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NH4Cl and protein metabolism in human gingival fibroblasts
Abstract:
The biologic effect of ammonia was studied in cultures of fibroblasts isolated from human gingiva, NH4Cl in the range 2-20 mM was found to exhibit a concentration dependent growth inhibitory effect, with a delayed action which was most pronounced at low concentrations. Concomitant with the growth inhibitory effect a significant cellular accumulation of protein was evident. No effects on protein synthesis in general, as measured by 14C-proline incorporation, was found, whereas some inhibitory effect on collagen biosynthesis was indicated. Secretion of 14C-collagen and other labeled proteins was not affected. The only pronounced effect of ammonia on metabolism of the 14C-labeled proteins was an inhibition of the intracellular degradation of newly synthesized collagen, the lysosomes being suggested as the site for this degradation.
Insights
Ammonia (NH4Cl) inhibits human gingival fibroblast growth in a dose-dependent manner, leading to protein accumulation. It specifically hinders intracellular collagen degradation, suggesting lysosomes are involved.
Area of Science:
- Biochemistry
- Cell Biology
- Toxicology
Background:
- Ammonia is a common metabolite with potential cellular effects.
- Fibroblasts play crucial roles in tissue structure and repair.
- Understanding ammonia's impact on gingival cells is relevant to oral health.
Purpose of the Study:
- To investigate the biologic effects of ammonia on human gingival fibroblast cultures.
- To determine the concentration-dependent effects of ammonia on cell growth and protein metabolism.
Main Methods:
- Culturing human gingival fibroblasts.
- Treating cultures with varying concentrations of ammonium chloride (NH4Cl).
- Measuring cell growth, protein synthesis (14C-proline incorporation), collagen biosynthesis, and intracellular protein degradation.
Main Results:
- Ammonia exhibited a concentration-dependent, delayed growth inhibitory effect on fibroblasts, most pronounced at low concentrations.
- Cellular protein accumulation was observed concurrently with growth inhibition.
- No general inhibition of protein synthesis was detected, but collagen biosynthesis showed some inhibition.
- Ammonia specifically inhibited the intracellular degradation of newly synthesized collagen.
Conclusions:
- Ammonia impacts human gingival fibroblast proliferation and protein metabolism.
- The primary metabolic effect observed is the inhibition of intracellular collagen degradation, likely within lysosomes.
- These findings suggest a potential role for ammonia in modulating extracellular matrix turnover in the gingiva.