Calcium and the control of potassium efflux in the sublingual gland.

The effects of cholinergic stimulation on K efflux from rat sublingual gland slices was investigated. The sublingual gland slices appeared stable on incubation as indicated by electrolyte content and ultrastructural analysis. Carbachol induced a biphasic increase in release of 86Rb (an index of K efflux); a transient phase lasting 2--4 min was followed by a sustained (or slowly falling) phase. Both phases of the response were blocked by atropine, but only the sustained phase was blocked by omission of Ca or by the addition of LaCl3. The divalent cationophore A-23187 produced a Ca-dependent release of 86Rb. Substance P stimulated a biphasic release of 86Rb, similar to that obtained with carbachol, but epinephrine did not. The response to substance P demonstrated a Ca dependence similar to that of carbachol. When a transient response to carbachol was elicited, no transient response to carbachol was elicited, no transient response to substance P could be obtained. This suggests that the receptors for these agonists may reside in the same cells. Also, the magnitude of the responses suggests that most of the affected cells are probably the mucous elements of the sublingual gland.