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Khanna S, Bhat A, Mardini M, Tan TC. Left ventricular aneurysm: a rare complication of an acute myocardial infarction in the modern era. Oxf Med Case Reports 2020; 2020:omaa080. [PMID: 32995034 PMCID: PMC7507881 DOI: 10.1093/omcr/omaa080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/25/2020] [Accepted: 07/28/2020] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shaun Khanna
- Department of Cardiology, Blacktown Hospital, Blacktown, New South Wales 2148, Australia
| | - Aditya Bhat
- Department of Cardiology, Blacktown Hospital, Blacktown, New South Wales 2148, Australia
| | - Mahidi Mardini
- Department of Cardiology, Westmead Hospital, Westmead, New South Wales 2145, Australia
| | - Timothy C Tan
- Department of Cardiology, Blacktown Hospital, Blacktown, New South Wales 2148, Australia
- Department of Cardiology, Westmead Hospital, Westmead, New South Wales 2145, Australia
- Western Clinical School, Faculty of Medicine, University of Sydney, New South Wales 2145, Australia
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Thavapalachandran S, Wong D, Mardini M, Tan T. Apical hypertrophic cardiomyopathy with coronary artery disease. Heart Lung Circ 2015. [DOI: 10.1016/j.hlc.2015.06.495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Le TYL, Ashton AW, Mardini M, Stanton PG, Funder JW, Handelsman DJ, Mihailidou AS. Role of androgens in sex differences in cardiac damage during myocardial infarction. Endocrinology 2014; 155:568-75. [PMID: 24424037 DOI: 10.1210/en.2013-1755] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Age-specific incidence of ischemic heart disease in men is higher than in women, although women die more frequently without previous symptoms; the molecular mechanism(s) are poorly understood. Most studies focus on protection by estrogen, with less attention on androgen receptor-mediated androgen actions. Our aim was to determine the role of androgens in the sex differences in cardiac damage during myocardial infarction. Mature age-matched male and female Sprague Dawley rats, intact or surgically gonadectomized (Gx), received testosterone (T) or 17β-estradiol (E2) via subdermal SILASTIC (Dow Corning Corp.) implants; a subset of male rats received dihydrotestosterone. After 21 days, animals were anesthetized, and hearts were excised and subjected to ex vivo regional ischemia-reperfusion (I-R). Hearts from intact males had larger infarcts than those from females following I-R; Gx produced the opposite effect, confirming a role for sex steroids. In Gx males, androgens (dihydrotestosterone, T) and E2 aggravated I-R-induced cardiac damage, whereas in Gx females, T had no effect and E2 reduced infarct area. Increased circulating T levels up-regulated androgen receptor and receptor for advanced glycation end products, which resulted in enhanced apoptosis aggravating cardiac damage in both males and females. In conclusion, our study demonstrates, for the first time, that sex steroids regulate autophagy during myocardial infarction and shows that a novel mechanism of action for androgens during I-R is down-regulation of antiapoptotic protein Bcl-xL (B cell lymphoma-extra large), a key controller for cross talk between autophagy and apoptosis, shifting the balance toward apoptosis and leading to aggravated cardiac damage.
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Affiliation(s)
- Thi Y L Le
- Kolling Institute of Medical Research (T.Y.L.L., A.W.A., M.M., A.S.M.), Royal North Shore Hospital and The University of Sydney; Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital; Division of Perinatal Research (A.W.A.), Royal North Shore Hospital; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South Wales, Australia; Prince Henry's Institute (P.G.S., J.W.F.), Clayton, Victoria, Australia; and Anzac Research Institute (D.J.H.), University of Sydney, Sydney, Australia
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Loan Le TY, Mardini M, Howell VM, Funder JW, Ashton AW, Mihailidou AS. Low-Dose Spironolactone Prevents Apoptosis Repressor With Caspase Recruitment Domain Degradation During Myocardial Infarction. Hypertension 2012; 59:1164-9. [DOI: 10.1161/hypertensionaha.111.190488] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Low-dose mineralocorticoid receptor antagonists reduce morbidity and mortality in patients with heart failure and myocardial infarction, despite normal plasma aldosterone levels. Since apoptosis plays an important role in heart failure and postinfarction left ventricular remodeling, we examined whether low-dose mineralocorticoid receptor antagonists modulate cardiomyocyte death by regulating the apoptosis repressor protein apoptosis repressor with caspase recruitment domain to lessen the extent of apoptosis. Hearts from adult male Sprague-Dawley rats were subjected to regional ischemia followed by reperfusion ex vivo, with mineralocorticoid receptor antagonists added to perfusates before ischemia. Low-dose spironolactone (10 nmol/L) or eplerenone (100 nmol/L) significantly reduced infarct size. Spironolactone also prevented cleavage of the apoptotic chromatin condensation inducer in the nucleus and of the inhibitor of caspase-activated DNAse induced by ischemia-reperfusion, thereby abolishing chromatin condensation and internucleosomal cleavage. Ischemia-reperfusion–induced activation of caspases 2, 3, and 9, but not caspase 8, was prevented by spironolactone, suggesting targeted regulation of the intrinsic pathway. Low-dose spironolactone and eplerenone prevented loss of the apoptosis repressor with the caspase recruitment domain and reduced myocyte death. In H9c2 cells, mineralocorticoid receptor activation by aldosterone resulted in apoptosis repressor with caspase recruitment domain degradation and enhanced apoptosis; these actions were prevented by coadministration of spironolactone. Using a triple lysine mutant we identified that aldosterone enhances posttranscriptional degradation of the apoptosis repressor with a caspase recruitment domain via the ubiquitin-proteasomal pathway. Our data demonstrate that low-dose mineralocorticoid receptor antagonists reduce infarct size and apoptosis in the reperfused myocardium by preventing the apoptosis repressor with caspase recruitment domain degradation.
