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Pfeifer A, Mikhael M, Niemann B. Inosine: novel activator of brown adipose tissue and energy homeostasis. Trends Cell Biol 2024; 34:72-82. [PMID: 37188562 DOI: 10.1016/j.tcb.2023.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/23/2023] [Accepted: 04/24/2023] [Indexed: 05/17/2023]
Abstract
Extracellular purinergic molecules act as signaling molecules that bind to cellular receptors and regulate signaling pathways. Growing evidence suggests that purines regulate adipocyte function and whole-body metabolism. Here, we focus on one specific purine: inosine. Brown adipocytes, which are important regulators of whole-body energy expenditure (EE), release inosine when they are stressed or become apoptotic. Unexpectedly, inosine activates EE in neighboring brown adipocytes and enhances differentiation of brown preadipocytes. Increasing extracellular inosine, either directly by increasing inosine intake or indirectly via pharmacological inhibition of cellular inosine transporters, increases whole-body EE and counteracts obesity. Thus, inosine and other closely related purines might be a novel approach to tackle obesity and associated metabolic disorders by enhancing EE.
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Affiliation(s)
- Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany.
| | - Mickel Mikhael
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Birte Niemann
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
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2
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Tsukagoshi-Yamaguchi A, Koshizaka M, Ishibashi R, Ishikawa K, Ishikawa T, Shoji M, Ide S, Ide K, Baba Y, Terayama R, Hattori A, Takemoto M, Ouchi Y, Maezawa Y, Yokote K. Metabolomic analysis of serum samples from a clinical study on ipragliflozin and metformin treatment in Japanese patients with type 2 diabetes: Exploring human metabolites associated with visceral fat reduction. Pharmacotherapy 2023; 43:1317-1326. [PMID: 37772313 DOI: 10.1002/phar.2884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/02/2023] [Accepted: 09/05/2023] [Indexed: 09/30/2023]
Abstract
STUDY OBJECTIVE The effects of the sodium-dependent glucose transporter-2 inhibitor ipragliflozin were compared with metformin in a previous study, which revealed that ipragliflozin reduced visceral fat content by 12%; however, the underlying mechanism was unclear. Therefore, this sub-analysis aimed to compare metabolomic changes associated with ipragliflozin and metformin that may contribute to their biological effects. DESIGN A sub-analysis of a randomized controlled study. SETTING Chiba University Hospital and ten hospitals in Japan. PATIENTS Fifteen patients with type 2 diabetes in the ipragliflozin group and 15 patients with type 2 diabetes in the metformin group with matching characteristics, such as age, sex, baseline A1C, baseline visceral fat area, smoking status, and concomitant medication. INTERVENTIONS Ipragliflozin 50 mg or metformin 1000 mg daily. MEASUREMENTS The clinical data were reanalyzed, and metabolomic analysis of serum samples collected before and 24 weeks after drug administration was performed using capillary electrophoresis time-of-flight mass spectrometry. MAIN RESULTS The reduction in the mean visceral fat area after 24 weeks of treatment was significantly larger (p = 0.002) in the ipragliflozin group (-19.8%) than in the metformin group (-2.5%), as were the subcutaneous fat area and body weight. The A1C and blood glucose levels decreased in both groups. Glutamic pyruvic oxaloacetic transaminase, γ-glutamyl transferase, uric acid, and triglyceride levels decreased in the ipragliflozin group. Low-density lipoprotein cholesterol levels decreased in the metformin group. After ipragliflozin administration, N2-phenylacetylglutamine, inosine, guanosine, and 1-methyladenosine levels increased, whereas galactosamine, glucosamine, 11-aminoundecanoic acid, morpholine, and choline levels decreased. After metformin administration, metformin, hypotaurine, methionine, methyl-2-oxovaleric acid, 3-nitrotyrosine, and cyclohexylamine levels increased, whereas citrulline, octanoic acid, indole-3-acetaldehyde, and hexanoic acid levels decreased. CONCLUSIONS Metabolites that may affect visceral fat reduction were detected in the ipragliflozin group. Studies are required to further elucidate the underlying mechanisms.
