<prompt> Gastric secretion is increased by all exceptHistamineAcetylcholineGastrinHCI  <response>: Gastrin, histamine, and acetylcholine are the 3 agonists of the parietal cells.Gastrin and acetylcholine promote secretion by elevating cytosolic free calcium concentration.Histamine increases intracellular cAMP.Both this pathways together have more than additive effect on secretion rates Ref: Ganong;s Review of medical physiology, 23 rd edition, page 434 