Endothelin receptor heterogeneity, G-proteins, and signaling via cAMP and cGMP cascades

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