Acetylcholine-induced responses in the salivary gland cells of Helisoma trivolvis.

This study describes the actions of acetylcholine (ACh) on the salivary gland cells of Helisoma. Perfusion of the salivary gland cells with ACh produces a long-lasting depolarization accompanied by an increase in the input conductance of the gland cells. The depolarization is often followed by a long-lasting hyperpolarization. Carbamylcholine, tetramethylammonium, and choline also produce depolarizing responses. Nicotine and pilocarpine produce only a small depolarization in the gland cells. The following cholinergic antagonists are effective in blocking the gland-cell response to ACh: tetraethylammonium, atropine, hexamethonium, d-tubocurarine, and strychnine. A new preparation, the "isolated acinus," was utilized to obtain the reversal potential of the ACh response. The mean reversal potential in 10 preparations was -7 +/- 8 mV. The depolarizing phase of the response is dependent on the presence of both external calcium and external sodium ions. The long-lasting hyperpolarization is produced by the activity of an electrogenic sodium-potassium pump. The properties of the acetylcholine receptors on the salivary gland cells of Helisoma are compared with those described in other gastropod preparations.