1
|
van der Hoek S, Mulder DJ, Willemsen AT, Visser T, Heeres A, Slart RH, Elsinga PH, Heerspink HJ, Stevens J. Studying Telmisartan Plasma Exposure, Kidney Distribution, Receptor Occupancy, and Response in Patients With Type 2 Diabetes Using [ 11 C]Telmisartan. Clin Pharmacol Ther 2022; 112:1264-1270. [PMID: 36070078 PMCID: PMC9827889 DOI: 10.1002/cpt.2744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/30/2022] [Indexed: 01/31/2023]
Abstract
The angiotensin receptor blocker telmisartan slows progression of kidney disease in patients with type 2 diabetes (T2D), yet many patients remain at high risk for progressive kidney function loss. The underlying mechanisms for this response variation might be attributed to differences in angiotensin-1 receptor occupancy (RO), resulting from individual variation in plasma drug exposure, tissue drug exposure, and receptor availability. Therefore, we first assessed the relationship between plasma telmisartan exposure and urinary-albumin-to-creatinine-ratio (UACR) in 10 patients with T2D and albuminuria (mean age 66 years, median UACR 297 mg/g) after 4 weeks treatment with 80 mg telmisartan once daily. Increasing telmisartan exposure associated with a larger reduction in UACR (Pearson correlation coefficient (PCC) = -0.64, P = 0.046, median change UACR: -40.1%, 95% confidence interval (CI): -22.9 to -77.4%, mean telmisartan area under the curve (AUC) = 2927.1 ng·hour/mL, 95% CI: 723.0 to 6501.6 ng·hour/mL). Subsequently, we assessed the relation among plasma telmisartan exposure, kidney distribution, and angiotensin-1 RO in five patients with T2D (mean age 60 years, median UACR 72 mg/g) in a separate positron emission tomography imaging study with [11 C]Telmisartan. Individual plasma telmisartan exposure correlated with telmisartan distribution to the kidneys (PCC = 0.976, P = 0.024). A meaningful RO could be calculated in three patients receiving 120 mg oral telmisartan, and although high exposure seems related to higher RO, with AUC0-last of 31, 840, and 274 ng·hour/mL and corresponding RO values 5.5%, 44%, and 59%, this was not significant (P = 0.64). Together these results indicate, for the first time, a relationship among interindividual differences in plasma exposure, kidney tissue distribution, RO, and ultimately UACR response after telmisartan administration.
Collapse
Affiliation(s)
- Sjoukje van der Hoek
- Department of Clinical Pharmacy and PharmacologyUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | - Douwe J. Mulder
- Division of Vascular Medicine, Department of Internal MedicineUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | - Antoon T.M. Willemsen
- Department of Nuclear Medicine and Molecular ImagingUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | | | - Andre Heeres
- SymeresGroningenThe Netherlands,Hanze University of Applied SciencesGroningenThe Netherlands
| | - Riemer H.J.A. Slart
- Department of Nuclear Medicine and Molecular ImagingUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular ImagingUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | - Hiddo J.L. Heerspink
- Department of Clinical Pharmacy and PharmacologyUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| | - Jasper Stevens
- Department of Clinical Pharmacy and PharmacologyUniversity Medical Center Groningen, University of GroningenGroningenThe Netherlands
| |
Collapse
|
2
|
de Souza AMA, Ecelbarger CM, Sandberg K. Caloric Restriction and Cardiovascular Health: the Good, the Bad, and the Renin-Angiotensin System. Physiology (Bethesda) 2021; 36:220-234. [PMID: 34159807 DOI: 10.1152/physiol.00002.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Much excitement exists over the cardioprotective and life-extending effects of caloric restriction (CR). This review integrates population studies with experimental animal research to address the positive and negative impact of mild and severe CR on cardiovascular physiology and pathophysiology, with a particular focus on the renin-angiotensin system (RAS). We also highlight the gaps in knowledge and areas ripe for future physiological research.
Collapse
Affiliation(s)
- Aline M A de Souza
- Division of Nephrology and Hypertension, Department of Medicine, Georgetown University, Washington, District of Columbia
| | - Carolyn M Ecelbarger
- Division of Nephrology and Hypertension, Department of Medicine, Georgetown University, Washington, District of Columbia
| | - Kathryn Sandberg
- Division of Nephrology and Hypertension, Department of Medicine, Georgetown University, Washington, District of Columbia
| |
Collapse
|
3
|
Synthesis and Evaluation of [ 18F]FEtLos and [ 18F]AMBF 3Los as Novel 18F-Labelled Losartan Derivatives for Molecular Imaging of Angiotensin II Type 1 Receptors. Molecules 2020; 25:molecules25081872. [PMID: 32325695 PMCID: PMC7221519 DOI: 10.3390/molecules25081872] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/18/2020] [Accepted: 01/23/2020] [Indexed: 01/13/2023] Open
Abstract
Losartan is widely used in clinics to treat cardiovascular related diseases by selectively blocking the angiotensin II type 1 receptors (AT1Rs), which regulate the renin-angiotensin system (RAS). Therefore, monitoring the physiological and pathological biodistribution of AT1R using positron emission tomography (PET) might be a valuable tool to assess the functionality of RAS. Herein, we describe the synthesis and characterization of two novel losartan derivatives PET tracers, [18F]fluoroethyl-losartan ([18F]FEtLos) and [18F]ammoniomethyltrifluoroborate-losartan ([18F]AMBF3Los). [18F]FEtLos was radiolabeled by 18F-fluoroalkylation of losartan potassium using the prosthetic group 2-[18F]fluoroethyl tosylate; whereas [18F]AMBF3Los was prepared following an one-step 18F-19F isotopic exchange reaction, in an overall yield of 2.7 ± 0.9% and 11 ± 4%, respectively, with high radiochemical purity (>95%). Binding competition assays in AT1R-expressing membranes showed that AMBF3Los presented an almost equivalent binding affinity (Ki 7.9 nM) as the cold reference Losartan (Ki 1.5 nM), unlike FEtLos (Ki 2000 nM). In vitro and in vivo assays showed that [18F]AMBF3Los displayed a good binding affinity for AT1R-overexpressing CHO cells and was able to specifically bind to renal AT1R. Hence, our data demonstrate [18F]AMBF3Los as a new tool for PET imaging of AT1R with possible applications for the diagnosis of cardiovascular, inflammatory and cancer diseases.
