Angiotensin II mesenteric and renal vasoregulation: Dissimilar modulatory effects with nitroprusside

• Published in: Acta anaesthesiologica Scandinavica Vol. 44; no. 10; pp. 1238 - 1245
• Main Authors: BroomÉ, M., Åneman, A., Haney, M., HÄggmark, S., Johansson, G., Biber, B.
• Format: Journal Article
• Language: English
• Published: Copenhagen Munksgaard International Publishers 01.11.2000; Blackwell
• Subjects: angiotensin amide; angiotensin II; Angiotensin II - blood; Angiotensin II - pharmacology; Angiotensin II/blood/pharmacology; Animals; atrial natriuretic factor; Biological and medical sciences; Blood Pressure - drug effects; Blood vessels and receptors; Female; Fundamental and applied biological sciences. Psychology; hemodynamics; Male; nitroprusside; Nitroprusside - pharmacology; pulmonary circulation; renal circulation; Renal Circulation - drug effects; Renin - blood; Renin-angiotensin system; splanchnic circulation; Splanchnic Circulation - drug effects; Swine; vasoconstriction; Vertebrates: cardiovascular system; Vasodilator agent; Lung; Vasoconstriction; Mesentery; Respiratory system; Kidney; Pig; Sodium nitroprusside; Vertebrata; Renin angiotensin system; Vasomotricity; Mammalia; Urinary system; Animal; Blood vessel; Vasoconstrictor agent; Circulatory system; Artiodactyla; Hemodynamics; Angiotensin II; Ungulata
• ISSN: 0001-5172; 1399-6576; 1399-6576
• DOI: 10.1034/j.1399-6576.2000.441009.x

Background: The role of systemic arterial pressure for the vascular effects of angiotensin II (Ang II) and the interactions between Ang II and perfusion pressure‐dependent local vascular control mechanisms are not well understood. This study addresses these aspects of exogenous Ang II in the mesenteric and renal regional circulations. Methods: Ang II was infused in incremental doses (0–200 μg/h) in anesthetized instrumented pigs (n=10). Renal and portal blood flows were measured by perivascular ultrasound. In the second part of the study, sodium nitroprusside (SNP) was infused at doses titrated to keep mean arterial pressure constant, in spite of concurrent Ang II administration. Results: Powerful dose‐dependent vasoconstrictions by Ang II were found in renal and mesenteric vascular beds (at highest Ang II doses vascular resistances increased by 109% and 88% respectively). Ang II‐induced vasoconstriction was fully inhibited in the mesenteric, but not in the renal circulation, during conditions of constant mean arterial pressures achieved by SNP infusion. Conclusions: Mesenteric, but not renal, vasoconstriction by Ang II was inhibited by pharmacological maintenance of perfusion pressure. This could reflect differences between these vascular beds as regards the importance of co‐acting myogenic pressure‐dependent vasoconstriction. Alternatively, as the drug chosen for pressure control, sodium nitroprusside, serves as a nitric oxide donor, the relative balance between nitric oxide‐mediated vasodilation and Ang II‐induced vasoconstriction could have regional differences.