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Lei JY, Wang PP, Wang HL, Wang Y, Sun L, Hu B, Wang SF, Zhang DM, Chen GM, Liang CM, Tao FB, Yang LS, Wu QS. The associations of non-essential metal mixture with fasting plasma glucose among Chinese older adults without diabetes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:100613-100625. [PMID: 37639099 DOI: 10.1007/s11356-023-29503-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/22/2023] [Indexed: 08/29/2023]
Abstract
The evidence about the effect of non-essential metal mixture on fasting plasma glucose (FPG) levels among older adults without diabetes is limited. This study aims to estimate the individual and joint relationship between five non-essential metals and FPG levels in Chinese older adults without diabetes. This study included 2362 older adults without diabetes. Urinary concentrations of five non-essential metals, i.e., cesium (Cs), aluminum (Al), thallium (Tl), cadmium (Cd), and arsenic (As), were detected by inductively coupled plasma mass spectrometry (ICP-MS). The associations of single metals and the metal mixture with FPG levels were assessed using linear regression and Bayesian kernel machine regression (BKMR) models, respectively. Adjusted single-metal linear regression models showed positive associations of urinary Al (β = 0.016, 95%CI: 0.001-0.030) and Cs (β = 0.018, 95%CI: 0.006-0.031) with FPG levels. When comparing the 2th, 3th, and 4th quartiles of urine Cs to its 1th quartile, the significant associations between Cs and FPG levels were found and presented as an "inverted U" trend (βQ2 vs. Q1: 0.034; βQ3 vs. Q1:0.054; βQ4 vs. Q1: 0.040; all P<0.05). BKMR analyses showed urinary level of Cs exhibited an "inverted U" shape association with FPG levels. Moreover, the FPG levels increased linearly with the raised levels of the non-essential metal mixture, and the posterior inclusion probability (PIP) of Cs was the highest (0.92). Potential positive interaction of As and Cs on FPG levels was found in BKMR model. Stratified analysis displayed significant interactions of hyperlipidemia and urine Cs or Tl on FPG levels. An inverse U-shaped association between Cs and FPG was found, individually and as mixture. The FPG levels increased with the raised levels of the non-essential metal mixture, and Cs was the most contributor to FPG levels. Further research is required to confirm the correlation between non-essential metals and FPG levels and to clarify the underlying mechanisms.
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Affiliation(s)
- Jing-Yuan Lei
- School of Public Health, Department of Hygiene Inspection and Quarantine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Pan-Pan Wang
- School of Public Health, Department of Hygiene Inspection and Quarantine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Hong-Li Wang
- School of Public Health, Department of Epidemiology and Health Statistics, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Yuan Wang
- School of Public Health, Department of Epidemiology and Health Statistics, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Liang Sun
- Fuyang Center for Diseases Prevention and Control, Fuyang, 236069, Anhui, China
| | - Bing Hu
- Fuyang Center for Diseases Prevention and Control, Fuyang, 236069, Anhui, China
| | - Su-Fang Wang
- School of Public Health, Department of Nutrition and Food Hygiene, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Dong-Mei Zhang
- School of Health Services Management, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Gui-Mei Chen
- School of Health Services Management, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Chun-Mei Liang
- School of Public Health, Department of Hygiene Inspection and Quarantine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Fang-Biao Tao
- MOE Key Laboratory of Population Health Across Life Cycle (Anhui Medical University), No. 81 Meishan Road, Hefei, 230032, Anhui, China
| | - Lin-Sheng Yang
- School of Public Health, Department of Epidemiology and Health Statistics, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Qing-Si Wu
- Department of Blood Transfusion, the Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, Anhui, China.