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Affiliation(s)
| | - Masaya Koshizaka
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
- Center for Preventive Medical Science, Chiba University, Chiba City, Japan
| | - Ryoichi Ishibashi
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
- Division of Diabetes, Endocrinology, and Metabolism, Kimitsu Chuo Hospital, Kisarazu City, Japan
| | - Ko Ishikawa
- Department of Diabetes and Endocrinology, Chiba Rosai Hospital, Ichihara City, Japan
| | - Takahiro Ishikawa
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of General Medical Science, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Mayumi Shoji
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Shintaro Ide
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Kana Ide
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Yusuke Baba
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Ryo Terayama
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
| | - Akiko Hattori
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Minoru Takemoto
- Division of Diabetes, Department of Medicine, Metabolism and Endocrinology, International University of Health and Welfare, Narita City, Japan
| | - Yasuo Ouchi
- Department of Regenerative Medicine, Chiba University Graduate School of Medicine, Chiba City, Japan
- Altos Labs, California, San Diego, USA
| | - Yoshiro Maezawa
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
| | - Koutaro Yokote
- Department of Diabetes, Metabolism and Endocrinology, Chiba University Hospital, Chiba City, Japan
- Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba City, Japan
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3
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Yisireyili M, Hayashi M, Wu H, Uchida Y, Yamamoto K, Kikuchi R, Shoaib Hamrah M, Nakayama T, Wu Cheng X, Matsushita T, Nakamura S, Niwa T, Murohara T, Takeshita K. Xanthine oxidase inhibition by febuxostat attenuates stress-induced hyperuricemia, glucose dysmetabolism, and prothrombotic state in mice. Sci Rep 2017; 7:1266. [PMID: 28455534 PMCID: PMC5430858 DOI: 10.1038/s41598-017-01366-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/29/2017] [Indexed: 12/12/2022] Open
Abstract
Chronic stress is closely linked to the metabolic syndrome, diabetes, hyperuricemia and thromboembolism, but the mechanisms remain elusive. We reported recently that stress targets visceral adipose tissue (VAT), inducing lipolysis, low-grade inflammation with production of inflammatory adipokines, metabolic derangements such as insulin resistance, and prothrombotic state. In the present study, we hypothesized the involvement of VAT xanthine oxidoreductase (XOR), a source of reactive oxygen species (ROS) and uric acid (UA) in the above processes. Restraint stress in mice resulted in upregulation of XOR and xanthine oxidase activity, accumulation of ROS in VAT as well as liver and intestine, increase in serum UA levels, upregulation of NADPH oxidase subunits and downregulation of antioxidant enzymes. Immunohistochemistry and RT-PCR analysis also showed that restraint stress induced VAT monocyte accumulation and proinflammatory adipokine production, resulting in reduced insulin sensitivity and induction of plasminogen activator inhibitor-1 and tissue factor in VAT. Treatment with febuxostat, a potent XO inhibitor, suppressed stress-induced ROS production and VAT inflammation, resulting in improvement of serum UA levels, insulin sensitivity, and prothrombotic tendency. Our results suggest that stress perturbs glucose and UA metabolism, and promotes prothrombotic status, and that XO inhibition by febuxostat might be a potential therapy for stress-related disorders.
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Affiliation(s)
- Maimaiti Yisireyili
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Motoharu Hayashi
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hongxian Wu
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Department of Cardiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yasuhiro Uchida
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Koji Yamamoto
- Department of Blood Transfusion, Nagoya University Hospital, Nagoya, Japan
| | - Ryosuke Kikuchi
- Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan
| | | | - Takayuki Nakayama
- Department of Blood Transfusion, Aichi Medical University Hospital, Nagakute, Japan
| | - Xian Wu Cheng
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tadashi Matsushita
- Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan.,Department of Blood Transfusion, Nagoya University Hospital, Nagoya, Japan
| | - Shigeo Nakamura
- Department of Pathology, Nagoya University Hospital, Nagoya, Japan
| | - Toshimitsu Niwa
- Faculty of Health and Nutrition, Shubun University, Ichinomiya, Aichi, Japan
| | - Toyoaki Murohara
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kyosuke Takeshita
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan. .,Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan.
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Belleville-Rolland T, Sassi Y, Decouture B, Dreano E, Hulot JS, Gaussem P, Bachelot-Loza C. MRP4 (ABCC4) as a potential pharmacologic target for cardiovascular disease. Pharmacol Res 2016; 107:381-389. [PMID: 27063943 DOI: 10.1016/j.phrs.2016.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/02/2016] [Indexed: 01/13/2023]
Abstract
This review focuses on multidrug resistance protein 4 (MRP4 or ABCC4) that has recently been shown to play a role in cAMP homeostasis, a key-pathway in vascular biology and in platelet functions. In vascular system, recent data provide evidence that inhibition of MRP4 prevents human coronary artery smooth muscle cell proliferation in vitro and in vivo, as well as human pulmonary artery smooth muscle cell proliferation in vitro and pulmonary hypertension in mice in vivo. In the heart, MRP4 silencing in adult rat ventricular myocytes results in an increase in intracellular cAMP levels leading to enhanced cardiomyocyte contractility. However, a prolonged inhibition of MRP4 can promote cardiac hypertrophy. In addition, secreted cAMP, through its metabolite adenosine, prevents adrenergically induced cardiac hypertrophy and fibrosis. Finally, MRP4 inhibition in platelets induces a moderate thrombopathy. The localization of MRP4 underlines the emerging concept of cAMP compartmentalization in platelets, which is a major regulatory mechanism in other cells. cAMP storage in platelet dense granules might limit the cAMP cytosolic concentration upon adenylate cyclase activation, a necessary step to induce platelet activation. In this review, we discuss the therapeutic potential of direct pharmacological inhibition of MRP4 in atherothrombotic disease, via its vasodilating and antiplatelet effects.
