Summary
After stimulation of the protein secretion by pilocarpine or feeding the rate of incorporation of [3H]-leucine increases in the acinar cells of the parotid gland of the rat while the secretory cells of the submandibular gland show a moderate decrease (Kuijper et al., 1975b). Since the rate of labelled amino acid incorporation depends on the specific radioactivity of the amino acid used, which is not easy to determine in vivo, experiments in vitro were performed to get an idea of the influence of this factor on the measured changes in [3H]-leucine incorporation.
In vitro both cell types showed a more pronounced but essentially identical reaction as in vivo. Since in these experiments the specific radioactivity of the extracellular leucine is the same whether fragments of stimulated or unstimulated glands incorporate the radioactive amino acid, the increase of incorporation in the parotid and the decrease in the submandibular cells cannot be ascribed to differences in specific radioactivity of leucine, unless the intracellular leucine pool should show great differences between secreting and non-secreting cells.
However, in vitro the submandibular gland cells under both conditions appear to use the extracellular leucine for their protein synthesis (or a small compartmentalized pool in rapid exchange with the extracellular pool). In the parotid cells the whole intracellular pool showed such a rapid exchange with the extracellular one that for practical reasons one may say that these cells, too, rely on the extracellular specific radioactivity of leucine in their protein synthesis.
We conclude that the rat parotid gland cells show a rapid and substantial increase of protein synthesis after stimulation of their enzyme secretion, while the submandibular gland cells do not.
Similar content being viewed by others
References
Babad, H., Ben-Zvi, R., Bdolah, A., Schramm, M.: The mechanism of enzyme secretion by the cell. Europ. J. Biochem. 1, 96–101 (1967)
Castle, J.D., Jamieson, J.D., Palade, G.E.: Radioautographic analysis of the secretion process in the parotid acinar cell of the rabbit. J. Cell. Biol. 53, 290–311 (1972)
Ekfors, T., Barka, T.: The effect of isoproterenol on protein synthesis in rat submandibular gland. Lab. Invest. 24, 197–202 (1971)
Enwonwu, C.O.: Restitution of secretory proteins as reflected by changes in polyribosomal organisation in salivary glands of rats treated with isoproterenol. Lab. Invest. 27, 199–208 (1972)
Grand, R.J., Gross, R.J.: Independent stimulation of secretion and protein synthesis in rat parotid gland. J. Biol. Chem. 244, 5608–5815 (1969)
Groot, E.C.B.M. de: The relation between synthesis and secretion of pepsinogen (summary in English). Thesis, Utrecht (1974)
Jamieson, J.D., Palade, G.E.: Synthesis, intracellular transport, and discharge of secretory proteins in stimulated pancreatic exocrine cells. J. Cell Biol. 50, 135–158 (1971)
Kramer, M.F., Poort, C.: Protein synthesis in the pancreas of the rat after stimulation of secretion. Z. Zellforsch. 86, 475–486 (1968)
Kuijper-Lenstra, A.H., Kramer, M.F.: Rate of protein synthesis in rat salivary gland cells after pilocarpine or feeding. I. Rate of (glyco)protein secretion from cells of mixed salivary glands. Cell Tiss. Res. 164, 435–446 (1975a)
Kuijper-Lenstra, A.H., Kramer, M.F., Venrooij, W.J. van: Rate of protein synthesis in rat salivary gland cells after pilocarpine or feeding. II. Protein synthesis in vivo in cells of the submandibular and parotid gland after secretion. Cell Tiss. Res. 164, 447–456 (1975b)
Lilly, J.H., Hans, S.S.: Secretory protein synthesis in the stimulated rat parotid gland. J. Cell Biol. 59, 708–721 (1973)
Morrisset, J.A., Webster, P.D.: In vitro and in vivo effects of pancreozymin, urecholine and cyclic AMP on rat pancreas. Amer. J. Physiol. 230, 202–208 (1971)
Morrisset, J.A., Webster, P.D.: Effects of fasting and feeding on protein synthesis by the rat pancreas. J. Clin. Invest. 51, 1–18 (1972)
Poort, C., Kramer, M.F.: Effect of feeding on the protein synthesis in mammalian pancreas. Gastroenterology 57, 689–696 (1969)
Robinovitch, M.R., Smuckler, E.A., Sreebny, L.M.: Protein synthesis in a cell-free system derived from the rat parotid gland. J. Biol. Chem. 244, 5361–5367 (1969)
Stenram, U., Hirschman, R.: Radioautographic studies of the protein synthesis in rat during protein deprivation and starvation. Acta Anat. 61, 445–453 (1965)
Venrooij, W.J. van, Kuijper-Lenstra, A.H., Kramer, M.F.: Interrelationship between amino acid pools and protein synthesis in the rat submandibular gland. Biochim. Biophys. Acta 312, 392–398 (1973)
Venrooij, W.J. van, Poort, C., Kramer, M.F., Jansen, M.T.: Relationship between extracellular amino acids and protein synthesis in vitro in the rat pancreas. Europ. J. Biochem. 30, 427–433 (1972)
Webster, P.D.: Effect of methacholine on pancreatic amylase synthesis. Gastroenterology 55, 375–385 (1968)
Webster, P.D., Tyor, M.P.: Effect of intravenous pancreozymin on amino acid incorporation in vitro by pancreatic tissue. Amer. J. Physiol. 211, 157–160 (1966)
Author information
Authors and Affiliations
Additional information
The authors acknowledge Mr. N.J. Tersteeg and Mr. F.B. Zwaan for their skilful care of the experimental animals; Mrs. G.W. Lucini-Best, Miss S.N.M. van Loenen and Mr. R. Dol for their valuable technical assistance; and Miss M.E. Huese for typewriting the manuscript.
Rights and permissions
About this article
Cite this article
Kuijper-Lenstra, A.H., Kramer, M.F. Rate of protein synthesis in rat salivary gland cells after pilocarpine or feeding. Cell Tissue Res. 164, 457–466 (1975). https://doi.org/10.1007/BF00219937
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00219937