Volume and Composition of Pilocarpine- and Isoproterenol-stimulated Submandibular Saliva of Early Postnatal Rats

Abstract

Submandibular saliva was collected from early postnatal rats by cannulation of the main excretory duct of individual glands after i.p. injections of pilocarpine (10 mg/kg body weight) or isoproterenol (10 mg/kg body weight). With this method of saliva collection, a secretory response to pilocarpine was observed at two wk of age. The average weight of 40 glands was 35.6 ± 1.6 mg, and the average volume of saliva secreted in 60 min was 32 ± 2.2 μl. By three wk of age, the gland had approximately doubled in size (average weight of 39 glands = 61.9 ± 3.1 mg), and the average total volume of saliva secreted in 60 min was more than three times larger (120.4 ± 10.5 μl) than that secreted by two-week-old rats. The relationship between electrolyte (Na⁺, K+, Ca⁺⁺ ) and protein concentrations and rate of flow was similar to that observed in pilocarpine-stimulated adult saliva, and did not differ appreciably in the saliva of two-and three-week-old animals. A measurable secretory response to isoproterenol was observed at three wk of age when saliva was collected by duct cannulation. The average total volume of saliva secreted in 60 min was 48 ± 3.1 μl, and salivary Na⁺ and K⁺ concen trations, and their relationship to flow rate, were similar to those of isoproterenol-stimulated adult saliva. Saliva Ca⁺⁺ and protein concentrations were also generally similar to those of isoproterenol-stimulated adult saliva. Total protein output (in 60 min) was 2½ times greater in three-week-old rats with isoproterenol stimulation (compared to pilocarpine stimulation), but was significantly smaller than that of isoproterenol-stimulated adult glands. It is concluded that the submandibular gland of early postnatal rats is capable of secreting saliva in vivo following cholinergic and β-adrenergic stimulation, and that this ability corresponds with the appearance of the corresponding autonomic receptors, but precedes cytodifferentiation, Ductal transport of electrolytes is well-developed at this stage of postnatal development, but fluid and protein output is smaller than in adult glands and requires full morphological maturation of acinar cells.

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References

Bylund, D.B. ; Martinez, J.R. ; Camden , J. ; and Jones, S.B. : Autonomic Receptors in the Developing Submandibular Gland of Neonatal Rats, Arch Oral Biol 27:945-950, 1982.

Martinez, J.R. and Camden, J. : In vitro Release of K+ from the Developing Submandibular Gland of Early Postnatal Rats, Arch Oral Biol 27:939-944, 1982.

Schneyer, L.H. and Schneyer, C.A. : Secretion by Salivary Glands Deficient in Acini, Am J Physiol 201:939-942, 1961.

Martinez, J.R. ; Adshead, P.C. ; Quissell , D.O. ; and Barbero, G.J. : The Chronically Reserpinized Rat as a Possible Model for Cystic Fibrosis: 11. Composition and Cilioinhibitory Effects of Submaxillary Saliva, Pediat Res 9 :470-475, 1975.

Martinez, J.R. ; Quissell, D.O. ; Wood , D.L. ; and Giles, M. : Abnormal Secretory Response to Parasympathomimetic and Sympathomimetic Stimulation from the Submaxillary Gland of Rats Treated with Reserpine, J Pharmacol Exp Ther 194:384-395, 1975.

Young, J.A. and Van Lennep, E.W. : Transport in Salivary and Salt Glands. In: Membrane Transport in Biology, Giebisch, G. , Tosteson, D.C. , and Ussing, H.H. , Eds., New York: Springer-Verlag, pp. 563-692, 1979.

Schneyer, C.A. and Hall, H.D. : Autonomic Pathways Involved in a Sympathetic-like Action of Pilocarpine on Salivary Composition, Proc Soc Exp Biol Med 121:96-100, 1966.

Lowry, O.H. ; Rosebrough, N.F. ; Farr, A.L. ; and Randall, R.J. : Protein Measurement with the Folin Phenol Reagent, J Biol Chem 193:265-278, 1951.

Jacoby, F. and Leeson, C.R. : The Postnatal Development of the Rat Submaxillary Gland, J Anat 93:201-216, 1959.

10.

Leeson, C.R. and Jacoby, F. : An Electron Microscopic Study of the Rat Submaxillary Gland During Its Postnatal Development and in the Adult, J Anat 93:287-299, 1959.

11.

Cutler, L.S. and Chaudhry, A.P. : Cytodifferentiation of the Acinar Cells of the Rat Submandibular Gland, Develop Biol 41:31-41,1974.

12.

Cutler, L.S. ; Christian, C.P. ; and Bottaro, B. : Development of Stimulus-secretion Coupling in Salivary Glands, Methods Cell Biol 23:531-545, 1981.

13.

Holzgreve, H. ; Martinez, J.R. ; and Vogel, A. : Micro-puncture and Histologic Study of Submaxillary Glands of Young Rats, Pflugers Arch 290:134-143, 1966.

14.

Martin, C.J. and Young, J.A. : A Microperfusion Investigation of the Effects of a Sympathomimetic and a Parasympathomimetic Drug on Water and Electrolyte Fluxes in the Main Duct of the Rat Submaxillary Gland, Pflugers Arch 327: 303-323, 1971.