Muscarinic Receptors in Chromaffin Cell Cultures Mediate Enhanced Phospholipid Labeling but Not Catecholamine Secretion

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Abstract
The addition of either carbachol or muscarinic agonists to cultured bovine adrenal chromaffin cells results in a selective stimulation of phosphatidate (PhA) and phosphatidylinositol (PhI) labeling from 32Pi and [3H]glycerol that can be inhibited by the inclusion of atropine, but not d-tubocurarine. Increased catecholamine secretion is observed on the addition of carbachol or nicotinic agonists and is inhibited by d-tubocurarine but not by atropine. Added Ca2+ is essential for catecholamine secretion but not for stimulated phospholipid labeling. Chelation of endogenous Ca2+ with EGTA [ethylene glycol bis .beta. aminoethyl ether] does inhibit the stimulated phospholipid labeling. Stimulated phospholipid labeling in the bovine chromaffin cell and catecholamine secretion are apparently separate and distinct processes.