Abstract
Adrenocorticotrophin (ACTH) produces adrenally dependent increases in both blood pressure and salt (NaCl) appetite in the rat. The present study examines the effect of free access to a high intake of NaCl on ACTH hypertension in the rat to test the hypothesis that high NaCl intake would amplify the rise in blood pressure. Either water or 1%NaCl were offered to sham or ACTH treated Sprague-Dawley rats. Subcutaneous injections of synthetic ACTH (0.5mg/kg/day) for 10 days caused large increases in the intake of both 1%NaCl (+240×6 ml/day) and water (+45×4 ml/day), urine volume (1%NaCl+ACTH +182×4 ml/day, ACTH+water +36×2ml/day), adrenal weight (ACTH+water 176×18, ACTH+1%NaCl 367×129mg/100g body weight) and maximum systolic blood pressure (SBP) (ACTH+water +18×5 mmHg; 1%NaCl+ACTH +16×3 mmHg). Some ACTH+1%NaCl rats developed severe edema. Thus, free access to NaCl in ACTH treated Sprague Dawley rats did not potentiate the hypertension, but was associated with edema in some animals.