High sodium intake blunts the efficacy of angiotensin (Ang)-converting enzyme (ACE) inhibition (ACEi), but the underlying mechanism is incompletely characterized. High sodium has been reported to increase vascular expression and vascular activity of ACE. To investigate whether high-dietary sodium-induced effects on vascular conversion of Ang I might be involved in the sodium-induced blunting of the response to ACEi, the authors studied the vasoconstrictor responses to Ang I and Ang II of isolated aortic rings from healthy rats on low dietary sodium (LS: 0.05% NaCl) and high dietary sodium (HS: 2.0% NaCl) after 3 weeks of ACEi (lisinopril 75 mg/L) or vehicle (CON). Blood pressure was similar in LS and HS in CON, but HS blunted the blood pressure response to ACEi. Functional conversion of Ang I was assessed as the difference in dose-response curves to Ang I and Ang II in parallel aortic rings. Sodium intake did not affect the dose-response curves to Ang I and Ang II in CON. In the ACEi groups, a significant difference was present between the curves for Ang I and Ang II on LS (ΔEC50, 6.7 nM; range, 2.2-13 nM; P < 0.01) but not on HS (ΔEC50: 1.3 nM; range, 0.0-4.1 nM, median [interquartile range], NS). Thus, HS blunts the ACEi-induced reduction of functional vascular Ang I conversion compared with LS. Whether the blunted functional vascular conversion is causally related to the blunted blood pressure response remains to be elucidated.

Angiotensin-converting enzyme inhibitor, Aorta, Dietary sodium, Rat, Vascular angiotensin I conversion
dx.doi.org/10.1097/00005344-200311000-00004, hdl.handle.net/1765/66189
Journal of Cardiovascular Pharmacology
Department of Internal Medicine

Kocks, M.J.A, Buikema, H.J, Gschwend, S, Boomsma, F, de Zeeuw, D, & Navis, G. (2003). High Dietary Sodium Blunts Effects of Angiotensin-converting Enzyme Inhibition on Vascular Angiotensin I-to-Angiotensin II Conversion in Rats. Journal of Cardiovascular Pharmacology, 42(5), 601–606. doi:10.1097/00005344-200311000-00004