Long-term angiotensin-converting enzyme inhibition with fosinopril improves depressed responsiveness to Ca2+ in myocytes from aortic-banded rats

• Published in: Circulation (New York, N.Y.) N.Y.), 1996-12, Vol.94 (11), p.2915-2922
• Main Authors: KAGAYA, Y, HAJJAR, R. J, GWATHMEY, J. K, BARRY, W. H, LORELL, B. H
• Format: Article
• Language: English
• Subjects: Angiotensin-Converting Enzyme Inhibitors - pharmacology; Animals; Aorta; Biological and medical sciences; Calcium - pharmacology; Cardiac Output, Low - prevention & control; Cardiomegaly - pathology; Cardiomegaly - physiopathology; Cardiovascular system; Constriction; Fosinopril - pharmacology; Heart - drug effects; Hypertension - pathology; Hypertension - physiopathology; Male; Medical sciences; Myocardial Contraction - drug effects; Myocardium - pathology; Pharmacology. Drug treatments; Rats; Rats, Wistar; Time Factors; Vasodilator agents. Cerebral vasodilators
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.94.11.2915

We have previously shown that long-term ACE inhibition with fosinopril prolongs survival and improves ventricular function despite persistent severe left ventricular pressure overload in ascending aortic-banded rats with left ventricular hypertrophy during the transition from compensation to failure. To study the cellular mechanism of the effects of long-term ACE inhibition on the modification of the transition to failure in pressure-overload hypertrophy, we measured simultaneous intracellular Ca2+ transients and myocyte shortening in isolated left ventricular myocytes from fosinopril-treated aortic-banded rats (n = 9), untreated aortic-banded rats (n = 9), and normal age-matched control rats (n = 10). Fosinopril therapy was begun 6 weeks after banding and was continued until week 21 after banding, when the animals were killed. Collagenase-dissociated myocytes loaded with indo 1-AM were paced at 3 Hz at 36 degrees C and superfused at [Ca2+]o of 0.6, 1.2, and 3.0 mmol/L. In myocytes from untreated aortic-banded rats, peak systolic [Ca2+]i was higher than in control myocytes, and the relationship between myocyte shortening and [Ca2+]i was depressed relative to control myocytes, implicating impaired responsiveness to Ca2+. Long-term fosinopril treatment improved both myocyte shortening and the relationship of shortening to [Ca2+]i (P < .05 versus myocytes from untreated aortic-banded rats). Maximal Ca(2+)-activated force was depressed in chemically skinned left ventricular fibers from untreated aortic-banded hypertrophied rats relative to age-matched controls but not in the fosinopril-treated aortic-banded rats. Long-term ACE inhibition improves responsiveness to Ca2+ in the presence of normalization of maximal Ca(2+)-activated force in aortic-banded rats subjected to persistent pressure overload. This may contribute to the favorable effects whereby ACE inhibition modifies the transition from compensated hypertrophy to failure.