ENDOTHELIN RECEPTOR HETEROGENEITY, G-PROTEINS, AND SIGNALING VIA CAMPAND CGMP CASCADES

1. The endothelins (ETs) are potent vasoactive peptides which are invo lved in diverse biological processes, such as contraction, neuromodula tion, and neurotransmission, as well as in certain pathophysiological conditions including cardiac and renal failure. 2. The diversity of ac tion of ETs may be attributed to (i) the existence of a number of rece ptor subtypes, and (ii) the G-protein-mediated activation of different signal transduction pathways. 3. The combined action of these two var iables modulates the response, since different receptor subtypes can s timulate and/or inhibit the cAMP and cGMP cascades.