Pharmacological evaluation of sheep lung strip

Abstract

Isolated sheep lung parenchymal strips responded to histamine > carbachol > PGF2a > 5‐HT with contractions, and to isoproterenol (Isop), and to large doses of epinephrine (E), norepinephrine (NE) and phenylephrine (PE) with relaxations. PGF2a‐contracted lung strip responded to PGE1 and PGE2 with relaxation. The strips which were partially contracted to histamine, PGF2a, 5‐HT and carbachol also responded to isop, E and NE with relaxations. Histamine responses were not modified by metiamide (an H2‐receptor antagonist). Mepyramine and atropine selectively antagonized contractions to histamine and carbachol, respectively. After β‐blockade with propranolol, lung strips responded to NE > E > PE > isop with contractions, which were inhibited or reversed by phentolamine and dibenzyline. It is concluded that H1 receptors are present in sheep peripheral airway smooth muscles, and that a‐ and β‐adrenoceptors mediate contraction and relaxation, respectively, in sheep lung strips.