The muscarinic receptor-mediated action of acetylcholine in the gastrulating chick embryo.

Abstract 1. 1. Some of the muscarinic receptor-mediated effects of acetylcholine in early chick embryo cells at stages three-four by Hamburger and Hamilton were studied. 2. 2. Acetylcholine increased the intracellular level of cGMP about two-fold. 3. 3. Acetylcholine raised the intracellular level of free calcium from the basal level of 120 nM to 140 nM. 4. 4. Atropine, a muscarinic antagonist, blocked both the above-mentioned responses.