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) stimulate 45Ca2+ uptake into isolated cells of rat submandibular galnd and parotid glands. In the presence of the alpha-adrenoreceptor blocking agent phentolamine, adrenaline stimulation of 45Ca2+ uptake is abolished. The beta-adrenergic stimulant isoproterenol has no effect on 45Ca2+ uptake. Carbamylcholine induced 45Ca2+ uptake is inhibited by atropine. The Ca2+ ionophore A23187 stimulates 45Ca2+ uptake, whereas dibutyryl cyclic adenosine 3',5'-monophosphate and dibutyryl cyclic guanosine 3',5'-monophosphate have no effect on 45Ca2+ uptake. A graphical analysis of the 45Ca2+ uptake curves reveals at least two phases: a fast phase and a slow phase, both of which are stimulated by adrenaline and carbamylcholine. The 45Ca-exchangeable pool size is increased by adrenaline and carbamylcholine in both the fast and the slow phases. These results suggest that alpha-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+.