.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/18/2017] [Accepted: 01/03/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Intestinal ischemia reperfusion is a common clinical condition that causes functional impairment. Once tight junctions are damaged, barrier function is compromised, and the intestines become a source for entry of bacterial and inflammatory mediators into the circulation, leading to systemic inflammatory response syndrome, multiple organ failure, and death. It is possible that diazoxide could protect the intestines against ischemia reperfusion. The aim of this study is to determine whether diazoxide can provide protection in a rat model of intestinal ischemia reperfusion. METHODS A total of 32 adult male specific pathogen-free Wistar rats were randomized into three groups: a control group, n = 6; a saline group, n = 13; and a diazoxide group, n = 13. The saline and diazoxide groups underwent clamping of the superior mesenteric artery for 1 h, with samples in all the groups being collected 12 h later. RESULTS Intestinal histology showed greater damage in the intestinal ischemia reperfusion groups. mRNA expression of zonula occludens-1 and occludin (tight junction proteins) and interleukin-6 and cyclooxygenase-2 was the highest in the Saline group. The Diazoxide group showed a reduction in aspartate aminotransferase serum levels compared with the other groups. CONCLUSIONS Increased expression of zonula occludens-1, occludin, and cyclooxygenase-2 suggested a greater regenerative effort because of more severe lesions in the saline group. In addition, increased expression of interleukin-6 in the saline group was suggestive of inflammation, indicating that diazoxide had protective effects in the diazoxide group. Reduced aspartate aminotransferase in the diazoxide group suggested liver protection. Diazoxide protects the intestines and liver from intestinal ischemia reperfusion lesions in rats.
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Abstract
Cold cardioplegia is used to induce heart arrest during cardiac surgery. However, endothelial function may be compromised after this procedure. Accordingly, interventions such as adenosine, that mimic the effects of preconditioning, may minimize endothelial injury. Herein, we investigated whether adenosine prevents cold-induced injury to the endothelium. Cultured human cardiac microvascular endothelial cells were treated with adenosine for different durations. Phosphorylation and expression of endothelial nitric oxide synthase (eNOS), p38MAPK, ERK1/2, and p70S6K6 were measured along with nitric oxide (NO) production using diaminofluorescein-2 diacetate (DAF-2DA) probe. Cold-induced injury by hypothermia to 4°C for 45 minutes to mimic conditions of cold cardioplegia during open heart surgery was induced in human cardiac microvascular endothelial cells. Under basal conditions, adenosine stimulated NO production, eNOS phosphorylation at serine 1177 from 5 minutes to 4 hours and inhibited eNOS phosphorylation at threonine 495 from 5 minutes to 6 hours, but increased phosphorylation of ERK1/2, p38MAPK, and p70S6K only after exposure for 5 minutes. Cold-induced injury inhibited NO production and the phosphorylation of the different enzymes. Importantly, adenosine prevented these effects of hypothermic injury. Our data demonstrated that adenosine prevents hypothermic injury to the endothelium by activating ERK1/2, eNOS, p70S6K, and p38MAPK signaling pathways at early time points. These findings also indicated that 5 minutes after administration of adenosine or release of adenosine is an important time window for cardioprotection during cardiac surgery.
