A difference in pharmacological properties of histamine receptors in rabbit aorta and basilar artery

An interaction of Ca entry blockers, D600 and diltiazem, with histamine receptors was tested in rabbit aorta and basilar artery. D600 caused a parallel rightward shift of the concentration response curve for histamine. The slope values from Schild plot analysis in aorta were not different from unity. Dibenamine pretreatment caused reduction of maximum response to histamine in aorta. Such reduction was diminished markedly by the presence of D600 or chlorpheniramine in aorta but not in basilar artery. However, diltiazem did not influence the concentration response curve for histamine. These findings suggest that pharmacological property of histamine receptors in rabbit aorta is distinct from that in basilar artery. Furthermore diltiazem seems not to interact with histamine receptors in both vascular tissues.