Different angiotensin II-forming pathways in human and rat vascular tissues.
We studied the angiotensin II-forming pathways in extracts from human and rat vascular tissues. In the extract from human artery, angiotensin I mainly converted to two products, angiotensin-(1-9) and angiotensin II, while in the extract from rat artery, the major angiotensin I products were angiotensin II and angiotensin-(5-10). The concentrations of angiotensin II and angiotensin-(1-9) generated in the human extract (1 mg protein/ml) after incubation for 30 min were 3.2 and 2.5 nmol, respectively, and that of angiotensin II and angiotensin-(5-10) generated in the rat extract (1 mg protein/ml) were 0.28 and 2.3 nmol, respectively. In the extract from human vascular tissues, the angiotensin II formation was inhibited by 8% with lisinopril and by 95% with chymostatin. The other product, angiotensin-(1-9) was inhibited completely by carboxypeptidase inhibitor. In the extract from rat vascular tissues, the angiotensin II formation was suppressed to 4% by lisinopril, but not by chymostatin. The angiotensin-(5-10) formation was completely inhibited by chymostatin. These findings suggest clearly that human vascular tissues contain two angiotensin II-forming enzymes, angiotensin-converting enzyme and chymase, but rat vascular tissues have no chymase-dependent angiotensin II-forming pathway.
Takai
S
S
Department of Pharmacology, Osaka Medical College, Takatsuki City, 569-8686, Osaka, Japan. pha010@art.osaka-med.ac.jp
Sakaguchi
M
M
Jin
D
D
Yamada
M
M
Kirimura
K
K
Miyazaki
M
M
D000328:Adult; D000804:Angiotensin II / Q000096:biosynthesis*; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D051381:Rats; D017207:Rats, Sprague-Dawley
D004791:Enzyme Inhibitors; D000804:Angiotensin II