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Affiliation(s)
- Thi Yen Loan Le
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
| | - Mahidi Mardini
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
| | - Viive M. Howell
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
| | - John W. Funder
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
| | - Anthony W. Ashton
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
| | - Anastasia S. Mihailidou
- From the Department of Cardiology (T.Y.L.L., M.M., A.S.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Cardiovascular and Hormonal Research Laboratory, Cardiology Division (T.Y.L.L., M.M., A.S.M.), Hormone and Cancer Division (V.M.H.), and Division of Perinatal Research (A.W.A.), Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South
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Al-Masri MR, Mardini M. Nutritional and Anti-nutritional Components inSesbania aculeataandKochia indicaat Different Harvest Times. Journal of Applied Animal Research 2011. [DOI: 10.1080/09712119.2008.9706936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Wong VW, Mardini M, Cheung NW, Mihailidou AS. High-dose insulin in experimental myocardial infarction in rabbits: protection against effects of hyperglycaemia. J Diabetes Complications 2011; 25:122-8. [PMID: 20206553 DOI: 10.1016/j.jdiacomp.2010.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 12/20/2009] [Accepted: 01/27/2010] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Hyperglycaemia at the time of acute myocardial infarction (AMI) is a predictor of survival and is associated with increased mortality and morbidity in patients with or without diabetes mellitus. On the other hand, insulin has been shown to reduce myocardial injury in experimental studies but its benefits have not been confirmed in clinical studies. METHODS The isolated perfused heart model was used to examine the direct effect of incremental doses of insulin and varying degrees of hyperglycaemia on infarct size and cardiomyocyte apoptosis in rabbit hearts. The rabbit hearts were subjected to 30-min ischaemia and 2.5-h reperfusion. RESULTS Insulin, given alone just before reperfusion, dramatically reduced infarct size in a dose-dependent manner (75-300 μU/ml) during experimental myocardial infarction (46%±2% to 10.9%±3%, P<.001). Acutely elevated glucose levels (33 mmol/L) induced a significantly greater infarct size and cardiomyocyte apoptosis compared to hearts subjected to normal glucose levels. On the other hand, high-dose insulin (300 μU/ml) given 5 min before reperfusion attenuated the extent of infarction and reduced apoptosis in hearts that were exposed to high glucose levels. CONCLUSION Acutely elevated levels of glucose induced larger infarct area during ischaemia-reperfusion, and this is mediated through proapoptotic pathways. Insulin, when given just before reperfusion, confers cardioprotection in a dose-dependent manner and reverses the detrimental effect of acute hyperglycaemia. High-dose insulin as well as maintaining normoglycaemia remain important factors that improve outcomes following myocardial infarction.