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Xie C, Hu J, Motloch LJ, Karam BS, Akar FG. The Classically Cardioprotective Agent Diazoxide Elicits Arrhythmias in Type 2 Diabetes Mellitus. J Am Coll Cardiol 2015; 66:1144-1156. [PMID: 26337994 DOI: 10.1016/j.jacc.2015.06.1329] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 06/06/2015] [Accepted: 06/23/2015] [Indexed: 01/19/2023]
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is associated with an enhanced propensity for ventricular tachyarrhythmias (VTs) under conditions of metabolic demand. Activation of mitochondrial adenosine triphosphate-sensitive potassium (KATP) channels by low-dose diazoxide (DZX) improves hypoglycemia-related complications, metabolic function, and triglyceride and free fatty acid levels and reverses weight gain in T2DM. OBJECTIVES In this study, we hypothesized that DZX prevents ischemia-mediated arrhythmias in T2DM via its putative cardioprotective and antidiabetic property. METHODS Zucker obese diabetic fatty (ZO) rats (n = 43) with T2DM were studied. Controls consisted of Zucker lean (ZL; n = 13) and normal Sprague-Dawley (SprD; n = 30) rats. High-resolution optical action potential mapping was performed before and during challenge with no-flow ischemia for 12 min. RESULTS Electrophysiological properties were relatively stable in T2DM hearts at baseline. In contrast, ischemia uncovered major differences between groups, because action potential duration (APD) in T2DM failed to undergo progressive adaptation to ischemic challenge. DZX promoted the incidence of arrhythmias, because all DZX-treated T2DM hearts exhibited ischemia-induced VTs that persisted on reperfusion. In contrast, untreated T2DM and controls did not exhibit VT during ischemia. Unlike DZX, pinacidil promoted ischemia-mediated arrhythmias in both control and T2DM hearts. Rapid and spatially heterogeneous shortening of APD preceded the onset of arrhythmias in T2DM. DZX-mediated proarrhythmia in T2DM was not related to changes in the messenger ribonucleic acid expression of Kir6.1, Kir6.2, SUR1A, SUR1B, SUR2A, SUR2B, or ROMK (renal outer medullary potassium channel). CONCLUSIONS Ischemia uncovers a paradoxical resistance of T2DM hearts to APD adaptation. DZX reverses this property, resulting in rapid and heterogeneous APD shortening. This promotes reentrant VT during ischemia. DZX should be avoided in diabetic patients at risk of ischemic events.
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Affiliation(s)
- Chaoqin Xie
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jun Hu
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Lukas J Motloch
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Basil S Karam
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fadi G Akar
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
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Impact of novel intraoperative evaluation for mitral valve regurgitation: the retrograde cardio-protective beating test. Surg Today 2014; 45:1153-9. [PMID: 25366352 DOI: 10.1007/s00595-014-1062-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 08/06/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE The saline injection test is commonly employed during mitral valvuloplasty. However, discrepancies in regurgitation between the naked eye findings during the saline injection test and the postoperative echocardiographic findings have been noted. Here, we describe the new retrograde cardio-protective beating test (RC-beating test) which allows direct transatrial evaluation of the valve in the fully loaded, beating heart under cross-clamping by means of the retrograde perfusion of warm oxygenated blood into the coronary sinus. METHODS From January 2006 to June 2012, 63 patients (mean age, 59 ± 15 years) with degenerative mitral valve regurgitation underwent mitral valve repair with application of this novel evaluation. RESULTS In 20 of the 63 patients (31.8%), minor residual leaks that were not remarkable in the saline injection test were detected during the RC-beating test and were completely corrected. Almost all patients (n = 61, 96.8%) revealed no mitral regurgitation on intraoperative transesophageal echocardiography. The results of the RC-beating test were satisfactory, and discrepancies were not recognized at all between this evaluation and the postoperative echocardiographic findings. The ultrastructure of the mitochondria showed significant myocardial preservation. CONCLUSION The RC-beating test is a simpler and more accurate evaluation for mitral valve repair than the saline injection test. This novel evaluation enables a safe and more complete mitral valve repair.
