TOPICS: Histamine receptors, histamine H1 receptor (H1), histamine H2 receptor (H2), bronchoconstriction, vasodilation, acid, GERD, vasopressin receptors, vasopressin V1 receptors (V1), vasopressin V2 receptors (V2), vasoconstriction, aquaporins, collecting tubule, antidiuretic hormone (ADH)