The effect of chronic ACTH treatment on blood pressure and urinary excretion of steroids in the rat.

The effects of subcutaneous injections of synthetic ACTH during 14 subsequent days has been studied in the rat. ACTH caused a loss in body weight which was related to a negative water balance. Blood pressure rose rapidly and reached values higher than 180 mm Hg in all rats after 10 days of ACTH administration. During this period, urinary excretion of corticosterone and 18-hydroxy-deoxycorticosterone (18-OH-DOC) was increased more than ten times, while aldosterone excretion was increased only during the first two days. After withdrawal of ACTH, excretion of steroids normalized, or in some cases was even suppressed and water balance and body weight gain returned to normal values. However, blood pressure remained slightly higher than in controls after ten days. The effects of ACTH on water balance and blood pressure resemble those of corticosterone in the rat. The rapidly induced and sustained changes in blood pressure by ACTH administration suggest that this may be an useful model of experimental hypertension.