Abstract：
:Active tension developed while cardiac muscle shortens has been studied extensively under afterloaded isotonic or isovelocity conditions. However, these are not true in vivo loading conditions. To obtain more physiological loading, we controlled sarcomere length to follow the time courses that we observed previously in a beating canine left ventricle. Sarcomere length was measured by laser diffraction in 12 rat cardiac trabeculae, superfused with Krebs-Henseleit solution (25 degrees C; [Ca] = 1.5 mM). Force was measured by a silicon strain gauge. Sarcomere length time courses were scaled slightly in time to account for temperature and species differences. We examined the relationships between active tension and sarcomere length under loading observed over a wide range of left ventricular preloads and afterloads, and at two sites. Under all loading conditions, active tension was not isotonic but declined steadily throughout the ejection period. While there were major differences in peak tension dependent on loading conditions and the incidence of 'pre-ejection' sarcomere shortening, these factors did not influence the relationship between sarcomere length and peak active tension. This study provides excellent illustrations of the potential differences in stress (1) within a ventricular wall, and (2) under different operating conditions. Moreover, it provides data for developing models of fiber contraction to be synthesized into a whole heart for predicting potential differences in stress at all sites and under all loading conditions.
journal_name
J Biomechjournal_title
Journal of biomechanicsauthors
Guccione JM,Le Prell GS,de Tombe PP,Hunter WCdoi
10.1016/s0021-9290(96)00122-4subject
Has Abstractpub_date
1997-02-01 00:00:00pages
189-92issue
2eissn
0021-9290issn
1873-2380pii
S0021-9290(96)00122-4journal_volume
30pub_type
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