Comparative effects of contraction and angiotensin ii on growth of adult feline cardiocytes in primary culture. Wada, Hisayasu, Michael R. Zile, Charles T. Ivester, George Cooper Iv, Paul J. McDermott. Departments of Medicine, Physiology, and Cell Biology and Anatomy, Gazes Cardiac Research Institute, and Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston SC. This study was supported by grant PO1 HL-48788 (GC, IV, MRZ, PJM) and by research funds from the Department of Veterans Affairs (GC, IV, MRZ, PJM)
APStracts 2:0498H, 1995.
The purposes of this study were: 1) to determine whether angiotensin II causes growth of adult feline cardiocytes in long-term culture, 2) compare the growth effects of angiotensin II with that resulting from electrically stimulated contraction, and 3) determine whether the anabolic effects of contraction are exerted via the angiotensin type 1 receptor. Adult feline cardiocytes were cultured on laminin-coated trays in a serum-free medium. Cardiocytes were either electrically stimulated to contract (1 Hz, 5 ms pulse duration, alternating polarity) or were non-stimulated and quiescent. Quiescent cells were studied as controls and following treatment with angiotensin II (10-8 M), losartan (10-6 M, an angiotensin type 1 receptor antagonist), or angiotensin II plus losartan. Contracting cells were studied in the presence and absence of angiotensin II, or losartan. In quiescent cardiocytes, angiotensin II treatment on day 7 significantly increased protein synthesis rates by 22% and protein content per cell by 17%. The effects of angiotensin II were completely blocked by losartan. Electrically stimulated contraction on day 4 and 7 in culture significantly increased protein synthesis rate by 18% and 38% and protein content per cell by 19% and 46%, respectively. Angiotensin II treatment did not further increase protein synthesis rate or protein content in contracting cardiocytes. Furthermore, losartan did not block the anabolic effects of contraction on protein synthesis rates or protein content. In conclusion, angiotensin II can exert a modest anabolic effect on adult feline cardiocytes in culture. In contracting feline cardiocytes, angiotensin II has no effect on growth. Growth caused by electrically stimulated contraction occurs more rapidly and is greater in magnitude than that caused by angiotensin II. Growth of contracting adult feline cardiocytes is not dependent upon activation of the angiotensin receptor. 

Received 6 July 1995; accepted in final form 24 October 1995.
APS Manuscript Number H620-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95