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Wang H, Wang B, Normoyle KP, Jackson K, Spitler K, Sharrock MF, Miller CM, Best C, Llano D, Du R. Brain temperature and its fundamental properties: a review for clinical neuroscientists. Front Neurosci 2014; 8:307. [PMID: 25339859 PMCID: PMC4189373 DOI: 10.3389/fnins.2014.00307] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 09/12/2014] [Indexed: 01/13/2023] Open
Abstract
Brain temperature, as an independent therapeutic target variable, has received increasingly intense clinical attention. To date, brain hypothermia represents the most potent neuroprotectant in laboratory studies. Although the impact of brain temperature is prevalent in a number of common human diseases including: head trauma, stroke, multiple sclerosis, epilepsy, mood disorders, headaches, and neurodegenerative disorders, it is evident and well recognized that the therapeutic application of induced hypothermia is limited to a few highly selected clinical conditions such as cardiac arrest and hypoxic ischemic neonatal encephalopathy. Efforts to understand the fundamental aspects of brain temperature regulation are therefore critical for the development of safe, effective, and pragmatic clinical treatments for patients with brain injuries. Although centrally-mediated mechanisms to maintain a stable body temperature are relatively well established, very little is clinically known about brain temperature's spatial and temporal distribution, its physiological and pathological fluctuations, and the mechanism underlying brain thermal homeostasis. The human brain, a metabolically "expensive" organ with intense heat production, is sensitive to fluctuations in temperature with regards to its functional activity and energy efficiency. In this review, we discuss several critical aspects concerning the fundamental properties of brain temperature from a clinical perspective.
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Affiliation(s)
- Huan Wang
- Department of Neurosurgery, Carle Foundation Hospital, University of Illinois College of Medicine at Urbana-ChampaignUrbana, IL, USA
- Thermal Neuroscience Laboratory, Beckman Institute, University of Illinois at Urbana-ChampaignUrbana, IL, USA
| | - Bonnie Wang
- Department of Internal Medicine, Carle Foundation Hospital, University of Illinois College of Medicine at Urbana-ChampaignUrbana, IL, USA
| | - Kieran P. Normoyle
- Department of Internal Medicine, College of Medicine at Urbana-Champaign, University of IllinoisChampaign, Urbana, IL, USA
- Department of Molecular and Integrative Physiology, University of Illinois College of Medicine at Urbana-ChampaignUrbana, IL, USA
| | - Kevin Jackson
- Thermal Neuroscience Laboratory, Beckman Institute, University of Illinois at Urbana-ChampaignUrbana, IL, USA
| | - Kevin Spitler
- Department of Internal Medicine, Carle Foundation Hospital, University of Illinois College of Medicine at Urbana-ChampaignUrbana, IL, USA
| | - Matthew F. Sharrock
- Department of Internal Medicine, College of Medicine at Urbana-Champaign, University of IllinoisChampaign, Urbana, IL, USA
| | - Claire M. Miller
- Department of Internal Medicine, College of Medicine at Urbana-Champaign, University of IllinoisChampaign, Urbana, IL, USA
- Neuroscience Program, University of Illinois at Urbana-ChampaignUrbana, IL, USA
| | - Catherine Best
- Molecular and Cellular Biology, University of Illinois at Urbana-ChampaignUrbana, IL, USA
| | - Daniel Llano
- Thermal Neuroscience Laboratory, Beckman Institute, University of Illinois at Urbana-ChampaignUrbana, IL, USA
- Department of Molecular and Integrative Physiology, University of Illinois College of Medicine at Urbana-ChampaignUrbana, IL, USA
| | - Rose Du
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical SchoolBoston, MA, USA
