THE EFFECT OF MONOAMINE OXIDASE INHIBITORS UPON URINARY EXCRETION OF DOPAMINE AND CHANGES IN ARTERIAL BLOOD PRESSURE
The relationship between urinary dopamine levels, and arterial blood pressure was studied in male albino rats. The experimental rats were subjected to a right nephrectomy and received a monoamine oxidase inhibitor, either tranylcypromine or pargyline. The blood pressure of the group receiving tranylcypromine was elevated to approximately 120 mm Hg during the first two weeks. During weeks seven and eight the blood pressure was further elevated to approximately 130 mm Hg but dropped back gradually to 115 mm Hg for a net drop of 3 percent where it remained to the end of the study. The blood pressure of the pargyline group, as expected, dropped steadily from approximately 115 mm Hg to approximately 84 mm Hg for a net drop of 34 percent. Dopamine was extracted from paired urine samples by alumina and measured by spectrophotofluorimetry. Dopamine levels (mean from paired urine samples) of the experimental animals receiving pargyline or tranylcypromine were approximately 6 ug/ml/24 hour urine sample and 5 ug/ml/24 hour urine sample. These were lower than the levels of the control groups.