Collapse
|
4
|
Molecular imaging of cardiac remodelling after myocardial infarction. Basic Res Cardiol 2018; 113:10. [PMID: 29344827 PMCID: PMC5772148 DOI: 10.1007/s00395-018-0668-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 11/17/2017] [Accepted: 01/08/2018] [Indexed: 02/06/2023]
Abstract
Myocardial infarction and subsequent heart failure is a major health burden associated with significant mortality and morbidity in western societies. The ability of cardiac tissue to recover after myocardial infarction is affected by numerous complex cellular and molecular pathways. Unbalance or failure of these pathways can lead to adverse remodelling of the heart and poor prognosis. Current clinical cardiac imaging modalities assess anatomy, perfusion, function, and viability of the myocardium, yet do not offer any insight into the specific molecular pathways involved in the repair process. Novel imaging techniques allow visualisation of these molecular processes and may have significant diagnostic and prognostic values, which could aid clinical management. Single photon-emission tomography, positron-emission tomography, and magnetic resonance imaging are used to visualise various aspects of these molecular processes. Imaging probes are usually attached to radioisotopes or paramagnetic nanoparticles to specifically target biological processes such as: apoptosis, necrosis, inflammation, angiogenesis, and scar formation. Although the results from preclinical studies are promising, translating this work to a clinical environment in a valuable and cost-effective way is extremely challenging. Extensive evaluation evidence of diagnostic and prognostic values in multi-centre clinical trials is still required.
Collapse
|
5
|
Ismail B, deKemp RA, Hadizad T, Mackasey K, Beanlands RS, DaSilva JN. Decreased renal AT1 receptor binding in rats after subtotal nephrectomy: PET study with [(18)F]FPyKYNE-losartan. EJNMMI Res 2016; 6:55. [PMID: 27339045 PMCID: PMC4919198 DOI: 10.1186/s13550-016-0209-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/14/2016] [Indexed: 01/13/2023] Open
Abstract
Background Significant renal mass reduction induced by 5/6 subtotal nephrectomy (Nx) is associated with a chain of events that culminates in hypertension and chronic kidney disease (CKD). Numerous studies have provided evidence for the role of angiotensin (Ang) II type 1 receptor (AT1R) in the promotion and progression of the disease; however, conflicting results were reported on intrarenal AT1R levels in CKD models. Methods Male Sprague-Dawley rats (n = 26) underwent Nx or sham operations. Animals were scanned at 8–10 weeks post-surgery with PET using the novel AT1R radioligand [18F]FPyKYNE-losartan. Radioligand binding was quantified by kidney-to-blood ratio (KBR), standard uptake value (SUV), and distribution volume (DV). After sacrifice, plasma and kidney Ang II levels were measured. Western blot and 125I-[Sar1, Ile8]Ang II autoradiography were performed to assess AT1R expression. Results At 8–10 weeks post-surgery, Nx rats developed hypertension, elevated plasma creatinine levels, left ventricle hypertrophy, increased myocardial blood flow (MBF), and reduced Ang II levels compared to shams. PET measurements displayed significant decrease in KBR (29 %), SUV (24 %), and DV (22 %) induced by Nx (p < 0.05), and these findings were confirmed by in vitro assays. Conclusions Reduced renal AT1Rs in hypertensive rats measured with [18F]FPyKYNE-losartan PET at 8–10 weeks following Nx support further use of this non-invasive approach in longitudinal studies to better understand the AT1R role in CKD progression.
Collapse
Affiliation(s)
- Basma Ismail
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada
| | - Robert A deKemp
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada
| | - Tayebeh Hadizad
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada
| | - Kumiko Mackasey
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada
| | - Rob S Beanlands
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada
| | - Jean N DaSilva
- National Cardiac PET Centre, University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, K1Y 4W7, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada. .,Department of Radiology, Radio-Oncology and Nuclear Medicine, University of Montreal, University of Montreal Hospital Research Centre (CRCHUM), 900 Rue Saint-Denis, Montréal, Québec, H2X 0A9, Canada.
