Influence of nitrovasodilators on bovine pulmonary histamine release

The organic nitrates and related nitrovasodilators are relaxants of vascular and airway smooth muscle. Very little information is currently available regarding the influence of nitrates and related nitrovasodilators on pulmonary autacoid release. This study examined the influence of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside on histamine release from bovine lung mince. Spontaneous histamine release from bovine lung mince was not altered by 0.1 nM to 1 microM glyceryl trinitrate, isosorbide dinitrate or sodium nitroprusside. Glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside produced a concentration-dependent decrease in A23187 (10 microM) stimulated histamine release. Glyceryl trinitrate also inhibited histamine liberation following the addition of compound 48/80. Further studies indicated that the inhibitory action of glyceryl trinitrate was reversed by coincubation with the guanylate cyclase inhibitor, methylene blue (10 microM). These findings indicate that glyceryl trinitrate, sodium nitroprusside and isosorbide dinitrate inhibit non-immunologically stimulated pulmonary histamine release and suggest that alterations in guanylate cyclase activity may influence pulmonary histamine release.