ROLE OF ANGIOTENSIN (1-7) ON CARDIOVASCULAR STRUCTURE AND FUNCTION IN AGED SPONTANEOUSLY HYPERTENSIVE RATS

摘要

Background: The heptapeptide, Ang (1-7), has been shown to possess actions opposing that of Ang II, as Ang (1-7) reversed endothelial dysfunction and cardiac remodelling following myocardial infarction, and also caused a depressor response in adult spontaneously hypertensive rats (SHR).Aims: Therefore the aims of this study were to examine the effects of chronic (4 weeks) Ang (1-7) treatment (24 ng/kg/hour via osmotic mini-pump) either alone, or in the presence of the AT_1 (candesartan cilexetil (Cand), 2 mg/kg/day via drinking water) or AT_2 (PD 123319, 10 mg/kg/day via osmotic mini pump) receptor antagonists, on cardiovascular structure and function in aged SHR (18-20 months). Methods: Mean arterial pressure (MAP) and heart rate were monitored continuously throughout the treatment period via radio-telemetry. At the end of the study, media: lumen ratio (MLR) and superoxide production (detected by lucigenin-enhanced chemilumi-nescence) were determined in thoracic aortae. Ventricular: body weight ratio was also determined as an indicator of cardiac hypertrophy, and hearts were processed and stained with 0.001% Picrosirius red for analysis of cardiac fibrosis.