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Updated: Jul 28, 2026
Spinal Cord Electrophysiology
Published on: January 18, 2010
Sodium or chloride deficiency lowers muscle intracellular pH in growing rats
1Department of Nephrology, Children's National Medical Center, Washington, D.C. 20010, USA.
Insights
Sodium and chloride deficiencies in young rats led to reduced extracellular fluid volume, hyponatremia, and impaired growth. Muscle acidity increased, potentially hindering cell growth.
Area of Science:
- Physiology
- Nutritional Science
- Cell Biology
Background:
- Sodium and chloride deficiencies are linked to reduced extracellular fluid (ECF) volume and impaired growth in young individuals.
- In vitro studies show low sodium reduces growth factor-stimulated Na+/H+ exchange, intracellular pH (pHi), and DNA synthesis.
Purpose of the Study:
- To investigate the impact of chronic sodium and chloride deficiencies on growth, acid-base balance, and muscle pHi in young rats.
Main Methods:
- Growing rats were fed control, sodium-deficient, chloride-deficient, or calorie-restricted diets for 21 days.
- Muscle pHi was measured using 31phosphorus nuclear magnetic resonance spectroscopy.
Main Results:
- Sodium or chloride deficiency caused ECF volume contraction and hyponatremia, impairing growth in length and weight.
- Muscle pHi decreased significantly in both sodium-deficient and chloride-deficient groups.
- Calorie restriction impaired growth but did not affect muscle pHi.
Conclusions:
- ECF volume contraction and hyponatremia in sodium and chloride deficiency may lead to decreased muscle pHi.
- Reduced muscle pHi is a potential contributor to the observed retarded cell growth.
Abstract:
Sodium deficiency and chloride deficiency are associated with a contracted extracellular (ECF) volume and impaired growth in young children and growing rats. In cell culture, lowering sodium in the medium reduces growth factor-stimulated Na+/H+ exchange activity, intracellular pH (pHi), and DNA synthesis. We studied the effect of chronic sodium deficiency and chloride deficiency upon growth, extracellular acid base status, and muscle pHi in young rats. We fed growing rats for 21 days either a control diet, or one deficient in sodium (0.005%), chloride (0.005%), or calories. Muscle pHi was measured using 31phosphorus nuclear magnetic resonance spectroscopy. Rats fed either the sodium-deficient or chloride-deficient diet developed ECF volume contraction and hyponatremia; growth in length and weight was impaired. Muscle pHi was decreased (pHi = 7.074 +/- 0.006, 7.078 +/- 0.006 vs. control 7.100 +/- 0.002; P < 0.02). In calorie-restricted rats, growth was impaired but pHi was not affected (pHi 7.103 +/- 0.008). Metabolic alkalosis developed in the chloride-deficient group; acid base status was not affected in the sodium-deficient group. Despite differences in ECF acid base status, both groups had a low muscle pHi. We speculate that the low muscle pHi was a result of the ECF volume contraction and hyponatremia; low muscle pHi may contribute to retarded cell growth.
