Simultaneous administration of Ang(1-7) or A-779 does not affect the chronic hypertensive effects of angiotensin II in normal rats

HYPOTHESIS: The following studies were designed to test the hypothesis that simultaneous administration of either Ang(1-7) or its antagonist A-779 would affect the chronic hypertensive effects of angiotensin II (Ang II). INTRODUCTION: Despite the well-described actions of Ang(1-7) and its role possessing opposite actions to Ang II, there have been few studies examining the role of Ang(1-7) in a chronic setting. It is well established that Ang(1-7) plays a protective role in preventing deleterious effects of Ang II in the heart, but little is known of its role in modulating the chronic hypertensive effects of Ang II. MATERIALS AND METHODS: Rats were instrumented with venous catheters and telemetric pressure transducers. Arterial pressure responses were measured in rats treated with Ang II (10 ng/kg/ min) (n=9) and compared with those treated with Ang II and Ang(1-7) (24 microg/kg/h) (n=8), or the Ang(1-7) antagonist A-779 (24 microg/kg/h) (n=7) for 8 days. RESULTS: Mean arterial pressure rose significantly and similarly in all three groups of rats, such that by day 8 of Ang II infusion, pressures had risen 25-30 mmHg in all rats. CONCLUSIONS: These results do not support the hypothesis that the chronic hypertensive effects of Ang II in normal rats are altered by co-administration of either Ang(1-7) or A-779.