A simple technique to simultaneously assess activity at histamine H1- and H2-receptors in vivo

A technique is described that allows simultaneous and quantitative assay of the action of agonists and antagonists at histamine H1- and H2-receptors in anesthetized guinea pigs. The principle of the technique is based on H1-receptor bronchoconstriction and H2-receptor tachycardia. Studies have been made to assay antagonists at either receptor and provide simultaneous evidence of selectivity or to assay combined antagonists such as Smith Kline & French 93319. Studies with histamine receptor agonists provide evidence of the potency and selectivity of these compounds relative to histamine.