| |
Collapse
|
6
|
Hachem M, Tiberi M, Ismail B, Hunter CR, Arksey N, Hadizad T, Beanlands RS, deKemp RA, DaSilva JN. Characterization of 18F-FPyKYNE-Losartan for Imaging AT1 Receptors. J Nucl Med 2016; 57:1612-1617. [DOI: 10.2967/jnumed.115.170951] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/11/2016] [Indexed: 12/25/2022] Open
|
7
|
Prigent A, Chaumet-Riffaud P. Clinical problems in renovascular disease and the role of nuclear medicine. Semin Nucl Med 2014; 44:110-22. [PMID: 24484748 DOI: 10.1053/j.semnuclmed.2013.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although renovascular disease remains defined as a stenosis of the main renal artery or its proximal branches (renal artery stenosis [RAS]), its clinical overview has changed dramatically over the last 15-20 years and its management is more controversial than ever before. The clinical problems, not only diagnosis and treatment but also the relative contribution of different pathophysiological mechanisms involved in the progression of kidney disease, have shifted dramatically. This presentation aims to emphasize the paradigm change revisiting the (recent) past focused on renovascular hypertension (RVH) to the current context of preservation or recovery of threatened renal function in patients with progressive atherosclerotic renovascular disease until its last stage of irreversible "ischemic nephropathy." In the past, the foreground was occupied by RVH, a very rare disease, where the activation of the renin-angiotensin-aldosterone system (RAAS) was supposed to play the major, if not only, role in RVH issues. The retrospective RVH diagnosis was established either on the improvement or, more rarely, on the cure of hypertension after revascularization by, most often, a percutaneous transluminal renal angioplasty with or without a stent placement. At this time, captoptril radionuclide renography was an efficient diagnostic tool, because it was a functional (angiotensin-converting enzyme inhibition), noninvasive test aiming to evidence both the RAAS activation and the lateralization (or asymmetry) of renin secretion by the kidney affected by a "hemodynamically significant" RAS. At present, even if captoptril radionuclide renography could be looked upon as the most efficient (and cost effective in selected high-risk patients) noninvasive, functional test to predict the improvement of hypertension after RAS correction, its clinical usefulness is questioned as the randomized, prospective trials failed to demonstrate any significant benefits (either on blood pressure control or on renal function protection) of the revascularization over current antihypertensive therapy. Today many patients with RVH remain undetected for years because they are treated successfully and at low expense with these new blockers of RAAS. In addition to its well-known role in hemodynamics, angiotensin II promotes activations of profibrogenic and inflammatory factors and cells and stimulates reactive oxygen species generation. The "atherosclerotic milieu" itself plays a role in the loss of renal microvessels and defective angiogenesis. After an "adaptative" phase, ischemia eventually develops and induces hypoxia, the substratum of ischemic nephropathy. Because blood oxygen level-dependent MRI may provide an index of oxygen content in vivo, it may be useful to predict renal function outcome after percutaneous transluminal renal angioplasty. New PET tracers, dedicated to assess RAAS receptors, inflammatory cell infiltrates, angiogenesis, and apoptose, would be tested in this context of atherosclerotic renovascular disease.
Collapse
Affiliation(s)
- Alain Prigent
- Service de Biophysique et Médecine Nucléaire, AP-HP Hôpitaux Universitaires Paris-Sud Bicêtre, Paris, France.
| | - Philippe Chaumet-Riffaud
- Service de Biophysique et Médecine Nucléaire, AP-HP Hôpitaux Universitaires Paris-Sud Bicêtre, Paris, France; IR4M UMR8081 CNRS, Université Paris-Sud, Orsay, France
| |
Collapse
|
8
|
Abstract
There is an expanding and exciting repertoire of PET imaging radiotracers for urogenital diseases, particularly in prostate cancer, renal cell cancer, and renal function. Prostate cancer is the most commonly diagnosed cancer in men. With growing therapeutic options for the treatment of metastatic and advanced prostate cancer, improved functional imaging of prostate cancer beyond the limitations of conventional CT and bone scan is becoming increasingly important for both clinical management and drug development. PET radiotracers, apart from ¹⁸F-FDG, for prostate cancer are ¹⁸F-sodium fluoride, ¹¹C-choline, and ¹⁸F-fluorocholine, and (¹¹C-acetate. Other emerging and promising PET radiotracers include a synthetic l-leucine amino acid analogue (anti-¹⁸F-fluorocyclobutane-1-carboxylic acid), dihydrotestosterone analogue (¹⁸F-fluoro-5α-dihydrotestosterone), and prostate-specific membrane antigen-based PET radiotracers (eg, N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-4-¹⁸F-fluorobenzyl-l-cysteine, ⁸⁹Zr-DFO-J591, and ⁶⁸Ga [HBED-CC]). Larger prospective and comparison trials of these PET radiotracers are needed to establish the role of PET/CT in prostate cancer. Although renal cell cancer imaging with FDG-PET/CT is available, it can be limited, especially for detection of the primary tumor. Improved renal cell cancer detection with carbonic anhydrase IX (CAIX)-based antibody (¹²⁴I-girentuximab) and radioimmunotherapy targeting with ¹⁷⁷Lu-cG250 appear promising. Evaluation of renal injury by imaging renal perfusion and function with novel PET radiotracers include p-¹⁸F-fluorohippurate, hippurate m-cyano-p-¹⁸F-fluorohippurate, and rubidium-82 chloride (typically used for myocardial perfusion imaging). Renal receptor imaging of the renal renin-angiotensin system with a variety of selective PET radioligands is also becoming available for clinical translation.
Collapse
Affiliation(s)
- Steve Y Cho
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD
| | - Zsolt Szabo
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, MD.
| |
Collapse
|
9
|
Lautamäki R, Knuuti J, Saraste A. Recent Developments in Imaging of Myocardial Angiotensin Receptors. CURRENT CARDIOVASCULAR IMAGING REPORTS 2013. [DOI: 10.1007/s12410-013-9245-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
10
|
Modeling of the renal kinetics of the AT1 receptor specific PET radioligand [11C]KR31173. BIOMED RESEARCH INTERNATIONAL 2013; 2013:835859. [PMID: 24083243 PMCID: PMC3780470 DOI: 10.1155/2013/835859] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 07/17/2013] [Indexed: 11/18/2022]
Abstract
Purpose. The radioligand [11C]KR31173 has been introduced for PET imaging of the angiotensin II subtype 1 receptor (AT1R). The purpose of the present project was to employ and validate a compartmental model for quantification of the kinetics of this radioligand in a porcine model of renal ischemia followed by reperfusion (IR). Procedures. Ten domestic pigs were included in the study: five controls and five experimental animals with IR of the left kidney. To achieve IR, acute ischemia was created with a balloon inserted into the left renal artery and inflated for 60 minutes. Reperfusion was achieved by deflation and removal of the balloon. Blood chemistries, urine specific gravity and PH values, and circulating hormones of the renin angiotensin system were measured and PET imaging was performed one week after IR. Cortical time-activity curves obtained from a 90 min [11C]KR31173 dynamic PET study were processed with a compartmental model that included two tissue compartments connected in parallel. Radioligand binding quantified by radioligand retention (80 min value to maximum value ratio) was compared to the binding parameters derived from the compartmental model. A binding ratio was calculated as DVR = DVS/DVNS, where DVS and DVNS represented the distribution volumes of specific binding and nonspecific binding. Receptor binding was also determined by autoradiography in vitro. Results. Correlations between rate constants and binding parameters derived by the convolution and deconvolution curve fittings were significant (r > 0.9). Also significant was the correlation between the retention parameter derived from the tissue activity curve (Yret) and the retention parameter derived from the impulse response function (fret). Furthermore, significant correlations were found between these two retention parameters and DVR. Measurements with PET showed no significant changes in the radioligand binding parameters caused by IR, and these in vivo findings were confirmed by autoradiography performed in vitro. Conclusions. Correlations between various binding parameters support the concept of the parallel connectivity compartmental model. If an arterial input function cannot be obtained, simple radioligand retention may be adequate for estimation of in vivo radioligand binding.