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Affiliation(s)
- Tiphaine Belleville-Rolland
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; AP-HP, Hôpital Européen Georges Pompidou, Service dhématologie biologique, Paris, France
| | - Yassine Sassi
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Benoit Decouture
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Elise Dreano
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jean-Sébastien Hulot
- AP-HP, Institute of Cardiometabolism and Nutrition (ICAN), Pitié-Salpêtrière Hospital, F-75013 Paris, France; Sorbonne Universités, UPMC Univ. Paris 06, France
| | - Pascale Gaussem
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; AP-HP, Hôpital Européen Georges Pompidou, Service dhématologie biologique, Paris, France
| | - Christilla Bachelot-Loza
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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5
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Tsushima Y, Nishizawa H, Tochino Y, Nakatsuji H, Sekimoto R, Nagao H, Shirakura T, Kato K, Imaizumi K, Takahashi H, Tamura M, Maeda N, Funahashi T, Shimomura I. Uric acid secretion from adipose tissue and its increase in obesity. J Biol Chem 2013; 288:27138-27149. [PMID: 23913681 DOI: 10.1074/jbc.m113.485094] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Obesity is often accompanied by hyperuricemia. However, purine metabolism in various tissues, especially regarding uric acid production, has not been fully elucidated. Here we report, using mouse models, that adipose tissue could produce and secrete uric acid through xanthine oxidoreductase (XOR) and that the production was enhanced in obesity. Plasma uric acid was elevated in obese mice and attenuated by administration of the XOR inhibitor febuxostat. Adipose tissue was one of major organs that had abundant expression and activities of XOR, and adipose tissues in obese mice had higher XOR activities than those in control mice. 3T3-L1 and mouse primary mature adipocytes produced and secreted uric acid into culture medium. The secretion was inhibited by febuxostat in a dose-dependent manner or by gene knockdown of XOR. Surgical ischemia in adipose tissue increased local uric acid production and secretion via XOR, with a subsequent increase in circulating uric acid levels. Uric acid secretion from whole adipose tissue was increased in obese mice, and uric acid secretion from 3T3-L1 adipocytes was increased under hypoxia. Our results suggest that purine catabolism in adipose tissue could be enhanced in obesity.
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Affiliation(s)
- Yu Tsushima
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan; Teijin Institute for Biomedical Research, Teijin Pharma Limited, Hino, Tokyo 191-8512, Japan
| | - Hitoshi Nishizawa
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
| | - Yoshihiro Tochino
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hideaki Nakatsuji
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ryohei Sekimoto
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hirofumi Nagao
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Takashi Shirakura
- Teijin Institute for Biomedical Research, Teijin Pharma Limited, Hino, Tokyo 191-8512, Japan
| | - Kenta Kato
- Teijin Institute for Biomedical Research, Teijin Pharma Limited, Hino, Tokyo 191-8512, Japan
| | | | - Hiroyuki Takahashi
- Teijin Institute for Biomedical Research, Teijin Pharma Limited, Hino, Tokyo 191-8512, Japan
| | - Mizuho Tamura
- Teijin Institute for Biomedical Research, Teijin Pharma Limited, Hino, Tokyo 191-8512, Japan
| | - Norikazu Maeda
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Tohru Funahashi
- Department of Metabolism and Atherosclerosis, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Iichiro Shimomura
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
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6
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Asterholm IW, Scherer PE. Enhanced metabolic flexibility associated with elevated adiponectin levels. THE AMERICAN JOURNAL OF PATHOLOGY 2010. [PMID: 20093494 DOI: 10.2353/ajpath.2010.090647s0002-9440(10)60448-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Metabolically healthy individuals effectively adapt to changes in nutritional state. Here, we focus on the effects of the adipocyte-derived secretory molecule adiponectin on adipose tissue in mouse models with genetically altered adiponectin levels. We found that higher adiponectin levels increased sensitivity to the lipolytic effects of adrenergic receptor agonists. In parallel, adiponectin-overexpressing mice also display enhanced clearance of circulating fatty acids and increased expansion of subcutaneous adipose tissue with chronic high fat diet (HFD) feeding. These adaptive changes to the HFD were associated with increased mitochondrial density in adipocytes, smaller adipocyte size, and a general transcriptional up-regulation of factors involved in lipid storage through efficient esterification of free fatty acids. The physiological response to adiponectin overexpression resembles in many ways the effects of chronic exposure to beta3-adrenergic agonist treatment, which also results in improvements in insulin sensitivity. In addition, using a novel computed tomography-based method for measurements of hepatic lipids, we resolved the temporal events taking place in the liver in response to acute HFD exposure in both wild-type and adiponectin-overexpressing mice. Increased levels of adiponectin potently protect against HFD-induced hepatic lipid accumulation and preserve insulin sensitivity. Given these profound effects of adiponectin, we propose that adiponectin is a factor that increases the metabolic flexibility of adipose tissue, enhancing its ability to maintain proper function under metabolically challenging conditions.