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Belz M, Willenborg M, Görgler N, Hamada A, Schumacher K, Rustenbeck I. Insulinotropic effect of high potassium concentration beyond plasma membrane depolarization. Am J Physiol Endocrinol Metab 2014; 306:E697-706. [PMID: 24452455 DOI: 10.1152/ajpendo.00362.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The question whether K⁺ depolarization is an appropriate experimental substitute for the physiological nutrient-induced depolarization of the β-cell plasma membrane was investigated using primary mouse β-cells and islets. At basal glucose 40 mM K⁺ induced a massive monophasic response, whereas 15 mM K⁺ had only a minimal insulinotropic effect, even though the increase in the cytosolic Ca²⁺ concentration ([Ca²⁺]i) was not inferior to that by 20 mM glucose. In voltage-clamp experiments, Ca²⁺ influx appeared as nifedipine-inhibitable inward action currents in the presence of sulfonylurea plus TEA to block compensatory outward K⁺ currents. Under these conditions, 15 mM K⁺ induced prolonged action currents and 40 mM K⁺ transformed the action current pattern into a continuous inward current. Correspondingly, 15 mM K⁺ led to an oscillatory increase and 40 mM K⁺ to a plateau of [Ca²⁺]i superimposed on the [Ca²⁺]i elevated by sulfonylurea plus TEA. Raising K⁺ to 15 or 40 mM in the presence of sulfonylurea (±TEA) led to a fast further increase of insulin secretion. This was reduced to basal levels by nifedipine or CoCl₂. The effects of 15 mM K⁺ on depolarization, action currents, and insulin secretion were mimicked by adding 35 mM Cs⁺ and those of 40 mM K⁺ by adding 35 mM Rb⁺, in parallel with their ability to substitute for K⁺ as permeant cation. In conclusion, the alkali metals K⁺, Rb⁺, or Cs⁺ concentration-dependently transform the pattern of Ca²⁺ influx into the β-cell and may thus generate stimuli of supraphysiological strength for insulin secretion.
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Affiliation(s)
- M Belz
- Institute of Pharmacology and Toxicology, University of Braunschweig, Braunschweig, Germany
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Zhang Y, Liu Y, Qu J, Hardy A, Zhang N, Diao J, Strijbos PJ, Tsushima R, Robinson RB, Gaisano HY, Wang Q, Wheeler MB. Functional characterization of hyperpolarization-activated cyclic nucleotide-gated channels in rat pancreatic beta cells. J Endocrinol 2009; 203:45-53. [PMID: 19654142 PMCID: PMC2876733 DOI: 10.1677/joe-09-0068] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate pacemaker activity in some cardiac cells and neurons. In the present study, we have identified the presence of HCN channels in pancreatic beta-cells. We then examined the functional characterization of these channels in beta-cells via modulating HCN channel activity genetically and pharmacologically. Voltage-clamp experiments showed that over-expression of HCN2 in rat beta-cells significantly increased HCN current (I(h)), whereas expression of dominant-negative HCN2 (HCN2-AYA) completely suppressed endogenous I(h). Compared to control beta-cells, over-expression of I(h) increased insulin secretion at 2.8 mmol/l glucose. However, suppression of I(h) did not affect insulin secretion at both 2.8 and 11.1 mmol/l glucose. Current-clamp measurements revealed that HCN2 over-expression significantly reduced beta-cell membrane input resistance (R(in)), and resulted in a less-hyperpolarizing membrane response to the currents injected into the cell. Conversely, dominant negative HCN2-AYA expression led to a substantial increase of R(in), which was associated with a more hyperpolarizing membrane response to the currents injected. Remarkably, under low extracellular potassium conditions (2.5 mmol/l K(+)), suppression of I(h) resulted in increased membrane hyperpolarization and decreased insulin secretion. We conclude that I(h) in beta-cells possess the potential to modulate beta-cell membrane potential and insulin secretion under hypokalemic conditions.