Collapse
|
11
|
Analysis of [11C]methyl-candesartan kinetics in the rat kidney for the assessment of angiotensin II type 1 receptor density in vivo with PET. Nucl Med Biol 2013; 40:252-61. [DOI: 10.1016/j.nucmedbio.2012.10.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/30/2012] [Accepted: 10/31/2012] [Indexed: 11/22/2022]
|
12
|
Hermus L, van Dam GM, Zeebregts CJ. Advanced carotid plaque imaging. Eur J Vasc Endovasc Surg 2009; 39:125-33. [PMID: 20031452 DOI: 10.1016/j.ejvs.2009.11.020] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 11/17/2009] [Indexed: 10/20/2022]
Abstract
Treatment of carotid artery stenosis by endarterectomy or stenting can significantly reduce stroke risk. In clinical practice, indication for surgery or stenting is primarily based on the degree of stenosis, but there is growing awareness that pathophysiological features within a vulnerable plaque play a key role in predicting stroke risk. Important molecular processes associated with plaque vulnerability are inflammation, lipid accumulation, proteolysis, apoptosis, angiogenesis and thrombosis. The rapidly emerging field of molecular and functional imaging strategies allows identification of pathophysiological processes in carotid artery stenosis. We aimed to review the literature regarding the current most promising advanced imaging techniques in carotid artery disease. Various advanced imaging methods are available, such as high-resolution magnetic resonance imaging (HR-MRI), single photon emission computed tomography (SPECT), positron emission tomography (PET) and near-infrared fluorescence (NIRF). Radionuclide and fluorescent tracers that identify inflammation, apoptosis and proteolysis, such as FDG, MMP probes and Annexin A5, are promising. A combination of activity of molecular processes and detailed anatomic information can be obtained, providing a powerful tool in the identification of the vulnerable plaque. With these developments, we are entering a new era of imaging techniques in the selection of patients for carotid surgery.
Collapse
Affiliation(s)
- L Hermus
- Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | | |
Collapse
|
13
|
Åberg O, Lindhe Ö, Hall H, Hellman P, Kihlberg T, Långström B. Synthesis and biological evaluation of [carboxyl-11C]eprosartan. J Labelled Comp Radiopharm 2009. [DOI: 10.1002/jlcr.1598] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
14
|
Verjans JWH, Lovhaug D, Narula N, Petrov AD, Indrevoll B, Bjurgert E, Krasieva TB, Petersen LB, Kindberg GM, Solbakken M, Cuthbertson A, Vannan MA, Reutelingsperger CPM, Tromberg BJ, Hofstra L, Narula J. Noninvasive imaging of angiotensin receptors after myocardial infarction. JACC Cardiovasc Imaging 2009; 1:354-62. [PMID: 19356449 DOI: 10.1016/j.jcmg.2007.11.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 11/14/2007] [Accepted: 11/20/2007] [Indexed: 12/16/2022]
Abstract
OBJECTIVES The purpose of this study was to evaluate the feasibility of noninvasive imaging of angiotensin II (AT) receptor upregulation in a mouse model of post-myocardial infarction (MI) heart failure (HF). BACKGROUND Circulating AT levels do not reflect the status of upregulation of renin-angiotensin axis in the myocardium, which plays a central role in ventricular remodeling and evolution of HF after MI. Appropriately labeled AT or AT receptor blocking agents should be able to specifically target AT receptors by molecular imaging techniques. METHODS AT receptor imaging was performed in 29 mice at various time points after permanent coronary artery ligation or in controls using a fluoresceinated angiotensin peptide analog (APA) and radiolabeled losartan. The APA was used in 19 animals for intravital fluorescence microscopy on a beating mouse heart. Tc-99m losartan was used for in vivo radionuclide imaging and quantitative assessment of AT receptor expression in 10 mice. After imaging, hearts were harvested for pathological characterization using confocal and 2-photon microscopy. RESULTS No or little APA uptake was observed in control animals or within infarct regions on days 0 and 1. Distinct uptake occurred in the infarct area at 1 to 12 weeks after MI; the uptake was at maximum at 3 weeks and reduced markedly at 12 weeks after MI. Ultrasonographic examination demonstrated left ventricular remodeling, and pathologic characterization revealed localization of the APA tracer with collagen-producing myofibroblasts. Tc-99m losartan uptake in the infarct region (0.524 +/- 0.212% injected dose/g) increased 2.4-fold as compared to uptake in the control animals (0.215 +/- 0.129%; p < 0.05). CONCLUSIONS The present study demonstrates the feasibility of in vivo molecular imaging of AT receptors in the remodeling myocardium. Noninvasive imaging studies aimed at AT receptor expression could play a role in identification of subjects likely to develop heart failure. In addition, such a strategy could allow for optimization of anti-angiotensin therapy in patients after MI.
