Experimental Production of Renal and Vascular Lesions with Metaraminol

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IN the course of experiments in which hypertension was produced by subcutaneous injections of metaraminol, a drug with sustained pressor and vasoconstrictor effects,1 we noticed lesions of renal necrosis. These pathologic changes were investigated, and they are the subject of this paper in which we also discuss their inhibition by hydralazine.

Experimental Study

1. Effects of metaraminol in normal (control) rats. In acute experiments, Sprague-Dawley rats that weighed from 250 to 300 gm. were each attached on a board while under sodium amytal anesthesia (dosage: 9 mg. per 100 gm. of body weight). Metaraminol was injected subcutaneously in a single dose of 1 or 2 mg. and the kidneys were examined through an incision in the abdominal wall. After ten minutes, the fur became ruffled and wet, the eyes protruded, and frothy fluid appeared around the mouth and nose. The kidneys were mottled by alternate areas of congestion and ischemia (Fig. 1).

In chronic experiments, metaraminol was given subcutaneously in three daily injections of 0.5 mg. each. The injected rats as well as some untreated control animals were placed in metabolism cages. The same but less severe symptoms as described above occurred after each injection and lasted for about one-half hour. Body weight decreased sharply during the first 24 hours, averaging 195 gm. as compared with an initial value of 222 gm. Then body weight remained stable in some animals, while in others it recovered some of its loss. At the end of the experiment, body weight averaged 218 gm.. . .



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