Reactivity of isolated rat and canine pulmonary arteries to prostaglandins

Abstract

In this investigation, the sensitivity and contractility of isolated rat and canine pulmonary arteries to a variety of prostaglandin compounds (PGs) were studied. Based on EC50's and threshold concentrations, the contractile sensitivity of rat pulmonary arteries to PGs was; PGB 2⪢ PGA 2 > PGF 2σ ≊ PGE 2> PGB 1 ≊ PGAI 1⪢ PGF 1∝ ≊PGE 1 PGD 2. In terms of the ability to generate a maximum contractile responses on rat pulmonary arteries, the PGs were also variable, where PGB2 was the most potent and PGD 2the least potent agonist.None of these contractile responses were tachyphylactic on rat pulmonary arteries. Surprisingly, except for PGB 2, none of the PGs elicited reproducible contractile responses on canine pulmonary arteries.The present data, therefore, clearly indicate that there are species differences with respect to the contractile action of PGs on pulmonary vessels. In addition, these findings suggest that a clear structure-activity relationship exists for the contractile action of PGs on rat pulmonary arteries. The latter differential reactivity may be important in hypoxic pulmonary vasoconstriction and allergic hypersensitivity phenomena in certain mammals.