Collapse
Affiliation(s)
- Johan W H Verjans
- Department of Cardiology, University of California at Irvine, School of Medicine, 101 The City Drive, Orange, CA 92868-4080, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Shirani J, Dilsizian V. Imaging left ventricular remodeling: targeting the neurohumoral axis. ACTA ACUST UNITED AC 2008; 5 Suppl 2:S57-62. [PMID: 18641608 DOI: 10.1038/ncpcardio1244] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Accepted: 04/11/2008] [Indexed: 01/28/2023]
Abstract
Left ventricular remodeling is a key determinant of the clinical course and outcome of systolic heart failure. The myocardial renin-angiotensin system (RAS) has been closely linked to the major maladaptive cellular and molecular changes that accompany left ventricular remodeling. Direct inhibition of various components of the RAS, such as the angiotensin-converting enzyme, angiotensin II type 1 receptor, and aldosterone, has resulted in favorable clinical responses in heart failure. Many questions, however, remain unanswered regarding the timing of initiation, optimum doses, need for simultaneous use of RAS inhibitors, and proper monitoring of RAS blockade. Additionally, significant variation has been noted in individual responses to RAS blockade as a result of genetic differences. Answering these questions requires direct access to the myocardial component of RAS, which is largely independent of its systemic component. Molecular imaging using radiotracers with high affinities for myocardial angiotensin-converting enzyme and angiotensin II type 1 receptors can provide direct access to tissue RAS and thus provide a better understanding of the pathophysiology of left ventricular remodeling in individual patients. This Article briefly reviews the potential for evaluating the tissue expression of angiotensin in heart failure by targeted RAS imaging.
Collapse
Affiliation(s)
- Jamshid Shirani
- Department of Cardiology, Geisinger Medical Center, 100 North Academy Avenue, Danville, PA 17822-2160, USA.
| | | |
Collapse
|
16
|
Can nuclear medicine shed light on the dark side of angiogenesis in cardiovascular disease? Nucl Med Commun 2008; 29:585-7. [DOI: 10.1097/mnm.0b013e3283000070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
17
|
Zhuo JL. Intrarenal Perfusion and Angiotensin II Levels Regulate In Vivo Angiotensin II Type 1 Receptor Imaging in the Kidney. Hypertension 2008; 51:e52; author reply e53. [DOI: 10.1161/hypertensionaha.108.112276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jia L. Zhuo
- Laboratory of Receptor and Signal Transduction, Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Hospital, Detroit, Mich
| |
Collapse
|
18
|
Szabo Z, Xia J, Mathews WB. Radiopharmaceuticals for renal positron emission tomography imaging. Semin Nucl Med 2008; 38:20-31. [PMID: 18096461 DOI: 10.1053/j.semnuclmed.2007.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radiopharmaceuticals for functional renal imaging, including renal blood flow, renal blood volume, glomerular excretion, and metabolism have been available for some time. This review outlines radiopharmaceuticals for functional renal imaging as well as those that target pertinent molecular constituents of renal injury and repair. The angiotensin and endothelin receptors are particularly appealing molecular targets for renal imaging because of their association with renal physiology and pathology. Other targets such as the vascular endothelial growth factor (VEGF) receptor, integrin, or phosphatidylserine have been investigated at length for cancer imaging, but they are just as important constituents of the renal injury/repair process. Various diseases can involve identical mechanisms, such as angiogenesis and apoptosis, and radiopharmaceuticals developed for these processes in other organs can also be used for renal imaging. The sensitivity and spatial resolution of positron emission tomography makes it an ideal tool for molecular and functional kidney imaging. Radiopharmaceutical development for the kidneys must focus on achieving high target selectivity and binding affinity, stability and slow metabolism in vivo, and minimal nonspecific accumulation and urinary excretion.
Collapse
Affiliation(s)
- Zsolt Szabo
- Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | | | | |
Collapse
|
19
|
Xia J, Seckin E, Xiang Y, Vranesic M, Mathews WB, Hong K, Bluemke DA, Lerman LO, Szabo Z. Positron-Emission Tomography Imaging of the Angiotensin II Subtype 1 Receptor in Swine Renal Artery Stenosis. Hypertension 2008; 51:466-73. [DOI: 10.1161/hypertensionaha.107.102715] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The angiotensin II subtype 1 receptor (AT
1
R) has been linked to the development and progression of renovascular hypertension. In this study we applied a pig model of renovascular hypertension to investigate the AT
1
R in vivo with positron-emission tomography (PET) and in vitro with quantitative autoradiography. AT
1
R PET measurements were performed with the radioligand [
11
C]KR31173 in 11 control pigs and in 13 pigs with hemodynamically significant renal artery stenosis; 4 were treated with lisinopril for 2 weeks before PET imaging. The radioligand impulse response function was calculated by deconvolution analysis of the renal time-activity curves. Radioligand binding was quantified by the 80-minute retention of the impulse response function. Median values and interquartile ranges were used to illustrate group statistics. Radioligand retention was significantly increased (
P
=0.044) in hypoperfused kidneys of untreated (0.225; range: 0.150 to 0.373) and lisinopril-treated (0.237; range:0.224 to 0.272) animals compared with controls (0.142; range:0.096 to 0.156). Increased binding of [
11
C]KR31173 documented by PET in vivo was confirmed by in vitro autoradiography. Both in vivo and in vitro binding measurements showed that the effect of renal artery stenosis on the AT
1
R was not abolished by lisinopril treatment. These studies provide insight into kidney biology as the first in vivo/in vitro experimental evidence about AT
1
R regulation in response to reduced perfusion of the kidney. The findings support the concept of introducing AT
1
R PET as a diagnostic biomarker of renovascular disease.