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Affiliation(s)
- Ingrid Wernstedt Asterholm
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8549, USA
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7
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Asterholm IW, Scherer PE. Enhanced metabolic flexibility associated with elevated adiponectin levels. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:1364-76. [PMID: 20093494 DOI: 10.2353/ajpath.2010.090647] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Metabolically healthy individuals effectively adapt to changes in nutritional state. Here, we focus on the effects of the adipocyte-derived secretory molecule adiponectin on adipose tissue in mouse models with genetically altered adiponectin levels. We found that higher adiponectin levels increased sensitivity to the lipolytic effects of adrenergic receptor agonists. In parallel, adiponectin-overexpressing mice also display enhanced clearance of circulating fatty acids and increased expansion of subcutaneous adipose tissue with chronic high fat diet (HFD) feeding. These adaptive changes to the HFD were associated with increased mitochondrial density in adipocytes, smaller adipocyte size, and a general transcriptional up-regulation of factors involved in lipid storage through efficient esterification of free fatty acids. The physiological response to adiponectin overexpression resembles in many ways the effects of chronic exposure to beta3-adrenergic agonist treatment, which also results in improvements in insulin sensitivity. In addition, using a novel computed tomography-based method for measurements of hepatic lipids, we resolved the temporal events taking place in the liver in response to acute HFD exposure in both wild-type and adiponectin-overexpressing mice. Increased levels of adiponectin potently protect against HFD-induced hepatic lipid accumulation and preserve insulin sensitivity. Given these profound effects of adiponectin, we propose that adiponectin is a factor that increases the metabolic flexibility of adipose tissue, enhancing its ability to maintain proper function under metabolically challenging conditions.
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Affiliation(s)
- Ingrid Wernstedt Asterholm
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8549, USA
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8
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Ren J, Mi Z, Stewart NA, Jackson EK. Identification and quantification of 2',3'-cAMP release by the kidney. J Pharmacol Exp Ther 2009; 328:855-65. [PMID: 19033554 PMCID: PMC2646794 DOI: 10.1124/jpet.108.146712] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 11/24/2008] [Indexed: 11/22/2022] Open
Abstract
We recently developed a sensitive assay for 3',5'-cAMP using high-performance liquid chromatography-tandem mass spectrometry. Using this assay, we investigated the release of 3',5'-cAMP from isolated, perfused rat kidneys. To our surprise, we observed a dominant chromatographic peak that was because of an endogenous substance that had the same parent ion as 3',5'-cAMP and that fragmented to the same daughter ion (adenine) as 3',5'-cAMP. However, the retention time of this unknown was approximately 2.9 min, compared with 6.3 min for authentic 3',5'-cAMP. We hypothesized that the unknown substance was an isomer of 3',5'-cAMP. The unknown substance had the same retention time and mass spectral properties as authentic 2',3'-cAMP. Renal venous secretion of 2',3'-cAMP was greater in kidneys from 20-week-old genetically hypertensive rats compared with age-matched normotensive rats (12.49 +/- 2.14 versus 5.32 +/- 1.97 ng/min/g kidney weight, respectively; n = 18). Isoproterenol (1 microM; beta-adrenoceptor agonist) increased renal venous 3',5'-cAMP secretion (approximately 690% of control) but had no effect on 2',3'-cAMP production. In contrast, rapamycin (0.2 microM; activator of mRNA turnover) and iodoacetate + 2,4-dinitrophenol (50 microM; metabolic inhibitors) increased the renal venous secretion of 2',3'-cAMP (approximately 1000 and 4100% of control, respectively) while simultaneously decreasing the renal venous secretion of 3',5'-cAMP. In conclusion, 2',3'-cAMP is a naturally occurring isomer of 3',5'-cAMP that is: 1) not made by adenylyl cyclase; 2) released from kidneys into the extracellular compartment; 3) released more by kidneys from rats with long-standing hypertension; 4) derived from mRNA turnover; and 5) increased by energy depletion.
