PROTEIN-METABOLISM IN CORONARY WALL AFFECTED BY CARDIAC LOAD

The relation between biomechanics of conduit coronary artery and metab olic processes in its wall were studied in cardiac pressure overload, in anaesthetized dogs. Two sorts of forces and/or coronary deformation s were followed: (1) radial and length deformation of ramus interventr icularis anterior (RIA) due to ventricle volume changes, and (2) shear stress in ramus circumflexus (RC) ensuing the blood flow changes. Inc rease in aortic pressure (33.9 +/- 2.30%) accompanied an increase in R IA diameter (4.6 +/- 0.38%) and an increase in segment length (8.0 +/- 1.0%) indicating that both circumferential and longitudinal oriented muscle bundles were loaded. Increase in RC blood flow (55.6 +/- 4.0%) and diameter (3.8 +/- 0.3%) resulted in an increase of shear stress (3 5.15 +/- 11.16%) that affects particularly the endothelial cells. Two hours lasting cardiac load suggested a tendency, 4 h lasting load resu lted in a significant increase both in RNA content (11.06 +/- 4.68% an d 9.05 +/- 0.72%) and in [C-14]leucine incorporation (53.59 +/- 13.75% and 48.41 +/- 16.16%) in the myocardium and RIA wall, respectively. N o change was found in RC wall. The process was reversible, 2 h after t he load had ceased. The heterogeneity of metabolic processes reflected closely the heterogeneity in coronary deformation.