“…Several laboratories have reported that pretreatment of chromaffin cells with pertussis toxin (PTX) enhances both basal secretion from those cells and secretion in response to secretagogues including acetylcholine, nicotine, muscarinic agonists, and elevated K+ (Tanaka et al, 1987;Brocklehurst and Pollard, 1988;Ohara-Imaizumi et al, 1988, 1990Sasakawa et al, 1988;O'Sullivan and Burgoyne, 1989;Bansal et al, 1990;Sontag et al, 1991). Although three G-protein substrates for PTX-catalyzed ADP ribosylation have been identified in chromaffin cells (Toutant et al, 1987), the mechanism by which PTX produces this secretion-enhancing effect is unclear.…”