Secretion by the parotid gland of the sheep

Abstract

Secretion by the parotid gland of the sheep has been studied in acute preparations and by means of fistulae. The sheep is unusual in having a continuous flow of parotid saliva which increases in amount both with feeding and with cud chewing (Ellenberger & Hofmeister, 1887). As in the ox its parasympathetic nerve supply arrives via the buccal branch of the mandibular nerve as fine branches which go from the anterior border of the masseter muscle with the duct to the gland (Moussu, 1888(Moussu, , 1890, not via the auriculo-temporal nerve. Moussu demonstrated that after section of this nerve the gland continued to secrete and he attributed this continued secretion to a non-nervous mechanism postulated by Colin (1886). Eckhard (1893) who in 1867 (Eckhard, 1867), before Moussu's discovery, had convinced himself that there was no secretomotor nerve to the gland, held the view that it was due to the 'nature' of the gland.Eckhard (1893), after amplifying these observations and confirming Moussu's observation that stimulating the buccal branch of the mandibular nerve (henceforth referred to as Moussu's nerve) increased secretion, nevertheless stated that section of the nerve did not cause any reduction in the rapidity of secretion by the gland. This view has not been refuted, and is often quoted with the reservation that it requires confirmation (Langley, 1898, in Schafer's Physiology text-book; Babkin, 1944). It is associated with statements that salivary secretion in the ruminant is not stopped by atropine. However, the reduction by atropine of normal secretion to a lower rate is recognized by Babichev, Perstnov & Kulesco (1930) as indicating a biphasic secretomotor mechanism. In this paper we have endeavoured to establish with certainty the effect of the parasympathetic nerve on the gland.Another controversial matter is the effect of stimulation of the sympathetic fibre', to the parotid upon its secretory activity. Eckhard (1869) attacked the

The effect of variations in blood supply on the secretion rate and composition of parotid saliva in Na+‐depleted sheep

“…If, however, the sheep were taken out of its cage and gently secured on its side, the blood pressure rose to 100-130 mm Hg and in sheep P.F. 7, as in other sheep tested, this procedure inhibited the continuous secretion of parotid saliva characteristic of the ruminant, as also did continued stimulation of the cervical sympathetic in anaesthetized sheep (Coats et al 1956). Occlusion of the right (innervated) carotid loop for 3-10 min raised the blood pressure by 10-50 mm Hg.…”

“…16 the left superior cervical ganglion and a portion of the left cervical sympathetic trunk in the root of the neck were removed, and the left occipital arteryligated. The removal of the ganglion was confirmed histologically, and it was demonstrated at operation that stimulation of the cranial end of the divided sympathetic trunk did not cause the characteristic gush of parotid saliva (Coats, Denton, Goding & Wright, 1956). …”

Secretion by the parotid gland of the sheep: the relationship between salivary flow and composition

“…Care was taken that the saliva specimen was not contaminated with preformed saliva within the duct cannula, but it was certainly a mixture of saliva secreted during stimulation and preformed saliva within the intraglandular duct system. There was no method of accurately assessing the capacity of the intraglandular duct system, but cervical sympathetic stimulation (Coats et al 1956) indicated that the saliva specimen obtained was shows that the concentration changes were roughly reciprocal, but that the fluctuations in sodium concentration occurred at approximately twice the rate of the potassium fluctuations. The different time relationship is better illustrated in Fig.…”

“…Cannulation of the parotid duct, and the preparation of the parasympathetic nerve (Moussu'# nerve) for stimulation have been previously described (Coats, Denton, Goding & Wright, 1956 (Denton, 1956).…”

The rate of flow and composition of various salivary secretions in sheep and calves

“…A large fraction of this saliva is supplied by the parotid glands, which have been studied by many workers (Colin, 1886;Scheunert & Trautmann, 1921;Coats, Denton, Goding & Wright, 1956;Denton, 1957b;Kay, 1958). The parotid glands secrete rapidly and continuously, but the submaxillary glands secrete little except during feeding periods (Colin, 1886;Scheunert & Trautmann, 1921).…”