Effects of AT1 and AT2 Angiotensin Receptor Antagonists in Angiotensin II-Infused Rats

Abstract

Angiotensin II (Ang II) appears to exert its contractile and growth-promoting effects through the AT1 receptor subtype, whereas the AT2 subtype may have growth-inhibitory and proapoptotic properties. Recently, some data have challenged this emerging concept. To clarify the role of AT1 and AT2 receptors, we treated Wistar rats that were infused with Ang II (120 ng/kg/min subcutaneously by osmotic minipump), with the AT1 antagonist losartan (10 mg/kg/d in the drinking water) and the AT2 antagonist PD123319 (30 mg/kg/d subcutaneously by osmotic minipump) for 21 days. At the end of the study, tail-cuff systolic blood pressure was 106 +/- 2.8 mm Hg in untreated rats and 108 +/- 2.0 mm Hg in rats infused with Ang II that received losartan, whereas it rose to 158 +/- 4.9 mm Hg in Ang II-infused rats and 158 +/- 3.0 mm Hg in rats infused with Ang II rats and PD123319 (the two latter groups P