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Gomes Castro AJ, Cazarolli LH, Bretanha LC, Sulis PM, Rey Padilla DP, Aragón Novoa DM, Dambrós BF, Pizzolatti MG, Mena Barreto Silva FR. The potent insulin secretagogue effect of betulinic acid is mediated by potassium and chloride channels. Arch Biochem Biophys 2018; 648:20-26. [PMID: 29704483 DOI: 10.1016/j.abb.2018.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 04/19/2018] [Accepted: 04/21/2018] [Indexed: 12/13/2022]
Abstract
Betulinic acid (BA) has been described as an insulin secretagogue which may explain its potent antihyperglycemic effect; however, the exact role of BA as an insulinogenic agent is not clear. The aim of this study was to investigate the mechanism of BA on calcium influx and static insulin secretion in pancreatic islets isolated from euglycemic rats. We found that BA triggers calcium influx by a mechanism dependent on ATP-dependent potassium channels and L-type voltage-dependent calcium channels. Additionally, the voltage-dependent and calcium-dependent chloride channels are also involved in the mechanism of BA, probably due to an indirect stimulation of calcium entry and increased intracellular calcium. Additionally, the downstream activation of PKC, which is necessary for the effect of BA on calcium influx, is involved in the full stimulatory response of the triterpene. BA stimulated the static secretion of insulin in pancreatic islets, indicating that the abrupt calcium influx may be a key step in its secretagogue effect. As such, BA stimulates insulin secretion through the activation of electrophysiological mechanisms, such as the closure of potassium channels and opening of calcium and chloride channels, inducing cellular depolarization associated with metabolic-biochemical effects, in turn activating PKC and ensuring the secretion of insulin.
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Affiliation(s)
- Allisson Jhonatan Gomes Castro
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Luisa Helena Cazarolli
- Universidade Federal da Fronteira Sul, Campus Universitário Laranjeiras do Sul, Laranjeiras do Sul, PR, Brazil
| | - Lizandra C Bretanha
- Departamento de Química, Centro de Ciências Físicas e Matemáticas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Paola Miranda Sulis
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Diana Patricia Rey Padilla
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil; Universidad Nacional de Colombia, Departamento de Farmácia, Facultad de Ciencias, Bogotá, Colombia
| | | | - Betina Fernanda Dambrós
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Moacir G Pizzolatti
- Departamento de Química, Centro de Ciências Físicas e Matemáticas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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Qi M, Luis V, Bilbao S, Omori K, Rawson J, McFadden B, Juan J, Nair I, Mullen Y, El-Shahawy M, Dafoe D, Kandeel F, Al-Abdullah IH. Sodium levels of human pancreatic donors are a critical factor for determination of islet efficacy and survival. Am J Physiol Endocrinol Metab 2015; 308:E362-9. [PMID: 25537495 DOI: 10.1152/ajpendo.00443.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Organs from hypernatremia (elevated Na+) donors when used for transplantation have had dismal outcomes. However, islet isolation from hypernatremic donors for both transplantation and research applications has not yet been investigated. A retrospective analysis of in vivo and in vitro islet function studies was performed on islets isolated from hypernatremic (serum sodium levels≥160 meq/l) and normal control (serum sodium levels≤155 meq/l) donors. Twelve isolations from 32 hypernatremic and 53 isolations from 222 normal donors were randomly transplanted into diabetic NOD Scid mice. Sodium levels upon pancreas procurement were significantly elevated in the hypernatremia group (163.5±0.6 meq/l) compared with the normal control group (145.9±0.4 meq/l) (P<0.001). The postculture islet recovery rate was significantly lower in the hypernatremia (59.1±3.8%) group compared with the normal (73.6±1.8%) group (P=0.005). The duration of hypernatremia was inversely correlated with the recovery rate (r2=0.370, P<0.001). Furthermore, the percentage of successful graft function when transplanted into diabetic NOD Scid mice was significantly lower in the hypernatremia (42%) group compared with the normal control (85%) group (P<0.001). The ability to predict islet graft function posttransplantation using donor sodium levels and duration of hypernatremia was significant (ROC analysis, P=0.022 and 0.042, respectively). In conclusion, duration of donor hypernatremia is associated with reduced islet recovery postculture. The efficacy of islets from hypernatremia donors diminished when transplanted into diabetic recipients.
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Affiliation(s)
- Meirigeng Qi
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Valiente Luis
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Shiela Bilbao
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Keiko Omori
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Jeffrey Rawson
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Brian McFadden
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Jemily Juan
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Indu Nair
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Yoko Mullen
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Mohamed El-Shahawy
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Donald Dafoe
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Fouad Kandeel
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
| | - Ismail H Al-Abdullah
- Department of Diabetes and Metabolic Diseases Research, Beckman Research Institute of the City of Hope, Duarte, California
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