Drug Discovery for Overcoming Chronic Kidney Disease (CKD): The Endothelin ETB Receptor / Nitric Oxide System Functions as a Protective Factor in CKD

Abstract

Accelerated cardiovascular disease (CVD) is a frequent complication of renal disease. Chronic kidney disease (CKD) develops hypertension and dyslipidemia, which in turn can contribute to the progression of renal failure. There is general agreement that endothelin-1 (ET-1), which acts through the two subtypes of receptor ETA and ETB, plays important physiological roles in the regulation of normal cardiovascular function and that excessive ET-1 production is linked to CVD and CKD. Although selective ETA or nonselective ETA/ETB receptor antagonisms have been recognized as a potential strategy for treatment of several cardiovascular disease, it remains unclear which of the antagonisms is suitable for the individuals with CKD because upregulation of the nitric oxide (NO) system via ETB receptor is responsible for renal function such as natriuresis, diuresis, and glomerular hemodynamics. Our findings clearly indicate that the blockade of ET receptors, in particular ETA-receptor antagonism, not only produces a potential renoprotective effect in CKD but also reduces the risk of CVD. In contrast, pharmacological blockade or genetic deficiency of ETB receptor seems to aggravate CKD and CVD in several experimental models of rats. Moreover, preliminary evidence in patients with CKD also suggests that both selective ETA- and nonselective ETA/ETB-receptor blockade decreases blood pressure but that selective ETA blockade has additional desirable effects on renal hemodynamics. Thus, at least in CKD, these findings support the notion that ETB receptor– mediated actions produce a renoprotective effect and that nonselective ETA/ETB-receptors blockade seem to offer no advantage over selective ETA antagonism, and if anything may potentially reduce the benefits. Keywords:: endothelin-1 (ET-1), ETB receptor, chronic kidney disease (CKD), nitric oxide (NO), nitric oxide synthase