Changes in performance of the surviving myocardium after left ventricular infarction in rats.
OBJECTIVE
The aim was to investigate left ventricular performance of infarcted hearts during scar formation and development of hypertrophy in the surviving myocardium.


METHODS
Hearts were perfused according to the Langendorff technique and left ventricular function curves were obtained by inserting a distensible balloon into the ventricular cavity. The isovolumetric systolic pressure was measured as diastolic pressure was changed from 0 to 25 mm Hg and during inotropic interventions produced by Ca and isoprenaline.


METHODS
Hearts were obtained from albino rats of either sex, 180-250 g, killed 1, 3, 7 or 14 d after left coronary artery ligation (n = 24) or sham operation (n = 26). Normal rats (n = 6) were used as additional controls.


RESULTS
After infarction, there was a progressive and almost parallel displacement of the ventricular function curves toward higher diastolic pressures. The positive chronotropic response to isoprenaline was similar in infarcted and non-infarcted hearts. The inotropic response to Ca and isoprenaline, however, was significantly depressed in the infarcted hearts throughout the observation period.


CONCLUSIONS
Hypertrophy in the surviving myocardium did not result in improvement of the left ventricular systolic function assessed under in vitro conditions during the first two weeks after infarction. The decreased inotropic response of the infarcted left ventricle to isoprenaline is likely to be dependent on the reduced Ca sensitivity of the surviving myocardium.
Mill
J G
JG
Departamento de Ciências Fisiológicas, Centro Biomédico da Universidade Federal do Espirito Santo, Vitória ES, Brasil.
Stefanon
I
I
Leite
C M
CM
Vassallo
D V
DV
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D006332:Cardiomegaly / Q000503:physiopathology*; D004195:Disease Models, Animal; D005260:Female; D006321:Heart / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000503:physiopathology*; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*
D007545:Isoproterenol; D002118:Calcium