Collapse
Affiliation(s)
- Jinsong Xia
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Esen Seckin
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Yan Xiang
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Melin Vranesic
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - William B. Mathews
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Kelvin Hong
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - David A. Bluemke
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Lilach O. Lerman
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| | - Zsolt Szabo
- From the Departments of Radiology (J.X., E.S., M.V., W.B.M., K.H., D.A.B., Z.S.) and Physiology (Y.X.), Johns Hopkins Medical Institutions, Baltimore, Md; Department of Medicine (L.O.L.), Mayo Clinic College of Medicine, Rochester, Minn
| |
Collapse
|
20
|
Zober TG, Fabucci ME, Zheng W, Brown PR, Seckin E, Mathews WB, Sandberg K, Szabo Z. Chronic ACE inhibitor treatment increases angiotensin type 1 receptor binding in vivo in the dog kidney. Eur J Nucl Med Mol Imaging 2008; 35:1109-16. [PMID: 18180920 DOI: 10.1007/s00259-007-0667-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Accepted: 11/26/2007] [Indexed: 12/19/2022]
Abstract
PURPOSE PET imaging has been recently introduced for investigating the type 1 angiotensin II receptor (AT(1)R) in vivo. The goal of the present study was to investigate the effects of acute and chronic exposure to angiotensin converting enzyme inhibitors (ACEI) on the AT(1)R in the dog kidney. METHODS Animals were imaged at baseline, after acute intravenous ACEI treatment and after a chronic 2-week exposure to an oral ACEI. Control animals were imaged at identical time points in the absence of ACEI treatment. RESULTS In vivo AT(1)R binding expressed by K (i) was increased in the renal cortex by chronic ACEI treatment (p < 0.05). In vitro measurements of AT(1)R density (B (max)) also revealed significant increases in AT(1)R in isolated glomeruli (p < 0.05). Plasma renin activity was increased, but angiotensin II (Ang II) and the Ang II/Ang I ratio showed a weak correlation with chronic ACEI treatment, consistent with an Ang II escape phenomenon. CONCLUSION This study reveals, for the first time, that chronic ACEI treatment increases AT(1)R binding in vivo in the dog renal cortex.
Collapse
Affiliation(s)
- Tamas G Zober
- Department of Radiology and Surgery, Johns Hopkins University, Baltimore, MD, USA
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Aras O, Messina SA, Shirani J, Eckelman WC, Dilsizian V. The role and regulation of cardiac angiotensin-converting enzyme for noninvasive molecular imaging in heart failure. Curr Cardiol Rep 2007; 9:150-8. [PMID: 17430683 DOI: 10.1007/bf02938342] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Congestive heart failure is a pathologic condition characterized by progressive decrease in left ventricular contractility and consequent decline of cardiac output. There is convincing clinical and experimental evidence that the renin-angiotensin system (RAS) and its primary effector peptide, angiotensin II, are linked to the pathophysiology of interstitial fibrosis, cardiac remodeling, and heart failure. In addition to the traditional endocrine or circulating RAS, an active tissue RAS has been characterized. Tissue angiotensin-converting enzyme and locally synthesized angiotensin II, for example, by chymase, exert local trophic effects that modulate gene expression, which regulates growth and proliferation in both myocytes and nonmyocytes. The existence of the tissue RAS offers an opportunity for targeted imaging, which may be of considerable value for guiding medical therapy.
Collapse
Affiliation(s)
- Omer Aras
- Division of Nuclear Medicine, Department of Diagnostic Radiology, University of Maryland Hospital and School of Medicine, Baltimore, MD 21201-1595, USA
| | | | | | | | | |
Collapse
|
22
|
Zober TG, Mathews WB, Seckin E, Yoo SE, Hilton J, Xia J, Sandberg K, Ravert HT, Dannals RF, Szabo Z. PET Imaging of the AT1 receptor with [11C]KR31173. Nucl Med Biol 2006; 33:5-13. [PMID: 16459253 PMCID: PMC1819586 DOI: 10.1016/j.nucmedbio.2005.08.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 08/22/2005] [Accepted: 08/23/2005] [Indexed: 10/25/2022]
Abstract
AIM The goal of this study was to investigate the binding characteristics of [(11)C]KR31173 and its applicability for PET studies of the AT(1) receptor (AT(1)R). METHODS Ex vivo biodistribution and pharmacology were tested in mice. PET imaging was performed in mice, beagle dogs and a baboon. To assess nonspecific binding, PET imaging was performed both before and after pretreatment with a potent AT(1)R antagonist. In the baboon, PET imaging was also performed with the previously developed radioligand [(11)C]L-159,884 for comparison. RESULTS Ex vivo biodistribution studies in mice showed specific binding rates of 80-90% in the adrenals, kidneys, lungs and heart. Specific binding was confirmed in mice using small animal PET. In dogs, renal cortex tissue concentration at 75-95 min postinjection (pi) was 63 nCi/ml per millicurie at a specific binding rate of 95%. In the baboon renal cortex, tissue activity at 55-75 min pi was 345 nCi/ml per millicurie. In the baboon the specific binding of [(11)C]KR31173 was higher (81%) than the specific binding of [(11)C]L-159,884 (34%). CONCLUSION [(11)C]KR31173 shows accumulation and significant specific binding to the AT(1)R in the kidneys of mice, dogs and baboon. These findings suggest that this radioligand is suited for imaging the renal cortical AT(1)R in multiple species.
