- Alterations of Plasma Atrial Natriuretic Peptide and its mRNA in Non-insulin Dependent Diabetic Model of Rats.
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Byeong Dae Yoo, Won Kyun Park, Young Su Hong, Dae Kyu Song, Jae Hoon Bae
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Korean Diabetes J. 2000;24(4):421-430. Published online January 1, 2001
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 Abstract
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- BACKGROUND
Diabetes mellitus has led to change in fluid and electrolyte balance and consequently affected blood volume and blood pressure. These changes can trigger the secretion and synthesis of atrial natriuretic peptide (ANP) from both atrial and extra-atrial tissues. ANP plays an important role in the regulations of body fluid balance and blood pressure. Therefore, this study was carried out to elucidate whether or not atrial and extra-atrial synthesis of ANP is influenced in experimental non-insulin dependent diabetes mellitus (NIDDM) rats. METHODS: Neonatal rats were induced into NIDDM rats by single injection of streptozotocin (80 mg/kg). Plasma ANP level was measured by the use of radioimmunoassay method and the ANP mRNA expressions from the right atrium, left ventricle, hypothalamus and kidney were analyzed by reverse transcription- polymerase chain reaction with [32P]-dCTP at 8 weeks after injection of streptozotocin or citrate buffer. RESULTS: Blood glucose was more significantly increased at 2 hours after glucose loading in NIDDM rats than control rats. Plasma concentration of ANP tended to significantly increase in NIDDM rats compared with control rats. The expressions of ANP mRNA from each tissue were observed in different patterns. Right atrial ANP mRNA expression revealed non-significant increasing trend in NIDDM rats, whereas left ventricular ANP mRNA did not have difference. However, both hypothalamic and renal ANP mRNA expressions in NIDDM rats were significantly increased. CONCLUSION: These results indicate that the enhanced expressions of hypothalamic and renal ANP mRNA act as an important regulator of electrolytes and body fluid volume in neonatally streptozotocin-induced NIDDM rats.
- Differential Effects of Palmitate and Docosahexaenoic acid on ATP-sensitive K+ Channel Activity of Pancreatic beta-cells.
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Yong Woon Kim, Kyeung Oh Doh, Dae Kyu Song, Jae Hoon Bae, Won Kyun Park, Kyu Jang Won, Hyoung Woo Lee, Suck Kang Lee
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Korean Diabetes J. 1999;23(6):768-776. Published online January 1, 2001
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Abstract
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- BACKGROUND
Elevated levels of free fatty acids markedly enhance insulin secretion. However, dietary polyunsaturated fatty supplementation decrease insulin secretion. The effects of different type of fatty acids on cultured pancreatic beta cell remain controversy. Therefore, the specific goal of this study was to confirm the effect of palmitate and docosahexaenoic acid (DHA) on pancreatic beta-cells. We measured ATP-sensitive K+ (KATP) channel activity by patch clamp technique. METHOD: Pancreatic beta-cells were isolated from male Sprague-Dawley rats and cultured on the cover glass in the culture media. KATP channel activity of pancreatic beta-cells were measured by the cell-attached mode of the patch clamp technique. We treated 30 micrometer of palmitate and DHA dissolved with 3% albumin solution. RESULT: 30 micrometer of palmitate inhibited KATP channel activity. Moreover, after additions of 5 and 10 mM glucose, additional and dose dependent inhibitory effects were revealed. However, 30 micrometer of DHA did not have these additional inhibitory effect treated with 5 and lOmM glucose. CONCLUSION: Palmitate as a saturated fatty acid inhibited activity of KATP channel and increased inhibitory effect of glucose on this channel activity, however, DHA as a polyunsaturated fatty acid attenuated inhibitory effect of glucose on this channel activity.
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