Movements of Na∗ and K+ in slices of herring-gull salt gland

• 1.

  1. Fresh slices of salt gland from the herring gull contained approx. 290 mmoles 3⁺ and 350 mmoles Na⁺ per kg dry weight.

• 2.

  2. During incubation at 1° for up to 4 h there was a loss of some 75 mmoles K⁺ per kg dry weight and an equivalent gain of Na⁺; the slices did not swell significantly. The loss of K⁺ was not increased by incubation at 1° in a K⁺-free medium.

• 3.

  3. The rate of ²⁴Na⁺ efflux from the slices and the ability of the slices to maintain their Na⁺ and K⁺ contents during incubation at 25°, were both dependent upon aerobic conditions and the presence of K⁺ (5 mM) in teh medium, and were inhibited by ouabain (0.05 mM).

• 4.

  4. Methacholine (0.33 mM) induced a temporary stimulation of ²⁴Na⁺ efflux. This stimulation was smaller in the presence than in the absence of K⁺ in the medium, but the sum of the effects of K⁺ adn of methacholine in the presence of K⁺ was greater than the effect of methacholine alone in the K⁺-free medium.

• 5.

  5. Methacholine had no significant effect on the Na⁺ and K⁺ contents of the slices, but did cause a decrease in the specific radioactivity of the Na⁺ of the slices at 25°.

• 6.

  6. The results suggest that methacholine and K⁺ both act on salt-gland cells by increasing the permeability to Na⁺ and that, in addition, K⁺ stimulates a mechanism for coupled movements of Na⁺ adn K⁺