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Affiliation(s)
- Jin Ren
- Department of Medicine, Center for Clinical Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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9
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Gauthier MS, Miyoshi H, Souza SC, Cacicedo JM, Saha AK, Greenberg AS, Ruderman NB. AMP-activated protein kinase is activated as a consequence of lipolysis in the adipocyte: potential mechanism and physiological relevance. J Biol Chem 2008; 283:16514-24. [PMID: 18390901 DOI: 10.1074/jbc.m708177200] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is activated in adipocytes during exercise and other states in which lipolysis is stimulated. However, the mechanism(s) responsible for this effect and its physiological relevance are unclear. To examine these questions, 3T3-L1 adipocytes were treated with cAMP-inducing agents (isoproterenol, forskolin, and isobutylmethylxanthine), which stimulate lipolysis and activate AMPK. When lipolysis was partially inhibited with the general lipase inhibitor orlistat, AMPK activation by these agents was also partially reduced, but the increases in cAMP levels and cAMP-dependent protein kinase (PKA) activity were unaffected. Likewise, small hairpin RNA-mediated silencing of adipose tissue triglyceride lipase inhibited both forskolin-stimulated lipolysis and AMPK activation but not that of PKA. Forskolin treatment increased the AMP:ATP ratio, and this too was reduced by orlistat. When acyl-CoA synthetase, which catalyzes the conversion of fatty acids to fatty acyl-CoA, was inhibited with triacsin C, the increases in both AMPK activity and AMP:ATP ratio were blunted. Isoproterenol-stimulated lipolysis was accompanied by an increase in oxidative stress, an effect that was quintupled in cells incubated with the AMPK inhibitor compound C. The isoproterenol-induced increase in the AMP:ATP ratio was also much greater in these cells. In conclusion, the results indicate that activation of AMPK in adipocytes by cAMP-inducing agents is a consequence of lipolysis and not of PKA activation. They suggest that AMPK activation in this setting is caused by an increase in the AMP:ATP ratio that appears to be due, at least in part, to the acylation of fatty acids. Finally, this AMPK activation appears to restrain the energy depletion and oxidative stress caused by lipolysis.
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Affiliation(s)
- Marie-Soleil Gauthier
- Diabetes and Metabolism Unit, Department of Medicine Section of Endocrinology, Boston University Medical Center, Boston, Massachusetts 02118, USA.
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Koh HJ, Hirshman M, He H, Li Y, Manabe Y, Balschi J, Goodyear L. Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes. Biochem J 2007; 403:473-81. [PMID: 17253964 PMCID: PMC1876380 DOI: 10.1042/bj20061479] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Exercise increases AMPK (AMP-activated protein kinase) activity in human and rat adipocytes, but the underlying molecular mechanisms and functional consequences of this activation are not known. Since adrenaline (epinephrine) concentrations increase with exercise, in the present study we hypothesized that adrenaline activates AMPK in adipocytes. We show that a single bout of exercise increases AMPKalpha1 and alpha2 activities and ACC (acetyl-CoA carboxylase) Ser79 phosphorylation in rat adipocytes. Similarly to exercise, adrenaline treatment in vivo increased AMPK activities and ACC phosphorylation. Pre-treatment of rats with the beta-blocker propranolol fully blocked exercise-induced AMPK activation. Increased AMPK activity with exercise and adrenaline treatment in vivo was accompanied by an increased AMP/ATP ratio. Adrenaline incubation of isolated adipocytes also increased the AMP/ATP ratio and AMPK activities, an effect blocked by propranolol. Adrenaline incubation increased lipolysis in isolated adipocytes, and Compound C, an AMPK inhibitor, attenuated this effect. Finally, a potential role for AMPK in the decreased adiposity associated with chronic exercise was suggested by marked increases in AMPKalpha1 and alpha2 activities in adipocytes from rats trained for 6 weeks. In conclusion, both acute and chronic exercise are significant regulators of AMPK activity in rat adipocytes. Our findings suggest that adrenaline plays a critical role in exercise-stimulated AMPKalpha1 and alpha2 activities in adipocytes, and that AMPK can function in the regulation of lipolysis.