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Affiliation(s)
- Yi Zhang
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
- Address correspondence to: Dr. Y Zhang, Departments of Physiology and Medicine, Room 7310, Medical Sciences Building, University of Toronto, 1 King’s College Circle, Toronto, ON, Canada M5S 1A8 Tel: (416)-978-7160; Fax: (416)-978-8765; . Dr. Q Wang, St. Michael’s Hospital, Room 7005, Queen Wing, 30 Bond Street, Toronto, ON,, Canada M5B 1W8. Tel: (416) 864-6060 x6767; Fax: (416) 864-6043;
| | - Yunfeng Liu
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
| | - Jihong Qu
- Department of Pharmacology, Columbia University, New York, U.S.A
| | - Alexandre Hardy
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
| | - Nina Zhang
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, Li Ka-Shing Knowledge Institute, St Michael’s Hospital, Toronto, Canada
| | - Jingyu Diao
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
| | - Paul J. Strijbos
- Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Harlow CM19 5AW, UK
| | - Robert Tsushima
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
| | | | - Herbert Y. Gaisano
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
| | - Qinghua Wang
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, Li Ka-Shing Knowledge Institute, St Michael’s Hospital, Toronto, Canada
- Address correspondence to: Dr. Y Zhang, Departments of Physiology and Medicine, Room 7310, Medical Sciences Building, University of Toronto, 1 King’s College Circle, Toronto, ON, Canada M5S 1A8 Tel: (416)-978-7160; Fax: (416)-978-8765; . Dr. Q Wang, St. Michael’s Hospital, Room 7005, Queen Wing, 30 Bond Street, Toronto, ON,, Canada M5B 1W8. Tel: (416) 864-6060 x6767; Fax: (416) 864-6043;
| | - Michael B. Wheeler
- Departments of Physiology and Medicine, University of Toronto, Ontario, Canada
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El-Kholy W, MacDonald PE, Fox JM, Bhattacharjee A, Xue T, Gao X, Zhang Y, Stieber J, Li RA, Tsushima RG, Wheeler MB. Hyperpolarization-activated cyclic nucleotide-gated channels in pancreatic beta-cells. Mol Endocrinol 2006; 21:753-64. [PMID: 17158221 DOI: 10.1210/me.2006-0258] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels mediate the pacemaker current (Ih or If) observed in electrically rhythmic cardiac and neuronal cells. Here we describe a hyperpolarization-activated time-dependent cationic current, beta-Ih, in pancreatic beta-cells. Transcripts for HCN1-4 were detected by RT-PCR and quantitative PCR in rat islets and MIN6 mouse insulinoma cells. beta-Ih in rat beta-cells and MIN6 cells displayed biophysical and pharmacological properties similar to those of HCN currents in cardiac and neuronal cells. Stimulation of cAMP production with forskolin/3-isobutyl-1-methylxanthine (50 microM) or dibutyryl-cAMP (1 mM) caused a significant rightward shift in the midpoint activation potential of beta-Ih, whereas expression of either specific small interfering (si)RNA against HCN2 (siHCN2b) or a dominant-negative HCN channel (HCN1-AAA) caused a near-complete inhibition of time-dependent beta-Ih. However, expression of siHCN2b in MIN6 cells had no affect on glucose-stimulated insulin secretion under normal or cAMP-stimulated conditions. Blocking beta-Ih in intact rat islets also did not affect membrane potential behavior at basal glucose concentrations. Taken together, our experiments provide the first evidence for functional expression of HCN channels in the pancreatic beta-cell.
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Affiliation(s)
- Wasim El-Kholy
- Department of Medicine, University of Toronto, Toronto, Canada M5S 1A8
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Braverman ER, Sohler A, Pfeiffer CC. Cesium chloride: preventive medicine for radioactive cesium exposure? Med Hypotheses 1988; 26:93-5. [PMID: 3412208 DOI: 10.1016/0306-9877(88)90058-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cesium is produced in high yield fission of uranium and plutonium. Radioactive cesium needles are a radiation hazard for radiotherapists. In this age of nuclear reactors, i.e. Chernobyl, radioactive cesium exposure may be a growing problem. Furthermore, there are numerous therapeutic potentials for cesium therapy, i.e. cancer, depression and schizophrenia. We explored the clearance of cesium in man and found that an oral dose of 50 mg maintains elevated blood cesium levels for 80 days. Cesium is accumulated mainly in the red blood cell fraction. Larger doses (6-9 grams) produce no observed harmful effects and maintain elevated blood levels of cesium for more than a year. Our data suggests there is a threshold of maximum cesium saturation in blood; if maintained, any additional cesium exposure, i.e. radioactive cesium, would be excreted at a more rapid rate. It is probable that large cesium doses can protect against radiation toxicity by blocking sites on red blood cells and thereby result in increased excretion and clearance of the radioactive forms of cesium. This hypothesis should be easily testable in laboratory animals.
