ENDOTHELINS - RENAL TUBULE SYNTHESIS AND ACTIONS

1. Renal tubules and, in particular, the inner medullary collecting du ct, produce endothelin and express cognate receptors. 2. Endothelins i nhibit vasopressin-stimulated cAMP accumulation and water reabsorption in the collecting duct; endothelins may also inhibit sodium reabsorpt ion in the proximal tubule and collecting duct. 3. Autocrine inhibitio n of sodium and water reabsorption in the inner medullary collecting d uct by endothelin may play a role in maintaining extracellular fluid v olume homeostasis. 4. Derangements in autocrine inhibition of sodium a nd water reabsorption in the inner medullary collecting duct by endoth elin may be involved in the pathogenesis of the hypertensive state. 5. Nephron-derived endothelins may function in a paracrine manner to reg ulate interstitial, juxtaglomerular and vascular smooth muscle cell fu nction.