Exaggerated Vascular and Renal Pathology in Endothelin-B Receptor–Deficient Rats With Deoxycorticosterone Acetate–Salt Hypertension

Abstract

Background —Endothelin (ET)-1 plays an important role in the pathogenesis of deoxycorticosterone acetate (DOCA)-salt–induced hypertension. We evaluated the pathological role of ET B receptors in DOCA-salt–induced hypertension, cardiovascular hypertrophy, and renal damage by using the spotting-lethal ( sl ) rat, which carries a naturally occurring deletion in the ET B receptor gene. Methods and Results —Homozygous ( sl / sl ) rats exhibit abnormal development of neural crest–derived epidermal melanocytes and the enteric nervous system, and they do not live beyond 1 month because of intestinal aganglionosis and intestinal obstruction. The dopamine β-hydroxylase (DβH) promoter was used to direct ET B transgene expression in sl / sl rats to support normal enteric nervous system development. DβH-ET B sl/sl rats live into adulthood and are healthy, expressing ET B receptors in adrenal glands and other adrenergic neurons. When homozygous ( sl / sl ) and wild-type (+/+) rats, all of which were transgenic, were treated with DOCA-salt, homozygous rats exhibited earlier and higher increases in systolic blood pressure than did wild-type rats. Chronic treatment with ABT-627, an ET A receptor antagonist, completely suppressed DOCA-salt–induced hypertension in both groups. Renal dysfunction and histological damage were more severe in homozygous than in wild-type rats. Marked vascular hypertrophy was observed in homozygous rats than in wild-type rats. Renal and vascular injuries were significantly improved by ABT-627. In DOCA-salt–treated homozygous rats, there were notable increases in renal, urinary, and aortic ET-1, all of which were normalized by ABT-627. Conclusions —ET B -mediated actions are protective in the pathogenesis of DOCA-salt–induced hypertension. Enhanced ET-1 production and ET A -mediated actions are responsible for the increased susceptibility to DOCA-salt hypertension and tissue injuries in ET B receptor–deficient rats.