Changes in collagen content in the residual myocardium surviving after infarction in rats. Influence of propranolol or hydralazine therapy.
The changes occurring in the collagen content in the residual myocardium after infarction have been poorly studied. The aim of this study was to determine the changes in the collagen content in the right and left ventricular muscle of chronically infarcted hearts. Male albino rats were submitted to ligature of the left coronary artery to produce infarction (Inf). Controls underwent a sham surgery (Sh). Inf rats were divided into groups designed to receive chronic therapy with propranolol (Prop, 1 g/l, n = 10) or hydralazine (Hydr, 0.125 g/l, n = 10) dissolved in the drinking water. One group of Inf rats (n = 12) and the Sh group (n = 10) received no treatment. The animals were killed 1 month after surgery to obtain the cardiac wet weights and to determine protein and hydroxyproline (OH-Pro) concentrations in the right ventricle (RV) free wall and in the left ventricular remaining muscle (LV), including the interventricular septum. Inf determined a 42% increase of the RV weight to body weight ratio (Sh = 0.57 +/- 0.04 mg/g; Inf = 0.81 +/- 0.06 mg/g; p < 0.05) and a 64% increase of OH-Pro concentration (Sh = 450 +/- 25 micrograms/g; Inf = 738 +/- 32 micrograms/g; p < 0.05). In Inf hearts the LV OH-Pro concentration increased similarly as in the RV. No effect of drug therapy was observed in the LV. In the RV however, propranolol reduced the hypertrophy and the OH-Pro concentration by the same amount (around 30%). Hydr on the other hand reduced OH-Pro and tended to increase hypertrophy. We conclude that a similar collagen deposition occurs in the myocardium of both ventricles after infarction in rats. Prop and Hydr were able to partially reduce this collagen increase in the right but not in the left ventricle.
Leite
C M
CM
Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, Brazil.
Gomes
M G
MG
Vassallo
D V
DV
Mill
J G
JG
D000818:Animals; D003094:Collagen / Q000378:metabolism*; D006830:Hydralazine / Q000627:therapeutic use*; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D011433:Propranolol / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar
D006830:Hydralazine; D003094:Collagen; D011433:Propranolol