Parasympathetic Neuro‐Effector Transmission and Functional Vasodilatation in the Submandibular Salivary Gland of Cats

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Abstract
The present study deals with the effect of different pharmacological agents on the secretory and vasodilator responses caused by stimulation of the chordo‐lingual nerve in cat submandibular salivary glands perfused under conditions of constant volume inflow.When the gland was perfused with red cellsiuspended in normal cat plasma or in kininogen‐free solutions, the vasodilator and secretory responses raused by stimulation of the chordo‐lingual nerve were mimicked by close arterial injections of acetylcholine. Atropine injected intravenously in doses of 0.5–1 mg/kg did not affect the chorda‐induced vasodilatation while salivary secretion was blocked. Increasing doses of atropine caused a successive reduction in the chorda‐mediated vasodilatation.Close arterial injections of isoprenaline caused vasodilatation, but no secretion of saliva. Propranolol in doses of 10–200 μg infused into the gland, abolished the effect of injected isoprenaline, but caused a small reduction of the chorda‐mediated vasodilatation. The combined action of propranolol and atropine depressed the long‐lasting vasodilator phase of chorda stimulation while the initial decrease in perfusion pressure was not affected.The findings suggest that the chordo‐lingual fibres to this gland all are cholinergic and that the nerve‐effector transmissions vary in their atropine sensitivity. The neuroglandular synapse responsible for secretion of watery saliva is easily blocked by atropine. The neuro‐vascular transmission and the neuro‐glandular connection responsible for release of kallikrein, are both relatively atropine‐resistant.
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