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Affiliation(s)
- Vincent W Wong
- Department of Cardiology, Royal North Shore Hospital, Sydney, NSW 2065, Australia
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Mihailidou AS, Loan Le TY, Mardini M, Funder JW. Glucocorticoids Activate Cardiac Mineralocorticoid Receptors During Experimental Myocardial Infarction. Hypertension 2009; 54:1306-12. [DOI: 10.1161/hypertensionaha.109.136242] [Citation(s) in RCA: 191] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Myocardial ischemia-reperfusion leads to significant changes in redox state, decreased postischemic functional recovery, and cardiomyocyte apoptosis, with development and progression of heart failure. Ischemia-reperfusion in the isolated perfused rat heart has been used as a model of heart failure. Clinically, mineralocorticoid receptor blockade in heart failure decreases morbidity and mortality versus standard care alone. The effects of corticosteroids on infarct area and apoptosis were determined in rat hearts subjected to 30 minutes of ischemia and 2.5 hours of reperfusion. Both aldosterone and cortisol increased infarct area and apoptotic index, an effect half-maximal between 1 and 10 nM and reversed by spironolactone. Dexamethasone and mifepristone aggravated infarct area and apoptotic index, similarly reversed by spironolactone. Spironolactone alone reduced infarct area and apoptotic index below ischemia-reperfusion alone, in hearts from both intact and adrenalectomized rats. The present study shows that cardiac damage is aggravated by activation of mineralocorticoid receptors by aldosterone or cortisol or of glucocorticoid receptors by dexamethasone. Mifepristone unexpectedly acted as a glucocorticoid receptor agonist, for which there are several precedents. Spironolactone protected cardiomyocytes via inverse agonist activity at mineralocorticoid receptors, an effect near maximal at a relatively low dose (10 nM). Spironolactone acts not merely by excluding corticosteroids from mineralocorticoid receptors but as a protective inverse agonist at low concentration. Mineralocorticoid receptor antagonists may, thus, provide an additional therapeutic advantage in unstable angina and acute myocardial infarction.
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Affiliation(s)
- Anastasia S. Mihailidou
- From the Department of Cardiology (A.S.M., T.Y.L.L., M.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney (A.S.M., T.Y.L.L., M.M.), Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South Wales, Australia; Prince Henrys Medical Research Institute (J.W.F.), Clayton, Victoria, Australia
| | - Thi Yen Loan Le
- From the Department of Cardiology (A.S.M., T.Y.L.L., M.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney (A.S.M., T.Y.L.L., M.M.), Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South Wales, Australia; Prince Henrys Medical Research Institute (J.W.F.), Clayton, Victoria, Australia
| | - Mahidi Mardini
- From the Department of Cardiology (A.S.M., T.Y.L.L., M.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney (A.S.M., T.Y.L.L., M.M.), Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South Wales, Australia; Prince Henrys Medical Research Institute (J.W.F.), Clayton, Victoria, Australia
| | - John W. Funder
- From the Department of Cardiology (A.S.M., T.Y.L.L., M.M.), Royal North Shore Hospital, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney (A.S.M., T.Y.L.L., M.M.), Sydney, New South Wales, Australia; Department of Cardiology (M.M.), Westmead Hospital, Sydney, New South Wales, Australia; Prince Henrys Medical Research Institute (J.W.F.), Clayton, Victoria, Australia
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Lee AKY, Mardini M, Ross DL, Denniss R. Factors affecting diurnal variability of ventricular tachyarrhythmias detected by multiprogrammable implantable cardioverter-defibrillators. Heart Lung Circ 2004; 13:256-60. [PMID: 16352204 DOI: 10.1016/j.hlc.2004.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Many cardiovascular events, including ventricular arrhythmias, display diurnal variability with a morning peak, and a less pronounced afternoon peak. Since the advent of multiprogrammable implantable cardioverter-defibrillators (ICDs), it has been possible to analyse ventricular tachyarrhythmic events. This study aims to evaluate the circadian pattern of ventricular tachycardias in patients treated with ICDs and examines whether antiarrhythmic medications affect this pattern. Data recorded from 83 patients' ICDs were manually analysed and events other than ventricular arrhythmias were excluded. There was a morning peak of ventricular arrhythmias at around 9.00 a.m. This peak was maintained in patients with ejection fractions of less than 40% and those whose arrhythmias had cycle lengths of less than 230ms. Beta blockers appeared to have no effect on this morning peak but the peak appeared later with amiodarone.