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Affiliation(s)
- Ho-Jin Koh
- *Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, U.S.A
| | - Michael F. Hirshman
- *Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, U.S.A
| | - Huamei He
- †NMR Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, U.S.A
| | - Yangfeng Li
- *Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, U.S.A
| | - Yasuko Manabe
- *Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, U.S.A
| | - James A. Balschi
- †NMR Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, U.S.A
| | - Laurie J. Goodyear
- *Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, U.S.A
- To whom correspondence should be addressed (email )
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Jackson EK, Mi Z, Dubey RK. The extracellular cAMP-adenosine pathway significantly contributes to the in vivo production of adenosine. J Pharmacol Exp Ther 2006; 320:117-23. [PMID: 17028245 DOI: 10.1124/jpet.106.112748] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The extracellular cAMP-adenosine pathway is the cellular egress of cAMP followed by extracellular conversion of cAMP to adenosine by the sequential actions of ecto-phosphodiesterase and ecto-5'-nucleotidase. Although detailed studies in isolated organs, tissues, and cells provide evidence for an extracellular cAMP-adenosine pathway, whether this mechanism contributes significantly to adenosine production in vivo is unclear. 1,3-Dipropyl-8-p-sulfophenylxanthine is restricted to the extracellular compartment due to a negative charge at physiological pH and, at high concentrations (> or =0.1 mM), blocks ecto-phosphodiesterase. Here, we show that administration of 1,3-dipropyl-8-p-sulfophenylxanthine at a dose that provided concentrations in plasma and urine of approximately 0.3 and 6 mM, respectively, inhibited urinary adenosine excretion. In Sprague-Dawley rats i.v., 1,3-dipropyl-8-p-sulfophenylxanthine (10 mg + 0.15 mg/min) significantly decreased by 48 and 39% the urinary excretion of adenosine (from 3.57 +/- 0.38 to 1.87 +/- 0.14 nmol/30 min; p = 0.0003) and the ratio of urinary adenosine to cAMP (from 0.93 +/- 0.08 to 0.57 +/- 0.06; p = 0.0044), respectively, without altering blood pressure, renal blood flow, or glomerular filtration rate. Although 1,3-dipropyl-8-p-sulfophenylxanthine transiently increased urine volume and sodium excretion, these effects subsided, yet adenosine excretion remained reduced. Thus, changes in systemic and renal hemodynamics and excretory function could not account for the effects of 1,3-dipropyl-8-p-sulfophenylxanthine on adenosine excretion. Additional experiments showed that 1,3-dipropyl-8-p-sulfophenylxanthine, as in Sprague-Dawley rats, significantly attenuated adenosine excretion and the ratio of urinary adenosine to cAMP in both Wistar-Kyoto rats and spontaneously hypertensive rats. We conclude that the extracellular cAMP-adenosine pathway significantly contributes to the in vivo production of adenosine.
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Affiliation(s)
- Edwin K Jackson
- Center for Clinical Pharmacology, Department of Pharmacology, University of Pittsburgh School of Medicine, 100 Technology Drive, Suite 450, Pittsburgh, PA 15219-3130, USA.
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Abstract
Many cell types in the kidney express adenosine receptors, and adenosine has multiple effects on renal function. Although adenosine is produced within the kidney by several biochemical reactions, recent studies support a novel mechanism for renal adenosine production, the extracellular cAMP-adenosine pathway. This extracellular cAMP-adenosine pathway is initiated by efflux of cAMP from cells following activation of adenylyl cyclase. Extracellular cAMP is then converted to adenosine by the serial actions of ecto-phosphodiesterase and ecto-5'-nucleotidase. When extracellular cAMP is converted to adenosine near the biophase of cAMP production and efflux, this local extracellular cAMP-adenosine pathway permits tight coupling of the site of adenosine production to the site of adenosine receptors. cAMP in renal compartments may also be formed by tissues/organs remote from the kidney. For example, stimulation of hepatic adenylyl cyclase by the pancreatic hormone glucagon increases circulating cAMP, which is filtered at the glomerulus and concentrated in the tubular lumen as water is extracted from the ultrafiltrate. Conversion of hepatic-derived cAMP to adenosine in the kidney completes a pancreatohepatorenal cAMP-adenosine pathway that may serve as an endocrine link between the pancreas, liver, and kidney.