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Affiliation(s)
- E R Braverman
- Princeton Brain Bio Center, Skillman, New Jersey 08558
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Paolisso G, Sgambato S, Passariello N, Pizza G, Torella R, Tesauro P, Varricchio M, D'Onofrio F. Plasma glucose lowering effect of sparteine sulphate infusion in non-insulin dependent (type 2) diabetic subjects. Eur J Clin Pharmacol 1988; 34:227-32. [PMID: 3396617 DOI: 10.1007/bf00540948] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sparteine sulphate, given i.v. as a bolus of 15 mg/ml plus 90 mg in 0.9% NaCl 100 ml over 60 min, increases plasma insulin and decreases plasma glucose and adrenaline in non-insulin dependent (Type II) diabetic subjects. The hypoglycaemic effect was also evident in the presence of a high plasma glucose level produced by Biostator changing glucose infusion from 20.2 +/- 2.8 to 26.4 +/- 4.2 mg.kg-1.min-1 (p less than 0.01), and it was potentiated by simultaneous infusion of arginine. No additional effect of sparteine on the peripheral sensitivity to insulin were detected by the euglycaemic, hyperinsulinaemic glucose clamp technique, as the glucose infusion rate (3.1 +/- 0.8 vs 2.6 +/- 1.2 mg.kg-1.min-1) was not statistically significant different in the last 60 min of the experiment. It is concluded that sparteine sulphate enhances beta-cell secretion, causing a fall in the plasma glucose concentration.
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Affiliation(s)
- G Paolisso
- Istituto di Gerontologia e Geriatria, Naples, Italy
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Sgambato S, Paolisso G, Passariello N, Varricchio M, D'Onofrio F. Effect of sparteine sulphate upon basal and nutrient-induced insulin and glucagon secretion in normal man. Eur J Clin Pharmacol 1987; 32:477-80. [PMID: 3305040 DOI: 10.1007/bf00637673] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Infusion of a therapeutic dose of sparteine sulphate, increased the basal plasma insulin level and lowered plasma glucose. When an intravenous glucose tolerance test was performed with the infusion, the total insulin AUC was significantly larger than in absence of sparteine (2025 vs 1464 microU/ml X min), plasma glucose levels were lower and improved glucose utilization was observed (kg:1.55 vs 1.39%). In the presence of arginine, sparteine sulphate stimulated both beta and alpha cells, increasing both the total insulin (1907 vs 1516 microU/ml X min p less than 0.02) and total glucagon AUCs (7616 +/- 654 vs 6789 +/- 707 pg/ml X min p less than 0.01). Thus, sparteine sulphate increased both basal and nutrient-induced insulin and glucagon secretion in normal man.
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Henquin JC, Schmeer W, Nenquin M, Meissner HP. Effects of a calcium channel agonist on the electrical, ionic and secretory events in mouse pancreatic B-cells. Biochem Biophys Res Commun 1985; 131:980-6. [PMID: 3902016 DOI: 10.1016/0006-291x(85)91336-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The changes in pancreatic B-cell function produced by a Ca channel agonist, the dihydropyridine derivative CGP 28392, have been studied with mouse islets. CGP 28392 (5 microM) modified the electrical activity induced in B-cells by 10 mM glucose: the duration and the amplitude of the slow waves of membrane potential increased, but the overall spike activity decreased. Simultaneously, CGP 28392 markedly increased insulin release and 45Ca2+ efflux, and slightly accelerated 86Rb+ efflux from islet cells. These latter effects were abolished by omission of extracellular Ca2+. Qualitatively similar changes were observed at 15 mM glucose, whereas CGP 28392 was ineffective at 3 mM glucose. These results strongly suggest that an influx of Ca2+ contributes to the slow waves of membrane potential triggered by glucose, and underline the importance of this influx of Ca2+ for the control of insulin release by the sugar.
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