BIOMECHANICAL SIGNALS IN THE CORONARY-ARTERY TRIGGERING THE METABOLICPROCESSES DURING CARDIAC OVERLOAD

Peculiarities in structure and deformability of epicardial conduit cor onary arteries are described. The thin wall of animal coronary artery contrasts the human coronary artery in which the remarkable wall thick ness is due namely by the intima thickness. Deformation in length and diameter of conduit coronary arteries, due to the left and right ventr icle volume increase, has been defined in non-beating canine heart. Ra mus interventricularis anterior being firmly tethered to the myocardiu m undergoes about 3 times larger deformation than ramus circumflexus. In anaesthetized dogs a 30% increase in blood pressure, elicited by ao rtic constriction, induces an increase in diameter of coronary artery, in segment length, in blood flow and consequently in shear stress whi ch represents a load for circumferentially running smooth muscle bundl es, longitudinally running smooth muscle bundles, as well as for the e ndothelium. The above load lasting 4 h is already reflected by an incr ease in total RNA content and [C-14] leucin incorporation in the left ventricle myocardium in the wall of ramus interventricularis anterior, not in ramus circumflexus. The findings fit completely with the diffe rent range of deformation of both the above coronary branches and indi cates an increase in proteosynthesis not only in myocardium, but in ra mus interventricularis anterior as well. An increase in ornithindecarb oxylase activity in coronary wall leading to an increase in biogenic p olyamines, is present in the case only, when blood pressure increase i s induced by infusion of noradrenaline.