Submandibular secretory and vascular responses to stimulation of the parasympathetic innervation in anesthetized cats.

Submandibular secretory responses to stimulation of the parasympathetic chorda-lingual nerve in anaesthetized cats have been investigated before, during, and after intracarotid infusion of endothelin-1 (ET-1), which reduced blood flow through the gland by 64+/-7%. Stimulation at different frequencies (2, 4, 8, and 16 Hz) evoked a frequency-dependent increase in the flow of submandibular saliva, sodium concentration and output, and output of both potassium and protein. The reduction in submandibular blood flow, which occurred in response to the infusion of ET-1, was associated with a decreased flow of saliva and a diminished output of both sodium and protein. The flow of saliva was linearly related to submandibular blood flow both in the presence and absence of ET-1. It is concluded that submandibular secretory responses to electrical stimulation of the parasympathetic innervation can be significantly attenuated by reducing the blood flow through the gland by ET-1 infusion, just as it is when the blood flow is reduced by hypotension.