Evaluation of the renin-angiotensin system in cardiac tissues of cats with pressure-overload cardiac hypertrophy.
OBJECTIVE
To clarify regulation of the renin-angiotensin (RA) system in cardiac tissues by measuring angiotensin-converting enzyme (ACE) and chymase activities in cats with pressure-overload cardiac hypertrophy.


METHODS
13 adult cats.


METHODS
Pressure-overload cardiac hypertrophy was induced by coarctation of the base of the ascending aorta in 6 cats, and 7 cats served as untreated control animals. Cats were examined before and 3 months and 2 years after surgery. Two years after surgery, cardiac hypertrophy was confirmed by echocardiography, and the blood pressure gradient was measured at the site of constriction. Cats were euthanized, and ACE and chymase activities were measured in cardiac tissues.


RESULTS
Mean +/- SD pressure gradient across the aortic constriction was 63 +/- 6 mm Hg. Chymase activity predominated (75% to 85%) in the RA system of the cardiac tissues of cats. Fibrosis in the wall of the left ventricle was detected in cats with hypertrophy, and fibrosis of the papillary muscle was particularly evident.


CONCLUSIONS
Chronic pressure overload on the heart of cats can activate the RA system in cardiac tissues. A local increase in angiotensin II was one of the factors that sustained myocardial remodeling.
Uechi
Masami
M
Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-8510, Japan.
Tanaka
Yoshiyuki
Y
Aramaki
Yoshitaka
Y
Hori
Yasutomo
Y
Ishikawa
Yumi
Y
Ebisawa
Takashi
T
Yamano
Shigeki
S
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002371:Cat Diseases / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology*; D002415:Cats; D053818:Chymases / Q000378:metabolism; D004452:Echocardiography / Q000662:veterinary; D006651:Histocytochemistry / Q000662:veterinary; D017379:Hypertrophy, Left Ventricular / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology*
D007703:Peptidyl-Dipeptidase A; D053818:Chymases