Angiotensin receptors: signaling, vascular pathophysiology, and interactions with ceramide. (review)

Berry, C., R. Touyz, A. F. Dominiczak, R. C. Webb, and D. G. Johns. Angiotensin receptors: signaling, vascular pathophysiology, and interactions with ceramide. Am J Physiol Heart Circ Physiol 281: H2337-H2365, 2001.--Angiotensin II (ANG II) is a pleiotropic vasoactive peptide that binds to two distinct receptors: the ANG II type 1 ([AT.sub.1]) and type 2 ([AT.sub.2]) receptors. Activation of the renin-angiotensin system (RAS) results in vascular hypertrophy, vasoconstriction, salt and water retention, and hypertension. These effects are mediated predominantly by [AT.sub.1] receptors. Paradoxically, other ANG II-mediated effects, including cell death, vasodilation, and natriuresis, are mediated by [AT.sub.2] receptor activation. Our understanding of ANG II signaling mechanisms remains incomplete. [AT.sub.1] receptor activation triggers a variety of intracellular systems, including tyrosine kinase-induced protein phosphorylation, production of arachidonic acid metabolites, alteration of reactive oxidant species activities, and fluxes in intracellular [Ca.sup.2+] concetrations. [AT.sub.2] receptor activation leads to stimulation of bradykinin, nitric oxide production, and prostaglandin metabolism, which are, in large part, opposite to the effects of the [AT.sub.1] receptor. The signaling pathways of ANG II receptor activation are a focus of intense investigative effort. We critically appraise the literature on the signaling mechanisms whereby [AT.sub.1] and [AT.sub.2] receptors elicit their respective actions. We also consider the recently reported interaction between ANG II and ceramide, a lipid second messenger that mediates cytokine receptor activation. Finally, we discuss the potential physiological cross talk that may be operative between the angiotensin receptor subtypes in relation to health and cardiovascular disease. This may be clinically relevant, inasmuch as inhibitors of the RAS are increasingly used in treatment of hypertension and coronary heart disease, where activation of the RAS is recognized. renin-angiotensin system; angiotensin receptor antagonist; second messenger Received 7 June 2000; accepted in final form 24 July 2001