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Affiliation(s)
- Astin K Y Lee
- Department of Cardiology, Westmead Hospital, Westmead, New South Wales 2145, Australia
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9
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Abstract
Aldosterone elevates Na+/K+/2Cl- cotransporter activity in rabbit cardiomyocytes within 15 min, an effect blocked by K-canrenoate and thus putatively mineralocorticoid receptor mediated. Increased cotransporter activity raises intracellular [Na+] sufficient to produce a secondary increase in Na+-K+ pump activity; when this increase in intracellular [Na+] is prevented, a rapid effect of aldosterone to lower pump activity is seen. Addition of transcription inhibitor actinomycin D did not change basal or aldosterone-induced lowered pump activity, indicating a direct, nongenomic action of aldosterone. We examined a possible role for protein kinase C (PKC) in the rapid nongenomic effects of aldosterone. Single ventricular myocytes and pipette solutions containing 10 mm intracellular [Na+] were used in patch clamp studies to measure Na+-K+ pump activity. Aldosterone lowered pump current, an effect abolished by epsilon PKC (epsilonPKC) inhibition but neither alphaPKC nor scrambled epsilonPKC; addition of epsilonPKC activator peptide mimicked the rapid aldosterone effect. In rabbits chronically infused with aldosterone, the lowered pump current in cardiomyocytes was acutely (< or =15 min) restored by epsilonPKC inhibition. These studies show that rapid effects of aldosterone on Na+-K+ pump activity are nongenomic and specifically epsilonPKC mediated; in addition, such effects may be prolonged (7 d) and long-lived ( approximately 4 h isolated cardiomyocyte preparation time). The rapid, prolonged, long-lived effects can be rapidly (< or =15 min) reversed by epsilonPKC blockade, suggesting a hitherto unrecognized complexity of aldosterone action in the heart and perhaps by extension other tissues.
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Affiliation(s)
- Anastasia S Mihailidou
- Department of Cardiology, Royal North Shore Hospital, Pacific Highway, St. Leonards, Sydney, New South Wales 2065, Australia.
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Mardini M, Fraser T, Mihailidou AS, Rassussen H. Renin angiotension aldosterone antagonists ameliorate cyclosporine induced toxicity. Heart Lung Circ 2003. [DOI: 10.1046/j.1443-9506.2003.03441.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Elevated aldosterone levels induce a spironolactone-inhibitable decrease in cardiac sarcolemmal Na+-K+ pump function. Because pump inhibition has been shown to contribute to myocyte hypertrophy, restoration of Na+-K+ pump function may represent a possible mechanism for the cardioprotective action of mineralocorticoid receptor (MR) blockade. The present study examines whether treatment with the angiotensin type 1 receptor antagonist losartan, with either spironolactone or eplerenone, has additive effects on sarcolemmal Na+-K+ pump activity in hyperaldosteronemia. New Zealand White rabbits were divided into 7 different groups: controls, aldosterone alone, aldosterone plus spironolactone, aldosterone plus eplerenone, aldosterone plus losartan, aldosterone plus losartan and spironolactone, and aldosterone plus losartan and eplerenone. After 7 days, myocytes were isolated by enzymatic digestion. Electrogenic Na+-K+ pump current (I(p)), arising from the 3:2 Na+:K+ exchange ratio, was measured by the whole-cell patch clamp technique. Elevated aldosterone levels lowered I(p); treatment with losartan reversed aldosterone-induced reduced pump function, as did MR blockade. Coadministration of spironolactone or eplerenone with losartan enhanced the losartan effect on pump function to a level similar to that measured in rabbits given losartan alone in the absence of hyperaldosteronemia. In conclusion, hyperaldosteronemia induces a decrease in I(p) at near physiological levels of intracellular Na+ concentration. Treatment with losartan reverses this aldosterone-induced decrease in pump function, and coadministration with MR antagonists produces an additive effect on pump function, consistent with a beneficial effect of MR blockade in patients with hypertension and congestive heart failure treated with angiotensin type 1 receptor antagonists.
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Mardini M, Mihailidou AS, Wong A, Rasmussen HH. Cyclosporine and FK506 differentially regulate the sarcolemmal Na(+)-K(+) pump. J Pharmacol Exp Ther 2001; 297:804-10. [PMID: 11303073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Cyclosporine A (CsA) and FK506, important immunosuppressants, have been shown to inhibit the enzymatic equivalent of the Na(+)-K(+) pump (Na(+), K(+)-ATPase) in renal tissue. A similar effect in the heart may contribute to the adverse effects of these agents that include calcification, contractile dysfunction, and altered calcium handling. However, inhibition of the pump has not been demonstrated in cardiac myocytes. We isolated single ventricular myocytes from control rabbits and from rabbits administered CsA or FK506 for 1 week. Na(+)-K(+) pump current (I(p)) was measured using the whole-cell patch-clamp technique. When patch pipettes contained Na(+) in a concentration ([Na](pip)) near physiological intracellular levels mean I(p) of cardiac myocytes from rabbits with serum CsA levels within the therapeutic range was significantly lower than mean I(p) of cardiac myocytes from controls. Treatment had no effect on I(p) measured using a [Na](pip) expected to nearly saturate intracellular binding sites. The CsA-induced inhibition of I(p) was dependent on the K(+) concentration in pipette solutions. Mean I(p) in myocytes from rabbits with serum levels of FK506 within the therapeutic range was similar to mean I(p) in myocytes from controls, whereas FK506 in a dose inducing serum levels severalfold above the therapeutic range caused significant pump inhibition. Using ion-sensitive microelectrodes we showed the intracellular Na(+) activity in papillary muscles isolated from rabbits treated with CsA was significantly higher than in papillary muscles from control rabbits, indicating that CsA causes pump inhibition in intact myocytes with a physiological intracellular milieu.