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Costa JF, Fontes-Carvalho R, Leite-Moreira AF. Myocardial remote ischemic preconditioning: From pathophysiology to clinical application. REVISTA PORTUGUESA DE CARDIOLOGIA (ENGLISH EDITION) 2013. [DOI: 10.1016/j.repce.2013.10.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Costa JF, Fontes-Carvalho R, Leite-Moreira AF. Pré-condicionamento isquémico remoto do miocárdio: dos mecanismos fisiopatológicos à aplicação na prática clínica. Rev Port Cardiol 2013; 32:893-904. [DOI: 10.1016/j.repc.2013.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 02/21/2013] [Indexed: 12/14/2022] Open
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Anastacio MM, Kanter EM, Keith AD, Schuessler RB, Nichols CG, Lawton JS. Inhibition of Succinate Dehydrogenase by Diazoxide Is Independent of the ATP-Sensitive Potassium Channel Subunit Sulfonylurea Type 1 Receptor. J Am Coll Surg 2013; 216:1144-9. [PMID: 23535164 DOI: 10.1016/j.jamcollsurg.2013.01.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 01/03/2013] [Accepted: 01/23/2013] [Indexed: 10/27/2022]
Abstract
BACKGROUND Diazoxide maintains myocyte volume and contractility during stress via an unknown mechanism. The mechanism of action may involve an undefined (genotype unknown) mitochondrial ATP-sensitive potassium channel and is dependent on the ATP-sensitive potassium channel subunit sulfonylurea type 1 receptor (SUR1). The ATP-sensitive potassium channel openers have been shown to inhibit succinate dehydrogenase (SDH) and a gene for a portion of SDH has been found in the SUR intron. Diazoxide may be cardioprotective via inhibition of SDH, which can form part of an ATP-sensitive potassium channel or share its genetic material. This study investigated the role of inhibition of SDH by diazoxide and its relationship to the SUR1 subunit. STUDY DESIGN Mitochondria were isolated from wild-type and SUR1 knockout mice. Succinate dehydrogenase activity was measured by spectrophotometric analysis of 2,6-dichloroindophenol reduction for 20 minutes as the relative change in absorbance over time. Mitochondria were treated with succinate (20 mM), succinate + 1% dimethylsulfoxide, succinate + malonate (8 mM) (competitive inhibitor of SDH), or succinate + diazoxide (100 μM). RESULTS Both malonate and diazoxide inhibit SDH activity in mitochondria of wild-type mice and in mice lacking the SUR1 subunit (p < 0.05 vs control). CONCLUSIONS The ability of DZX to inhibit SDH persists even after deletion of the SUR1 gene. Therefore, the enzyme complex SDH is not dependent on the SUR1 gene. The inhibition of SDH by DZX can play a role in the cardioprotection afforded by DZX; however, this role is independent of the ATP-sensitive potassium channel subunit SUR1.
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Affiliation(s)
- Melissa M Anastacio
- Department of Surgery, Division of Cardiothoracic Surgery, Washington University School of Medicine, St Louis, MO 63110, USA
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Walters AM, Porter GA, Brookes PS. Mitochondria as a drug target in ischemic heart disease and cardiomyopathy. Circ Res 2013; 111:1222-36. [PMID: 23065345 DOI: 10.1161/circresaha.112.265660] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ischemic heart disease is a significant cause of morbidity and mortality in Western society. Although interventions, such as thrombolysis and percutaneous coronary intervention, have proven efficacious in ischemia and reperfusion injury, the underlying pathological process of ischemic heart disease, laboratory studies suggest further protection is possible, and an expansive research effort is aimed at bringing new therapeutic options to the clinic. Mitochondrial dysfunction plays a key role in the pathogenesis of ischemia and reperfusion injury and cardiomyopathy. However, despite promising mitochondria-targeted drugs emerging from the laboratory, very few have successfully completed clinical trials. As such, the mitochondrion is a potential untapped target for new ischemic heart disease and cardiomyopathy therapies. Notably, there are a number of overlapping therapies for both these diseases, and as such novel therapeutic options for one condition may find use in the other. This review summarizes efforts to date in targeting mitochondria for ischemic heart disease and cardiomyopathy therapy and outlines emerging drug targets in this field.
