DIASTOLIC PROPERTIES, MYOCARDIAL WATER-CONTENT, AND HISTOLOGIC CONDITION OF THE RAT LEFT-VENTRICLE - EFFECT OF VARIED OSMOLARITY OF A CORONARY PERFUSATE

Background: Although myocardial edema is known to impair diastolic fil ling of the left ventricle, the interrelation of edema, histologic con dition, and function has not been quantitated sufficiently for extrapo lation to studies of multifactorial influences on diastolic properties . Methods: Accordingly, ACI rat hearts arrested at 4 degrees C underwe nt coronary artery perfusion with a cardioplegia solution that was eit her unaltered (288 mOsm/L, P-288 group, n = 6), diluted (144 mOsm/L, P -144 group, n = 6), or concentrated (380 mOsm/L, P-380 group, n = 6), Postmortem left ventricular pressure-volume curves and myocardial wate r content were measured. Myocardial samples were fixed in varying dilu tions of glutaraldehyde. After dehydration and paraffin embedding, ede ma was graded subjectively (0 to 5), and myocardial interstitial space s were determined by use of a semiquantitative method. Results: Mean n ormalized left ventricular filling volume at 20 mm Hg filling pressure in the P-144 group, 189 +/- 16 mu l (SEM), was reduced versus both th e P-288 (278 +/- 26 mu l) and the P-380 (332 +/- 18 mu l) groups (p < 0.05, ANOVA). Mean myocardial water content in the P-144 group, 80.7% +/- 1%, was increased versus the P-380 (76.7% +/- 0.4%, p < 0.05) but not versus the P-288 group (78.4% +/- 0.8%). In hearts preserved with 2.5% glutaraldehyde, mean edema grade and interstitial space in the P- 144 group (4.0 +/- 0.3) were increased versus the P-380 (1.8 +/- 0.3, p < 0.05) but not the P-288 group (2.7 +/- 0.5). Derived linear regres sions relate water content to filling volume and histologic condition. Conclusions: Coronary perfusate osmolarity is thus associated with pr edictable changes in myocardial water content, left ventricular fillin g volume, and edema. These correlations allow definition of new hypoth eses for the study of cardiac allograft rejection in patients and expe rimental animals.