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Affiliation(s)
- Edwin K Jackson
- Center for Clinical Pharmacology, Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA. edj+@pitt.edu
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Liang HX, Belardinelli L, Ozeck MJ, Shryock JC. Tonic activity of the rat adipocyte A1-adenosine receptor. Br J Pharmacol 2002; 135:1457-66. [PMID: 11906959 PMCID: PMC1573251 DOI: 10.1038/sj.bjp.0704586] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Adipocyte A(1)-adenosine receptors (A(1) AdoR) tonically inhibit adenylyl cyclase and lipolysis. Three potential explanations for tonic activity of A(1)AdoR of rat epididymal adipocytes were investigated: high affinity of adenosine for the receptor, efficient coupling of receptor activation to response, and spontaneous activity of the receptor in the absence of agonist. 2. The affinity of adenosine for the adipocyte A(1)AdoR was determined as 4.6 microM by analysis of effects of an irreversible receptor antagonist on agonist concentration-response relationships. In contrast, the potency of adenosine to decrease cyclic AMP in isolated adipocytes was 1.4 nM. 3. Occupancy by agonist of the A(1)AdoR was efficiently coupled to functional response (decrease of adipocyte cyclic AMP content). Activation by adenosine of less than 1% of A(1)AdoRs caused a near-maximal decrease of cyclic AMP in adipocytes. Thus the receptor reserve for adenosine to decrease cyclic AMP content of adipocytes was greater than 99%. 4. Affinities and receptor reserves for other A(1)AdoR agonists were determined. Agonists appeared to differ more in their affinity for the receptor than in their intrinsic efficacy to activate it. 5. A(1)AdoRs were inactive in the absence of agonist. 6. It is concluded that adipocyte A(1)AdoR are tonically activated by endogenous adenosine at nanomolar concentrations. The expression of a high density of A(1)AdoR that are efficiently coupled to a functional response enables the adipocyte to respond with high sensitivity to the low-affinity agonist, adenosine. Adipocytes may be a model for cells whose functions are tonically modulated by adenosine present in the interstitium of well-oxygenated tissues.
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Affiliation(s)
- Hui-Xiu Liang
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida, Gainesville, Florida, FL 32610, U.S.A
| | | | - Mark J Ozeck
- CV Therapeutics, Palo Alto, California, CA 94304, U.S.A
| | - John C Shryock
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida, Gainesville, Florida, FL 32610, U.S.A
- Author for correspondence:
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14
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Jackson EK, Dubey RK. Role of the extracellular cAMP-adenosine pathway in renal physiology. Am J Physiol Renal Physiol 2001; 281:F597-612. [PMID: 11553506 DOI: 10.1152/ajprenal.2001.281.4.f597] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adenosine exerts physiologically significant receptor-mediated effects on renal function. For example, adenosine participates in the regulation of preglomerular and postglomerular vascular resistances, glomerular filtration rate, renin release, epithelial transport, intrarenal inflammation, and growth of mesangial and vascular smooth muscle cells. It is important, therefore, to understand the mechanisms that generate extracellular adenosine within the kidney. In addition to three "classic" pathways of adenosine biosynthesis, contemporary studies are revealing a novel mechanism for renal adenosine production termed the "extracellular cAMP-adenosine pathway." The extracellular cAMP-adenosine pathway is defined as the egress of cAMP from cells during activation of adenylyl cyclase, followed by the extracellular conversion of cAMP to adenosine by the serial actions of ecto-phosphodiesterase and ecto-5'-nucleotidase. This mechanism of extracellular adenosine production may provide hormonal control of adenosine levels in the cell-surface biophase in which adenosine receptors reside. Tight coupling of the site of adenosine production to the site of adenosine receptors would permit a low-capacity mechanism of adenosine biosynthesis to have a large impact on adenosine receptor activation. The purposes of this review are to summarize the physiological roles of adenosine in the kidney; to describe the classic pathways of renal adenosine biosynthesis; to review the evidence for the existence of the extracellular cAMP-adenosine pathway; and to describe possible physiological roles of the extracellular cAMP-adenosine pathway, with particular emphasis on the kidney.
