Pulmonary artery banding for 2 weeks in cats caused significant increases in myocyte cross-sectional area and diameter with a concurrent increase in interstitial tissue volume density.
What are the early morphological alterations in right ventricular myocardium subjected to pressure overload in a cat model?
Early right ventricular pressure overload in cats leads to increased myocyte size and interstitial tissue proportion without changes in organelle density, which may underlie early contractile dysfunction.
Pressure overload of the right ventricle results in an increase in ventricular mass. It also results in abnormal in vitro contractile function in advance of the onset of congestive heart failure as determined in papillary muscles removed from these ventricles. To correlate these functional abnormalities with any early underlying morphological changes, a band was placed around the proximal pulmonary artery of cats. This band restricted the lumen to 20% of normal and was left in place for 2 weeks. At that time, hemodynamic variables were measured to insure that right ventricular pressure overload had been produced. The hearts were then perfusion fixed, and papillary muscles from the right ventricle were prepared for light and transmission electron microscopy. Quantitative morphological data were obtained for the volume density both of several tissue components and of several organelles. It was found that there are significant increases in myocyte cross-sectional area and diameter in hypertrophied tissue with a concurrent increase in the volume density of interstitial tissue. There are no alterations in the volume density of organelles in the hypertrophied myocytes. We suggest that the substantial increase in the proportion of connective tissue and the decrease in the surface area to volume ratio that accompany pressure overload cardiac hypertrophy may be early underlying structural changes that relate directly to the abnormal contractile function found in this type of hypertrophy.
Marino et al. (Tue,) conducted a other in Right ventricular pressure overload. Pulmonary artery banding vs. Normal tissue was evaluated on Quantitative morphological data for volume density of tissue components and organelles, and myocyte dimensions. Pulmonary artery banding for 2 weeks in cats caused significant increases in myocyte cross-sectional area and diameter with a concurrent increase in interstitial tissue volume density.