Transgenic mouse models of angiotensin receptor subtype function in the cardiovascular system

Angiotensin II mediates is biological actions via different subtypes of G p rotein-coupled receptors, termed AT(1) and AT(2) receptors. In rodents, two AT(1) receptors have been identified, AT(1A) and AT(1B), whereas in humans a single AT(1) receptor exists. Recently, a number of transgenic animal mo dels have been generated which overexpress or lack functional angiotensin I I receptor subtypes. This review focuses on the physiological significance of angiotensin II receptor subtype diversity in the cardiovascular system. In the mouse, AT(1A) receptors are the major regulators of cardiovascular h omeostasis by determining vascular tone and natriuresis. In addition, AT(1A ) receptors mediate growth-stimulating signals in vascular and cardiac myoc ytes. AT(1B) receptors participate in blood pressure regulation, and their functions become apparent when the AT(1A) receptor gene is deleted. Deletio n of the mouse gene for the AT(2) receptor subtype led to hypersensitivity to presser and antinatriuretic effects of angiotensin II in vivo, suggestin g that the AT(2) receptor subtype counteracts some of the biological effect s of AT(1) receptor signalling. (C) 2001 Elsevier Science B.V. All rights r eserved.