The involvement of the renin-angiotensin system in regulation of cardiovas cular and renal function during health and disease remains under intense investigation. New and exciting developments have emerged in angiotensin receptor subtypes, signal transduction mechanisms, modulators such as GTP binding and regulatory proteins (G proteins), as well as multiple protein kinases and phosphatases. Developments in the receptor field have been facilitated by the discovery of a new class of selective angiotensin II (All) receptor antagonists, the nonpeptide selective, imidazole derivatives origi nally reported by Furukawa et al (25). These compounds distinguish separate classes of AIl receptors; some have the important property of being potent antihypertensive agents (AT 1 antagonists), while others define a class of receptors for AIl that do not seem to be directly involved in blood pressure control (AT: z). This latter group appears to modulate potassium permeability and guanyl cyclase through protein tyrosine phosphorylation in neuronal