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Phosphate depletion impairs insulin secretion by pancreatic islets
X J Zhou1, G Z Fadda, A F Perna
1Division of Nephrology, University of Southern California School of Medicine, Los Angeles.
Kidney International
|January 1, 1991
Summary
Phosphate depletion impairs pancreatic islet insulin secretion, leading to glucose intolerance. This study directly demonstrates reduced insulin release in phosphate-depleted rats, identifying potential cellular mechanisms.
Area of Science:
- Endocrinology
- Metabolic Physiology
- Nutritional Science
Background:
- Phosphate depletion (PD) is linked to insulin resistance and glucose intolerance.
- Previous studies on PD's effect on insulin secretion are inconsistent and relied on indirect measures.
Purpose of the Study:
- To directly investigate the impact of phosphate depletion on insulin secretion by pancreatic islets.
- To explore the underlying mechanisms of PD-induced alterations in insulin secretion.
Main Methods:
- Intravenous glucose tolerance tests (IVGTT) in phosphate-depleted (PD) and pair-weighed (PW) rats.
- In vitro assessment of insulin secretion from isolated pancreatic islets.
- Evaluation of islet cellular factors, including ATP, ADP, cyclic AMP, and calcium levels.
Main Results:
- PD rats exhibited fasting hyperglycemia and abnormal IVGTT responses.
- Both early and late phases of glucose-stimulated insulin secretion were significantly reduced in PD rat islets.
- PD islets showed lower ATP content and ATP/ADP ratios, with elevated resting cytosolic calcium.
Conclusions:
- Phosphate depletion directly impairs pancreatic islet function, reducing glucose-induced insulin secretion.
- Altered islet energy metabolism (ATP/ADP ratio) and calcium handling may underlie these defects.
- These findings provide direct evidence for PD's role in glucose intolerance.