title: Effects of converting enzyme inhibitors on angiotensin and bradykinin peptides.
abstract: We examined the dose-related effects of angiotensin-converting enzyme inhibitors on circulating and tissue levels of angiotensin and bradykinin peptides by administering perindopril or lisinopril to rats in drinking water for 7 days. A reduction in the ratio of plasma angiotensin II (Ang II) to Ang I was seen for 0.006 mg/kg per day perindopril, with an increase in plasma renin and Ang I at 0.017 mg/kg per day. Plasma Ang II levels did not decrease until 1.4 mg/kg per day perindopril, at which dose plasma Ang I levels reached a plateau of an approximate 25-fold increase. The effects of perindopril on Ang II and Ang I levels in heart, lung, aorta, and brown adipose tissue were parallel to those observed for plasma. By contrast, renal Ang I levels did not increase, and renal Ang II levels decreased by 40% at 0.017 mg/kg per day, the same threshold seen for the increase in plasma renin. Perindopril increased circulating bradykinin-(1-9) levels approximately eightfold, with a threshold dose of 0.052 mg/kg per day, and increased bradykinin-(1-9) levels in kidney, heart, and lung in parallel with the changes observed for plasma. By contrast, aortic and brown adipose tissue bradykinin-(1-9) and bradykinin-(1-7) levels increased severalfold for perindopril doses as low as 0.006 mg/kg per day. Lisinopril also increased aortic bradykinin-(1-9) and bradykinin-(1-7) levels at doses below the threshold for the decrease in the ratio of Ang II to Ang I. These data indicate that renal Ang II levels and vascular bradykinin-(1-9) levels respond to low doses of converting enzyme inhibitor and may be important mediators of the effects of these compounds. The parallel increases in bradykinin-(1-9) and bradykinin-(1-7) levels in aorta and brown adipose tissue, at inhibitor doses below the threshold for inhibition of Ang I conversion, may result from a mechanism different from inhibition of "classic" angiotensin-converting enzyme.
authors.affiliation: St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
authors.forename: D J
authors.initials: DJ
authors.lastname: Campbell
authors.forename: A
authors.initials: A
authors.lastname: Kladis
authors.forename: A M
authors.initials: AM
authors.lastname: Duncan
mesh_terms: D002001:Adipose Tissue, Brown / Q000737:chemistry; D000804:Angiotensin II / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000097:blood; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000808:Angiotensinogen / Q000097:blood; D000818:Animals; D001011:Aorta / Q000737:chemistry; D001920:Bradykinin / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000097:blood; D007211:Indoles / Q000494:pharmacology*; D007668:Kidney / Q000737:chemistry; D017706:Lisinopril / Q000494:pharmacology*; D008168:Lung / Q000737:chemistry; D008297:Male; D009206:Myocardium / Q000737:chemistry; D010446:Peptide Fragments / Q000032:analysis / Q000037:antagonists & inhibitors; D007703:Peptidyl-Dipeptidase A / Q000097:blood; D020913:Perindopril; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000097:blood
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007211:Indoles; D010446:Peptide Fragments; D000808:Angiotensinogen; D000804:Angiotensin II; D017706:Lisinopril; D007703:Peptidyl-Dipeptidase A; D012083:Renin; D001920:Bradykinin; D020913:Perindopril