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Affiliation(s)
- E K Jackson
- Department of Pharmacology, University of Pittsburgh School of Medicine, 3550 Terrace St., Pittsburgh, PA 15261, USA. edj+@pitt.edu
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Labelle M, Boulanger Y, Fournier A, St Pierre S, Savard R. Tissue-specific regulation of fat cell lipolysis by NPY in 6-OHDA-treated rats. Peptides 1997; 18:801-8. [PMID: 9285928 DOI: 10.1016/s0196-9781(97)00028-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of neuropeptide Y (NPY), peptide YY (PYY), [Leu31, Pro34]NPY, and NPY (13-36) on adipocyte lipolysis have been studied in subcutaneous (inguinal) and visceral (parametrial) rat adipose tissues. A 48-h fasting period and chemical sympathectomy were used to evaluate the regulation of Y1 and Y2 pathways in rat adipocytes. NPY, PYY, and [Leu31, Pro34]NPY significantly inhibited fat cell lipolysis by about 25% in both tissues (p < or = 0.05). This inhibition was achieved mainly through the Y1 pathway. No significant response to NPY (13-36) was observed, suggesting a lack of involvement of the Y2 pathway in the antilipolytic effect of NPY and PYY. The 48-h fasting period led to the loss of the Y1 inhibitory effect previously observed in control rats. On the other hand, the chemical sympathectomy induced a 35% increase of fat cell lipolysis (p < or = 0.05). The latter involved the Y2 pathway as stimulated by NPY (13-36), and was observed in the parametrial tissue exclusively. These results suggest that: a) rat Y receptors reported to exhibit Gi responses can also express Gs-like responses, and b) visceral and subcutaneous adipose tissues exhibit specific regulation of fat cell lipolysis.
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Affiliation(s)
- M Labelle
- INRS-Santé, Université du Québec à Montréal, Canada
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Jellinek M, Chandel B, Abdulla R, Shapiro MJ, Baue AE. The effect of shock on blood oxidation-reduction potential. EXPERIENTIA 1992; 48:980-5. [PMID: 1426149 DOI: 10.1007/bf01919146] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Oxidation-reduction (redox) potential measurements were made in the blood of rabbits subjected to hemorrhagic shock followed by treatment with a mild oxidizing agent (albumin). Control redox potential reading corrected for pH was -8.8 +/- 1.3 millivolts (mV) in arterial blood (A) and -18.0 +/- 2.0 mV in venous blood (V). This A-V difference indicated that hydrogen equivalents coming from muscle and other tissues were partially consumed in the lungs. A 20-mV drop on the V and a 13 mV on the A side was seen after shock. This did not fully return to control 2 h after return of the shed blood. Infusion of 2 g of albumin/kg/h raised the V redox potential to control, but it returned to untreated levels when the albumin was discontinued. The reductive load imposed on the animal by shock appeared to be large and not readily reversed by reperfusion or by the quantity of albumin given. Thus, it may be concluded that cellular respiration had not been adequately restored. This reductive load may impede recovery by suppression of cellular respiration and other cell and organ functions.
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Affiliation(s)
- M Jellinek
- Department of Surgery, St. Louis University School of Medicine, Missouri 63104
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Friedlander G, Couette S, Coureau C, Amiel C. Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication. J Clin Invest 1992; 90:848-58. [PMID: 1325999 PMCID: PMC329939 DOI: 10.1172/jci115960] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The mechanism of phosphaturia induced by cAMP infusion and the physiological role of extracellular cAMP in modulation of renal phosphate transport were examined. In cultured opossum kidney cells, extracellular cAMP (10-1,000 microM) inhibited Na-dependent phosphate uptake in a time- and concentration-dependent manner. The effect of cAMP was reproduced by ATP, AMP, and adenosine, and was blunted by phosphodiesterase inhibitors or by dipyridamole which inhibits adenosine uptake. [3H]cAMP was degraded extracellularly into AMP and adenosine, and radioactivity accumulated in the cells as labeled adenosine and, subsequently, as adenine nucleotides including cAMP. Radioactivity accumulation was decreased by dipyridamole and by inhibitors of phosphodiesterases and ecto-5'-nucleotidase, assessing the existence of stepwise hydrolysis of extracellular cAMP and intracellular processing of taken up adenosine. In vivo, dipyridamole abolished the phosphaturia induced by exogenous cAMP infusion in acutely parathyroidectomized (APTX) rats, decreased phosphate excretion in intact rats, and blunted phosphaturia induced by PTH infusion in APTX rats. These results indicate that luminal degradation of cAMP into adenosine, followed by cellular uptake of the nucleoside by tubular cells, is a key event which accounts for the phosphaturic effect of exogenous cAMP and for the part of the phosphaturic effect of PTH which is mediated by cAMP added to the tubular lumen under the influence of the hormone.
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Affiliation(s)
- G Friedlander
- Department of Physiology and Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 251, Faculté de Médecine Xavier-Bichat, Université Paris 7, France
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Böttcher H, Engel S, Fürst P. Thermogenesis and metabolism of human white adipocytes in gel culture. Clin Nutr 1992; 11:53-5. [PMID: 16839971 DOI: 10.1016/0261-5614(92)90065-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- H Böttcher
- Institute for Biological Chemistry and Nutrition, University of Hohenheim, Garbenstrasse 30, D-7000 Stuttgart, 70 FRG
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