Acetylcholine-induced transport of Na⁺ and K⁺ in the perfused cat submandibular gland

Summary

ACh-induced changes in the venous concentrations of Na⁺ and K⁺ have been studied in the perfused cat submandibular gland. ACh caused a transient decrease in the venous Na⁺ concentration which was smaller and of shorter duration than the well established increase in K⁺ concentration (Burgen [2]), but beginning at the same time. Subsequently a more pronounced increase in the Na⁺ concentration occurred.

With ouabain (10⁻⁴ M) in the perfusion fluid the ACh-induced decrease in Na⁺ concentration was identical with the increase in K⁺ concentration, which remained unchanged. Subsequent changes in directions opposite to those induced initially were abolished by ouabain.

With inulin as a reference for water movement it was shown that the ACh-induced decrease in venous Na⁺ concentration represents an influx of Na⁺ into the glandular cells.

The amount of K⁺ released from the glands by ACh decreased with increasing arterial K⁺ concentration.

It was concluded that ACh by increasing the permeability of the glandular cell membranes to Na⁺ and K⁺ elicited a passive influx of Na⁺ and a passive efflux of K⁺. The consequent rise in intracellular Na⁺ concentration may play an important role in ACh-induced salivary secretion.