Carbon monoxide does not inhibit glyceryl trinitrate biotransformation by or relaxation of aorta

Carbon monoxide (CO) was employed to assess the role of ferrous hemoproteins in the vasodilation and biotransformation of glyceryl trinitrate (GTN) in rabbit aortic strips. These tissues were contracted submaximally with phenylephrine, exposed to CO for 5 min, and then incubated with 0.5 microM [1,3(14) C]GTN in the presence of CO for 2 min or 30 s. The [14C]GTN-induced relaxation of the strips was recorded, and [14C]GTN biotransformation to [14C]glyceryl dinitrate metabolites by the tissues was determined by thin-layer chromatographic-liquid scintillation spectrometric analysis. CO treatment inhibited neither GTN-induced relaxation nor GTN biotransformation to glycerol dinitrate metabolites. These results indicate that ferrous hemoproteins are probably not involved in the biotransformation of GTN that is associated with relaxation of the rabbit aortic strips.