HEART ADAPTATION TO ACUTE PRESSURE OVERLOAD - INVOLVEMENT OF ENDOGENOUS PROSTAGLANDINS

The purpose of this investigation was to study the relationships between the contractile behavior of the heart and myocardial prostaglandins. Using an open-chest model in rabbits, we assayed the left ventricular tissue content of prostaglandins (PG)E and F(2α) and E and E(2α) at various intervals following acute pressure overload created by graduated aortic stenosis. The results suggest that the rabbits could be divided into two distinct groups based on specific hemodynamic changes following coarctation (systolic and diastolic pressure, dP/dt, and contractility index). The first group included rabbits whose adaptation to pressure overload was expressed as a gradual increase in the contractility index. The second group was comprised of rabbits that developed heart failure following coarctation. The increase in contractility in response to overload in the first group was paralleled by an increase in the content of PGE and PGE(2α) in the left ventricle, whereas, in rabbits with heart failure, the prostaglandin level did not rise above that of the control hearts. It is suggested that an increased endogenous prostaglandin content may be an important factor in adaptation to acute overload.