Secretion of electrolytes, protein and urea by the mandibular gland of the common wombat (Vombatus ursinus).

Saliva was collected from the mandibular glands of anaesthetized common wombats (Vombatus ursinus) to ascertain maximal flow rates, salivary composition and possible adaptations, particularly PO4(3-) secretion, to assist digestion. After temporary catheterization of the main duct through its oral opening, salivary secretion was evoked at flow rates ranging from 0.02 +/- 0.002 (+/- SEM) ml.min-1 (0.7 +/- 0.07 microliter.min-1.kg body weight-1) to 0.4 +/- 0.05 ml.min-1 (14 +/- 1.9 microliters.min-1.kg body weight-1) by ipsilateral intracarotid infusion of acetylcholine. The [Na+] (15 +/- 5.1 to 58 +/- 8.6 mmol.l-1) and [HCO3-] (35 +/- 1.9 to 60 +/- 1.9 mmol.l-1) were positively correlated with salivary flow rate. The [K+] (58 +/- 5.2 to 30 +/- 2.4 mmol.l-1), [Ca2+] (10.4 +/- 1.67 to 4.1 +/- 0.44 mmol.l-1), [Mg2+] (0.94 +/- 0.137 to 0.17 +/- 0.032 mmol.l-1), [Cl-] (71 +/- 9.2 to 45 +/- 6.0 mmol.l-1), [urea] (9.3 +/- 0.79 to 5.1 +/- 0.54 mmol.l-1), H+ activity (29 +/- 1.6 to 17 +/- 1.6 nEq.l-1) and amylase activity (251 +/- 57.4 to 92 +/- 23.3 mu kat.l-1) were negatively correlated with flow. Both concentration and osmolality fell with increasing flow at the lower end of the flow range but osmolality always increased again by maximal flow whereas the relation between protein and flow was not consistent at the higher levels of flow and stimulation. Salivary [PO4(3+)] was not correlated with flow and at 3-14% of the plasma concentration was extremely low.(ABSTRACT TRUNCATED AT 250 WORDS)