The dynamics of hypothalamic arginine vasopressin (AVP) release was examined during the development of hypertension in rats with deoxycorticosterone (DOCA)-NaCL induced hypertension. Experiments were performed in four groups of uninephrectomized Sprague-Dawley rats 3, 7, 14 and 21 days after treatment with: (I) DOCA and 1% saline (DOCA-NaCl); (II) DOCA, regular chow, and tap water (DOCA-R-H2O); (III) regular chow and 1% saline (NaCl); and (IV) regular chow and tap water (H2O). Systolic blood pressure (BP) was significantly elevated in DOCA-NaCl and DOCA-R-H2O (183 +/- 5 and 155 +/- 4 mm Hg, respectively) but not in an additional control group which received DOCA and a low NaCl diet (119 +/- 2 mm Hg). Plasma AVP and hypothalamic AVP release were increased in all DOCA treated groups at each time point studied, while plasma osmolality was similar in each group. These studies demonstrate increases in the hypothalamic release of AVP in DOCA-NaCl hypertensive animals, but suggest that they are due to the mineralocorticoid and are independent of blood pressure and NaCl intake.