Abstract 125: Modified Angiotensin II Has Lower Vasoconstrictive Effect Than Angiotensin II

Introduction: The renin-angiotensin-aldosterone system (RAAS) is involved in the regulation of the blood pressure, water- and electrolyte balance. Pathophysiologically, this system is essential for the development and pathogenesis of both cardiovascular and renal diseases. Angiotensin II, a component of the RAAS, is the best-known vasoconstrictive and hypertensive peptide in the human organism. This peptide consists of 8 amino acids (asp-arg-val-tyr-ile-his-pro-phe). The first amino acid, aspartic acid, is converted to pyruvamide in the presence of pyridoxal-5’-phosphate (PLP). The influence of pyruvamide-angiotensin II on the blood pressure is not yet clarified. Hypothesis: We assessed the hypothesis that the transformation of angiotensin II to pyruvamide-angiotensin II by PLP leads to lowering the blood pressure. Methods: To clarify the influence of pyruvamide-angiotensin II on blood pressure ex vivo experiments were performed. Angiotensin II as well as pyruvamide-angiotensin II was tested in isolated perfused rat kidney. Further, in vivo experiments were performed. Wistar Kyoto rats (WKY) and Spontaneously Hypertensive Rats (SHR) were treated with angiotensin II in the absence and presence of PLP. The blood pressure was measured at different time. Results: Pressure in isolated perfused rat kidney increases by 50.11 ± 4.57 mmHg after injecting angiotensin II, whereas pressure increases by 38.40 ± 4.31 mmHg after injecting pyruvamide-angiotensin II. Data are shown as mean ± SEM of triplicate measurements from three independent experiments. Further, blood pressure of SHR treated with PLP decreases from 171/139 ± 5 mmHg to 129/98 ± 2 mmHg after three days. Blood pressure of WKY treated with angiotensin II increases to 167/133 ± 3 mmHg, whereas blood pressure of WKY treated with angiotensin II and PLP decreases to 129/99 ± 2 mmHg. Data are shown as mean ± SEM from five independent experiments. Conclusions: In conclusion, pyruvamide-angiotensin II has a lower vasoconstrictive effect than angiotensin II. Furthermore, PLP decreases the blood pressure in SHR and WKY.