Structureactivity characterization of an H2-receptor antagonist, 3-amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]- cis-2-butenylamino]-3-cyclobutene-1,2-dione hydrochloride (IT-066), involved in the insurmountable antagonism against histamine-induced positive chronotropic action in guinea pig atria. - Kijima, H; Isobe, Y; Muramatsu, M (Biochem Pharmacol, 1998)