The physiological characters of the sensory nerves from the submandibular gland were studied.In a preliminary experiment on a human sub ject, sensations which were induced by application of a back-pressure to the submandibular duct was evaluated. A swollen sensation was felt in the sublingual area of the floor of the mouth at 60 mmHg pressure, and pain localized in the submandibular gland region was elicited at 90 mmHg.The main experiments were on anesthetized dogs. A small tube was inserted into the duct of the submandibular gland and this was connected to a balloon pump (pressure pump) and to an electric manometer. To stimulate ordinary salivary secretion 1% pilocarpine (0.02 ml/kg) was injected intravenously, and in some experiments a back-pressure was also applied to the gland. The pressure curves and electrical activities of single fibers of the submandibular branch of the chorda tympani nerve were recorded simultane-ously.During salivary secretion induced by pilocarpine and during application of a back-pressure to the duct, the electrical activity of certain fibers in the submandibular branch of the chorda tympani was markedly facilitated following increase in internal pressure in the gland.There were found to be two types of baro-receptive fibers in the submandibular branch of the chorda tympani. One was the type which showed a slow adaptive response and the discharge of this type increased with increase in the ductal pressure. The other type showed a fast adaptive response and responded only to a certain definite level of internal pressure in the duct.These results suggest that baro-receptors in the ductal structures of the salivary gland may send information about the state of ductal dilatation during salivary secretion.
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Kawamura et al. (1964) studied this question.