Collapse
Affiliation(s)
- Tamas G. Zober
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - William B. Mathews
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Esen Seckin
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Sung E. Yoo
- The Center for Biological Modulators, The Korea Research Institute of Chemical Technology, Daejeon, South Korea
| | - John Hilton
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Jinsong Xia
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Kathryn Sandberg
- Department of Medicine, Georgetown University, Washington, DC U.S.A
| | - Hayden T. Ravert
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Robert F. Dannals
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| | - Zsolt Szabo
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD U.S.A
| |
Collapse
|
23
|
Shirani J, Narula J, Eckelman WC, Dilsizian V. Novel Imaging Strategies for Predicting Remodeling and Evolution of Heart Failure: Targeting the Renin-angiotensin System. Heart Fail Clin 2006; 2:231-47. [PMID: 17386892 DOI: 10.1016/j.hfc.2006.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
24
|
Haufe SE, Riedmüller K, Haberkorn U. Nuclear medicine procedures for the diagnosis of acute and chronic renal failure. Nephron Clin Pract 2006; 103:c77-84. [PMID: 16543760 DOI: 10.1159/000091576] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The focus of this review is on the current role of nuclear imaging studies in the clinical evaluation of patients with acute and chronic renal failure. In this setting nuclear imaging has two roles: diagnostic and prognostic, indicating that these methods are an essential component in the evaluation of renal diseases. The functional assessment of the kidney by nuclear medicine procedures is based on the use of radioisotopes bound to non-metabolized molecules with known pharmacokinetics. Renal scintigraphy is usually applied for the assessment of renal function expressed as glomerular filtration rate, effective renal plasma flow or more generally kidney perfusion. Newer methods rely on positron emission tomography, which allows the generation of images with higher resolution and absolute quantitation of biological processes such as transport activities, enzyme activities or angiotensin receptors.
Collapse
Affiliation(s)
- Sabine E Haufe
- Department of Nuclear Medicine, University of Heidelberg, Heidelberg, Germany
| | | | | |
Collapse
|
25
|
Abstract
Positron emission tomography (PET) is perfectly suited for quantitative imaging of the kidneys, and the recent improvements in detector technology, computer hardware, and image processing software add to its appeal. Multiple positron emitting radioisotopes can be used for renal imaging. Some, including carbon-11, nitrogen-13, and oxygen-15, can be used at institutions with an on-site cyclotron. Other radioisotopes that may be even more useful in a clinical setting are those that either can be obtained from radionuclide generators (rubidium-82, copper-62) or have a sufficiently long half-life for transportation (fluorine-18). The clinical use of functional renal PET studies (blood flow, glomerular filtration rate) has been slow, in part because of the success of concurrent technologies, including single-photon emission computed tomography (SPECT) and planar gamma camera imaging. Renal blood flow studies can be performed with O-15-labeled water, N-13-labeled ammonia, rubidium-82, and copper-labeled PTSM. With these tracers, renal blood flow can be quantified using a modified microsphere kinetic model. Glomerular filtration can be imaged and quantified with gallium-68 EDTA or cobalt-55 EDTA. Measurements of renal blood flow with PET have potential applications in renovascular disease, in transplant rejection or acute tubular necrosis, in drug-induced nephropathies, ureteral obstruction, before and after revascularization, and before and after the placement of ureteral stents. The most important clinical application for imaging glomerular function with PET would be renovascular hypertension. Molecular imaging of the kidneys with PET is rather limited. At present, research is focused on the investigation of metabolism (acetate), membrane transporters (organic cation and anion transporters, pepT1 and pepT2, GLUT, SGLT), enzymes (ACE), and receptors (AT1R). Because many nephrological and urological disorders are initiated at the molecular and organelle levels and may remain localized at their origin for an extended period of time, new disease-specific molecular probes for PET studies of the kidneys need to be developed. Future applications of molecular renal imaging are likely to involve studies of tissue hypoxia and apoptosis in renovascular renal disease, renal cancer, and obstructive nephropathy, monitoring the molecular signatures of atherosclerotic plaques, measuring endothelial dysfunction and response to balloon revascularization and restenosis, molecular assessment of the nephrotoxic effects of cyclosporine, anticancer drugs, and radiation therapy. New radioligands will enhance the staging and follow-up of renal and prostate cancer. Methods will be developed for investigation of the kinetics of drug-delivery systems and delivery and deposition of prodrugs, reporter gene technology, delivery of gene therapy (nuclear and mitochondrial), assessment of the delivery of cellular, viral, and nonviral vectors (liposomes, polycations, fusion proteins, electroporation, hematopoietic stems cells). Of particular importance will be investigations of stem cell kinetics, including local presence, bloodborne migration, activation, seeding, and its role in renal remodeling (psychological, pathological, and therapy induced). Methods also could be established for investigating the role of receptors and oncoproteins in cellular proliferation, apoptosis, tubular atrophy, and interstitial fibrosis; monitoring ras gene targeting in kidney diseases, assessing cell therapy devices (bioartificial filters, renal tubule assist devices, and bioarticial kidneys), and targeting of signal transduction moleculas with growth factors and cytokines. These potential new approaches are, at best, in an experimental stage, and more research will be needed for their implementation.
Collapse
Affiliation(s)
- Zsolt Szabo
- Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | | | | | | |
Collapse
|
26
|
Shirani J, Loredo ML, Eckelman WC, Jagoda EM, Dilsizian V. Imaging the renin-angiotensin-aldosterone system in the heart. Curr Heart Fail Rep 2005; 2:78-86. [PMID: 16036055 DOI: 10.1007/s11897-005-0013-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The influence of the renin-angiotensin system (RAS) is recognized in cardiac and vascular injury. An extrinsic RAS has been known for decades, and an equally important intrinsic RAS has been discovered recently. The latter leads to pathologic tissue alterations in the absence of systemic stimuli and may be the main source of local tissue effects of RAS. A new radiotracer fluorobenzoyl-lisinopril was synthesized by radiolabeling benzoic acid active ester with 18F and reacting that with the epsilon-amino group of lisinopril. The presence of angiotensin-converting enzyme (ACE) activity and angiotensin II receptors was examined in relation to myocardial fibrosis. This tissue-specific radioligand represents the first study of ACE in the human heart. This article presents preliminary data on imaging the RAS in the human cardiac tissue and discusses the potential for clinical application of these imaging techniques to human patients.
