AREGU Mar. 45/3

Oyekan, A. O., K. McAward, J. Conetta, L. Rosenfeld, and John C. McGiff. Endothelin-1 and CYP450 arachidonate metabolites interact to promote tissue injury in DOCAsalt hypertension. Am. J. Physiol. 276 (Regulatory Integrative Comp. Physiol. 45): R766–R775, 1999.—Inhibition of cytochrome P-450 (CYP450) enzymes with cobalt chloride (CoCl2) prevented hypertension, organ hypertrophy, and renal injury induced by DOCA and salt (1% NaCl) in uninephrectomized (UNx) rats. Systolic blood pressure (SBP) rose to 193 6 6 mmHg by day 21 from control levels of 150 6 7 mmHg in response to DOCA-salt treatment, a rise that was prevented by CoCl2 (24 mg·kg21 ·24 h21). The effects of DOCA-salt treatment, which increased protein excretion to 88.3 6 6.9 mg/24 h on day 21 from 9.0 6 1.1 mg/24 h on day 3, were prevented by CoCl2. CoCl2 also attenuated the renal and left ventricular hypertrophy and the increase in media-to-lumen ratio in hypertensive rats. DOCA-salt treatment increased excretion of endothelin (ET)-1 from 81 6 17 to 277 6 104 pg·100 g body wt21 ·24 h21 associated with a fourfold increase in 20-hydroxyeicosatetraenoic acid (20-HETE) excretion from 3.0 6 1.1 to 12.2 6 1.9 ng·100 g body wt21 ·24 h21 (days 3 vs. 21). CoCl2 blunted these increases by 58 and 72%, respectively. In aortic rings pulsed with [3H]thymidine, ET-1 increased its incorporation. Dibromododec-11-enoic acid, an inhibitor of 20-HETE synthesis, attenuated ET-1-induced increases in [3H]thymidine incorporation. We distinguished effects of CoCl2 acting via CO generation vs. suppression of CYP450-arachidonic acid metabolism by treating UNx-saltDOCA rats with 1-aminobenzotriazole (ABT), which suppresses CYP450 enzyme activity, and compared these results to those produced by CoCl2. ABT reduced hypertension, as did CoCl2. Unlike CoCl2, ABT did not prevent organ hypertrophy and proteinuria, suggesting that these effects were partially related to CO formation. Blockade of the ETA receptor with BMS-182874 reduced SBP, organ hypertrophy, and proteinuria, indicating the importance of ET-initiated abnormalities to the progression of lesions in UNx-salt-DOCA.