6533b826fe1ef96bd1284666

RESEARCH PRODUCT

PO-002 Angiotensin II-induced hypertension increases the mutation frequency in the rat kidney

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Introduction Epidemiological studies revealed an increased risk for kidney cancer in hypertensive patients. In many of these patients, the blood pressure regulating renin angiotensin aldosterone system (RAAS) is activated. A stimulated RAAS can lead to oxidative stress and DNA damage, as we have shown both in vitro and in animal models of hypertension. Here, we used a rat model to quantify mutations generated by 20 weeks of angiotensin II-infusion. Material and methods BigBlue+/- rats, which carry a transgenic lacI gene for mutation analysis, were treated with 0.4 mg angiotensin II/kg/day with the help of osmotic minipumps. Urinary samples were collected in week 15 by placing the rats into metabolic cages. After 20 weeks of treatment the kidneys were isolated and analysed for oxidative stress markers, DNA damage and mutation frequency. Results and discussions Angiotensin II-treated animals showed significantly increased levels of blood pressure. Urinary and blood parameters of oxidative stress to proteins and nucleobases were increased. Lipoxygenation products were reduced in urine compared to the control animals, pointing to impaired renal excretion of these substances. Oxidative stress and the surrogate marker for DNA double-strand breaks, γ-H2AX, was significantly increased in the renal cortex. Further, a significant elevation of the mutation frequency in kidney DNA was detected. Sequencing results revealed the presence of G->T transversions in the mutated reporter gene of the angiotensin II-treated animals while no such transversions were found in the mutated reporter gene from the control animals. G->T transversions are mutations arising typically from the unrepaired oxidised base modification 8-oxodG. Conclusion This study shows evidence that the oxidative stress and DNA damage previously observed in vitro and in animal models of hypertension after angiotensin II treatment is indeed associated with the formation of mutations in rat kidneys, providing further evidence for a cancer initiating potential of increased angiotensin II concentrations.