Abstract
The urine of a normal dog when injected intravenously into another dog in doses of three cubic centimeters causes an immediate fall in blood pressure varying from 25 to 96 mm. of Hg. This effect, constant for normal urine, is not always obtained when the urine from a chromate or uranium nephritis of the third to fifth day is used. It is still obtained, however, in arsenic and cantharidin nephritis of the same periods. This difference suggests that in the tubular lesions of chromate and uranium nephritis, which are characterized by extensive epithelial destruction, some substance normally eliminated is retained while in the glomerular nephritis caused by arsenic and cantharidin poisoning this retention does not occur. The elimination of the depressor substance would appear therefore to be a function of the tubular epithelium.
In animals with experimental nephritis of the tubular type the disappearance of the depressor substance from the urine is frequently associated with a lowering of the blood pressure which would appear to indicate that the retained depressor substance has a definite effect on the general blood pressure. This observation is not based however on blood pressure determinations on the same animal before and after the development of nephritis but by contrasting the pressure in animals with tubular nephritis with that of normal animals and those with glomerular nephritis.
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