DOES THE SABRA HYPERTENSION-PRONE RAT REPRESENT A MODEL OF SALT OR MINERALOCORTICOID SENSITIVITY

Objectives Since the Sabra experimental model of hypertension was deve loped, it has been known as a model of salt-susceptible hypertension. Because the hypertensive response of the Sabra hypertension-prone stra in (SBH/y) is classically elicited by salt loading with a combination of deoxycorticosterone acetate (DOCA) and salt, doubt has now been cas t on whether the hypertensive response is due to sensitivity to salt o r to mineralocorticoids, The present study was designed to resolve thi s question, Materials and methods We studied the blood pressure respon se of SBH/y to various modes of salt loading. Animals were salt-loaded by administration of: 1% NaCl in drinking water and subcutaneous impl antation of a 25 mg DOCA pellet (DOCA-salt); DOCA alone; 1% NaCl in dr inking water alone; or 8% NaCl in chow alone, Blood pressure was deter mined by the tail-cuff method in awake and undisturbed animals. Result s Within 4 weeks, the DOCA-salt treatment elicited the full hypertensi ve response previously reported in the SBH/y strain. Salt loading with 8% NaCl in chow reproduced the full hypertensive response observed wi th DOCA-salt, except that it occurred only after 7 weeks of treatment. Salt loading with DOCA alone raised blood pressure moderately and to a maximal level within 3 weeks; the magnitude of the blood pressure re sponse was, however, significantly smaller than that observed with DOC A-salt or 8% NaCl in chow. Administration of 1% NaCl in water alone el icited no hypertensive response. Conclusions The hypertensive response to salt loading in the Sabra experimental model of hypertension is an expression primarily of salt sensitivity, as it can be fully reproduc ed with salt alone, but not with DOCA alone. The use of the DOCA-salt mode of salt loading in this model, as opposed to salt loading with 8% salt in chow, is a useful way of accelerating the development of salt -sensitive hypertension in SBH/y, which shortens, and therefore facili tates, phenotyping. (C) 1998 Lippincott Williams & Wilkins.