Collapse
Affiliation(s)
- Jamshid Shirani
- Geisinger Medical Center, Division of Cardiology, 100 North Academy Avenue, Danville, PA 17822, USA.
| | | | | | | | | |
Collapse
|
27
|
Mathews WB, Yoo SE, Lee SH, Scheffel U, Rauseo PA, Zober TG, Gocco G, Sandberg K, Ravert HT, Dannals RF, Szabo Z. A novel radioligand for imaging the AT1 angiotensin receptor with PET. Nucl Med Biol 2004; 31:571-4. [PMID: 15219274 DOI: 10.1016/j.nucmedbio.2003.10.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2003] [Revised: 10/08/2003] [Accepted: 10/31/2003] [Indexed: 11/22/2022]
Abstract
2-Butyl-5-methoxymethyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-3H-imidazo[4,5-b]pyridine (KR31173) was radiolabeled by coupling a tetrazole-protected hydroxy precursor with [(11)C] methyl iodide and removing the protecting group by acid hydrolysis. In mice, the highest uptake of [(11)C] KR31173 was in the adrenal glands, kidneys, and liver. Tissue to blood ratios were generally greater than 10:1. Uptake of the tracer in the adrenal glands, kidneys, lungs, and heart was blocked with a 1 mg/kg dose of KR31173 or MK-996.
Collapse
Affiliation(s)
- William B Mathews
- Department of Radiology, Room B1151 Nelson Building, Johns Hopkins Medical Institutions, 600 North Wolfe St., Baltimore, MD 21287, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Katugampola S, Davenport A. Emerging roles for orphan G-protein-coupled receptors in the cardiovascular system. Trends Pharmacol Sci 2003; 24:30-5. [PMID: 12498728 DOI: 10.1016/s0165-6147(02)00007-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Despite current drug therapies, including those that target enzymes, channels and known G-protein-coupled receptors (GPCRs), cardiovascular disease remains the major cause of ill health, which suggests that other transmitter systems might be involved in this disease. In humans, approximately 175 genes have been predicted to encode 'orphan' GPCRs, where the endogenous ligand is not yet known. As a result of intensive screening using 'reverse pharmacology', an increasing number of orphan receptors are being paired with their cognate ligands, many of which are peptides. The existence of some of these peptides such as urotensin-II and relaxin had been known for some time but others, including ghrelin and apelin, represent novel sequences. The pharmacological characterization of these emerging peptide-receptor systems is a tantalising area of cardiovascular research, with the prospect of identifying new therapeutic targets.
Collapse
|
29
|
Bonnet F, Candido R, Carey RM, Casley D, Russo LM, Osicka TM, Cooper ME, Cao Z. Renal expression of angiotensin receptors in long-term diabetes and the effects of angiotensin type 1 receptor blockade. J Hypertens 2002; 20:1615-24. [PMID: 12172324 DOI: 10.1097/00004872-200208000-00025] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aims of this study were to assess the renal expression of angiotensin type 1 (AT1) and type 2 (AT2) receptors in diabetic spontaneously hypertensive rats (SHR) and the effect of AT1 receptor blockade on the expression of these receptors. DESIGN Diabetes was induced by injection of streptozotocin in SHRs. Irbesartan, an AT1 receptor antagonist, was given to diabetic SHRs for 32 weeks (15 mg/kg per day, n = 10). Diabetic (n = 10) and non-diabetic SHRs (n = 10) were studied concurrently. A separate group of control and diabetic Wistar-Kyoto (WKY) rats were also evaluated. METHODS Gene and protein expressions of the AT1 and AT2 receptor were assessed by reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry with specific antibodies andin vitro autoradiography with [125I]Sar(1), Ile(8) angiotensin II or [125I]CGP42112B. RESULTS Both AT1 and AT2 receptor mRNA levels in the kidney were reduced in diabetic SHRs compared to non-diabetic SHRs. Immunohistochemistry staining with specific antibodies showed a similar reduction in glomerular and tubulo-interstitial staining for both AT1 and AT2 receptors. Reduced binding for the AT1 and AT2 receptor was found in the kidney of diabetic SHRs. Diabetic SHRs developed albuminuria and had glomerular and tubulo-interstitial injury, which were prevented by treatment with irbesartan. Reduced expression of the AT1 receptor, but not the AT2 receptor, in diabetic SHRs was prevented by treatment with irbesartan. In diabetic WKY rats no such reduction in AT1 expression was observed, although there was a trend for reduced AT2 receptor expression. CONCLUSIONS These findings demonstrated that renal expression of both AT1 and AT2 receptor was reduced in long-term diabetic SHRs and that blockade of the AT1 receptor had disparate effects on expression of angiotensin II receptor subtypes.
Collapse
MESH Headings
- Angiotensin Receptor Antagonists
- Animals
- Biphenyl Compounds/therapeutic use
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetic Nephropathies/genetics
- Diabetic Nephropathies/metabolism
- Diabetic Nephropathies/pathology
- Diabetic Nephropathies/prevention & control
- Gene Expression/drug effects
- Irbesartan
- Kidney/drug effects
- Kidney/metabolism
- Kidney/pathology
- Male
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Inbred SHR
- Rats, Inbred WKY
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/metabolism
- Tetrazoles/therapeutic use
Collapse
Affiliation(s)
- Fabrice Bonnet
- Department of Medicine, University of Melbourne, Austin and Repatriation Medical Centre, Heidelberg West, Victoria 3081, Australia
| | | | | | | | | | | | | | | |
Collapse
|