The effects of l-norepinephrine on myocardial zonal lesions in dogs in hemorrhagic shock.

Intravenous l-norepinephrine was given to dogs in hemorrhagic shock to determine the effect on myocardial zonal lesions which are characteristically seen in hypovolemic shock. Zonal lesions produced by hemorrhagic shock in drug-treated and nondrug-treated groups were quantitatively compared both at the light microscopic and ultrastructural levels. A significantly greater percentage of myocardium was found to be involved with zonal lesions in animals treated with l-norepinephrine following shock as compared to that found in nondrug-treated animals. The effect was greater for the right ventricle than for the left ventricle. The average size of zonal lesions was slightly smaller in the drug-treated group, indicating that there must have been a greater total number of zonal lesions produced in the treated group. Zonal lesions were not present in "sham shock" animals nor in animals given l-norepinephrine alone. The results indicate that the treatment of hemorrhagic shock with l-norepinephrine can be anatomically deleterious to the heart.