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Affiliation(s)
- Andrew M Walters
- School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY 14642, USA
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Mennander AA, Shalaby A, Oksala N, Leppänen T, Hämäläinen M, Huovinen S, Zhao F, Moilanen E, Tarkka M. Diazoxide may protect endothelial glycocalyx integrity during coronary artery bypass grafting. SCAND CARDIOVASC J 2012; 46:339-44. [DOI: 10.3109/14017431.2012.717303] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Heat shock protein 90 mediates anti-apoptotic effect of diazoxide by preventing the cleavage of Bid in hypothermic preservation rat hearts. J Heart Lung Transplant 2011; 30:928-34. [PMID: 21620734 DOI: 10.1016/j.healun.2011.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 03/11/2011] [Accepted: 04/19/2011] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Successful organ preservation is the premise for clinical organ transplantation. The present study investigated whether heat shock protein 90 (Hsp90) is important in the anti-apoptotic effect of diazoxide in hypothermic preservation rat hearts. METHODS Isolated rat hearts were preserved in Celsior solution, with or without diazoxide, for 3 to 9 hours, followed by 60 minutes of reperfusion. Cell apoptosis was assessed by terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling. The left ventricular developed pressure (LVDP) was recorded. Expression of Hsp90 protein and cleavage of Bid were detected by Western blot and polymerase chain reaction. RESULTS After hypothermic preservation for 3 to 9 hours, the LVDP recovery rate significantly decreased and cardiomyocyte apoptosis index increased in a time-dependent manner. When compared with the 9-hour preservation group, Celsior solution supplemented with diazoxide significantly enhanced the LVDP recovery rate and decreased the apoptosis index. The cleavage of Bid increased after 9 hours of hypothermic preservation, which was inhibited by Celsior solution supplemented with diazoxide. Hypothermic preservation of rat hearts for 9 hours decreased the expression of Hsp90, whereas diazoxide supplementation significantly increased the expression of Hsp90. The Hsp90 inhibitor 17-allylamino-17-demethoxy-geldanamycin inhibited the diazoxide-induced decrease in cleavage of Bid, improvement of cardiac function, and decrease of apoptosis. Hsp90 inhibitor had no effect on the diazoxide-induced increase of total Cx43 protein expression in hearts preserved 9 hours, but inhibited the diazoxide-induced increase of mitochondrial Cx43 protein level. CONCLUSION Hsp90 might mediate diazoxide-induced cardioprotection against apoptosis in hypothermic preservation heart by preventing the cleavage of Bid.
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Charalampopoulos AF, Nikolaou NI. Emerging pharmaceutical therapies in cardiopulmonary resuscitation and post-resuscitation syndrome. Resuscitation 2011; 82:371-7. [DOI: 10.1016/j.resuscitation.2010.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/05/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022]
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Jakob SM, Stanga Z. Perioperative metabolic changes in patients undergoing cardiac surgery. Nutrition 2010; 26:349-53. [PMID: 20053534 DOI: 10.1016/j.nut.2009.07.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 07/21/2009] [Indexed: 01/10/2023]
Abstract
Perioperative metabolic changes in cardiac surgical patients are not only induced by tissue injury and extracorporeal circulation per se: the systemic inflammatory response to surgical trauma and extracorporeal circulation, perioperative hypothermia, cardiovascular and neuroendocrine responses, and drugs and blood products used to maintain cardiovascular function and anesthesia contribute to varying degrees. The pathophysiologic changes include increased oxygen consumption and energy expenditure; increased secretion of adrenocorticotrophic hormone, cortisol, epinephrine, norepinephrine, insulin, and growth hormone; and decreased total tri-iodothyronine levels. Easily measurable metabolic consequences of these changes include hyperglycemia, hyperlactatemia, increased aspartate, glutamate and free fatty acid concentrations, hypokalemia, increased production of inflammatory cytokines, and increased consumption of complement and adhesion molecules. Nutritional risk before elective cardiac surgery-defined as preoperative unintended pathologic weight loss/low amount of food intake in the preceding week or low body mass index-is related to adverse postoperative outcome. Improvements in surgical techniques, anesthesia, and perioperative management have been designed to minimize the stressful stimulus to catabolism, thereby slowing the wasting process to the point where much less nutrition is required to meet metabolic requirements. Early nutrition in cardiac surgery is safe and well tolerated.
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Affiliation(s)
- Stephan M Jakob
- Department of Intensive Care Medicine, Bern University Hospital and University of Bern, Bern, Switzerland.
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