Rats with adenine-induced chronic renal failure (A-CRF) develop metabolic and cardiovascular abnormalities resembling those in patients with chronic kidney disease. The aim of this study was to investigate the mechanisms of hypertension in this model and to assess aortic stiffness in vivo. Male Sprague-Dawley rats were equipped with radiotelemetry probes for arterial pressure recordings and received either chow containing adenine or normal control diet. At 7 to 11 wk after study start, blood pressure responses to high NaCl (4%) diet and different pharmacological interventions were analyzed. Aortic pulse wave velocity was measured under isoflurane anesthesia. Baseline 24-h mean arterial pressure (MAP) was 101 ± 10 and 119 ± 9 mmHg in controls and A-CRF animals, respectively (P < 0.01). After 5 days of a high-NaCl diet, MAP had increased by 24 ± 6 mmHg in A-CRF animals vs. 2 ± 1 mmHg in controls (P < 0.001). Candesartan (10 mg/kg by gavage) produced a more pronounced reduction of MAP in controls vs. A-CRF animals (-12 ± 3 vs. -5 ± 5 mmHg, P < 0.05). Aortic pulse wave velocity was elevated in A-CRF rats (5.10 ± 0.51 vs. 4.58 ± 0.17 m/s, P < 0.05). Plasma levels of creatinine were markedly elevated in A-CRF animals (259 ± 46 vs. 31 ± 2 μM, P < 0.001), whereas plasma renin activity was suppressed (0.6 ± 0.5 vs. 12.3 ± 7.3 μg·l(-1)·h(-1), P < 0.001). In conclusion, hypertension in A-CRF animals is characterized by low plasma renin activity and is aggravated by high-NaCl diet, suggesting a pathogenic role for sodium retention and hypervolemia probably secondary to renal insufficiency. Additionally, aortic stiffness was elevated in A-CRF animals as indicated by increased aortic pulse wave velocity.
Keywords: adenine; aortic stiffness; chronic kidney disease; hypertension; pulse wave velocity.