Ascorbic acid concentration in the lateral hypothalamus is related to plasma osmolality.
Microdialysis was used to measure extracellular ascorbic and uric acid concentrations in the lateral hypothalamus of water-restricted rats as they drank distilled water or 1.5% NaCl. Other water-restricted rats, not implanted with microdialysis probes, were decapitated 2 h after beginning to drink these fluids. Rats were inverted and their blood was collected for measurements of plasma osmolality and percent hematocrit. Results showed that drinking distilled water produced a significant increase in the ascorbic acid concentration but not in the uric acid concentration. Drinking 1.5% NaCl produced a significant decrease in the uric acid concentration but not in the ascorbic acid concentration. Drinking distilled water decreased mean osmolality from 306.0 to 291.5 mOsm/kg, whereas drinking 1.5% NaCl maintained mean osmolality at water-restricted levels. These results indicate that the extracellular fluid concentration of ascorbic acid in the lateral hypothalamus rises in response to a fall in plasma osmolality.
Mason
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PA
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA.
Dev
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BR
Freed
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CR
D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D004326:Drinking / Q000502:physiology; D004563:Electrochemistry; D007026:Hypothalamic Area, Lateral / Q000033:anatomy & histology / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley; D014527:Uric Acid / Q000097:blood; D014882:Water-Electrolyte Balance / Q000502:physiology
D014527:Uric Acid; D001205:Ascorbic Acid