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Affiliation(s)
- M Mardini
- Department of Medicine, University of Sydney, Sydney, New South Wales, Australia
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13
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Abstract
Aldosterone upregulates the Na(+)-K(+) pump in kidney and colon, classical target organs for the hormone. An effect on pump function in the heart is not firmly established. Because the myocardium contains mineralocorticoid receptors, we examined whether aldosterone has an effect on Na(+)-K(+) pump function in cardiac myocytes. Myocytes were isolated from rabbits given aldosterone via osmotic minipumps and from controls. Electrogenic Na(+)-K(+) pump current, arising from the 3:2 Na(+):K(+) exchange ratio, was measured in single myocytes using the whole-cell patch clamp technique. Treatment with aldosterone induced a decrease in pump current measured when myocytes were dialyzed with patch pipette solution containing Na(+) in a concentration of 10 mmol/L, whereas there was no effect measured when the solution contained 80 mmol/L Na(+). Aldosterone had no effect on myocardial Na(+)-K(+) pump concentration evaluated by vanadate-facilitated [(3)H]ouabain binding or by K(+)-dependent paranitrophenylphosphatase activity in crude homogenates. Aldosterone induced an increase in intracellular Na(+) activity. The aldosterone-induced decrease in pump current and increased intracellular Na(+) were prevented by cotreatment with the mineralocorticoid receptor antagonist spironolactone. Our results indicate that hyperaldosteronemia decreases the apparent Na(+) affinity of the Na(+)-K(+) pump, whereas it has no effect on maximal pump capacity.
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Affiliation(s)
- A S Mihailidou
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia
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Halt M, Kastler B, Livolsi A, Mardini M, Willard D, Wackenheim A. [Tetralogy of Fallot: a pre- and postoperative study using magnetic resonance tomography]. ROFO-FORTSCHR RONTG 1991; 154:111-3. [PMID: 1846680 DOI: 10.1055/s-2008-1033093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- M Halt
- Radiologische Abteilung, Universitätsklinik Strasbourg
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Abstract
We studied three families in which patients with the Holt-Oram syndrome (HOS) had various skeletal abnormalities and congenital heart defects. Two patients had absent thumbs and first metacarpals, hypoplastic radii, and atrial and ventricular septal defects. Patient 2 had pulmonary stenosis, an atrial septal defect, and triphalangeal thumbs. A sister had atrial septal defect and abnormalities of the thumbs; two brothers had abnormalities of the thumbs. The mother had unilateral defect of the thumb with a normal heart. The third patient had tetralogy of Fallot and hypoplastic pulmonary artery. In two families the HOS appeared to be the result of new mutations; in one it was transmitted as an autosomal dominant trait.
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Affiliation(s)
- H Najjar
- Department of Pediatrics, King Faisal Hospital and Research Centre, Riyadh, Saudi Arabia
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Beall AC, Guinn GA, Mattox KL, Lawrie GM, Whisennand HS, Feteih N, Heibig J, Fawsy ME, Tabbaa R, Mardini M, DeBakey ME. Thomas G. Orr Memorial Lecture. Cardiovascular surgery in Saudi Arabia. Am J Surg 1981; 142:646-8. [PMID: 7316025 DOI: 10.1016/0002-9610(81)90302-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A program in cardiovascular surgery from Baylor College of Medicine was transplanted halfway around the world to the Kingdom of Saudi Arabia, providing services with results similar to those obtained in more medically advanced areas of the world. In order to do this, however, numerous support services must be in place and functioning efficiently, and there must be a cooperative spirit on the part of all concerned. In this manner it has been possible not only to provide cardiovascular service to the Kingdom, but also to establish a bidirectional training program. It is intended that eventually this program of cardiovascular surgery will be conducted by Saudi nationals.
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DeBakey ME, Beall AC, Feteih N, Guinn GA, Mattox KL, Lawrie GM, Whisennand HH, Mardini M, Fawsy M, Heibig J, Tabba R, Pickard LR. King Faisal Specialist hospital and Research Centre cardiovascular Surgery Unit: progress report after two years. Cardiovasc Res Cent Bull 1980; 18:57-60. [PMID: 7273056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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