Calcium ion uptake induced by cholinergic and ?-adrenergic stimulation in isolated cells of rat salivary glands

Abstract

Adrenaline (10⁻⁵ M) and carbamylcholine (10⁻⁴ M) stimulate⁴⁵Ca²⁺ uptake into isolated cells of rat submandibular gland and parotid glands. In the presence of the α-adrenoreceptor blocking agent phentolamine, adrenaline stimulation of⁴⁵Ca²⁺ uptake is abolished. The β-adrenergic stimulant isoproterenol has no effect on⁴⁵Ca²⁺ uptake. Carbamylcholine induced⁴⁵Ca²⁺ uptake is inhibited by atropine. The Ca²⁺ ionophore A23187 stimulates⁴⁵Ca²⁺ uptake, whereas dibutyryl cyclic adenosine 3′,5′-monophosphate and dibutyryl cyclic guanosine 3′,5′-monophosphate have no effect on⁴⁵Ca²⁺ uptake. A graphical analysis of the⁴⁵Ca²⁺ uptake curves reveals at least two phases: a fast phase and a slow phase, both of which are stimulated by adrenaline and carbamylcholine. The⁴⁵Ca-exchangeable pool size is increased by adrenaline and carbamylcholine in both the fast and the slow phases. These results suggest that α-adrenergic and cholinergic agonists act by increasing the rate of Ca²⁺ transfer into the cells of the parotid and submandibular salivary glands most probably through an increase of the cell membrane permeability for Ca²⁺.