Canine Right and Left Ventricular Cell and Sarcomere Lengths after Banding the Pulmonary Artery

Canine hearts were fixed with glutaraldehyde at zero transmural pressure 17 to 48 weeks after main pulmonary arterial banding. Tissues were taken from the trabeculae carneae at the ventricular right base, right apex, left base, and left apex. They were placed in osmium tetroxide, embedded in Epon 812, stained with Azure II methylene blue, and sectioned at ½ µ. The mean cell lengths of the hearts with main pulmonary arterial banding were greatest at the right base, 105±5 µ and left base, 103±5.7 µ. (The means ± SE are given.) The mean cell length at the left apex was 95±4 µ and that at the right apex was 92±5 µ. All were greater (P <0.001) than the cell lengths of normal hearts, 71±1.5 µ. The mean sarcomere lengths of the right ventricle with main pulmonary arterial banding (right base, 2.04±0.006 µ right apex, 2.18±0.004 µ) were less than those of normal hearts (right base, 2.41±0.006 µ right apex, 2.46±0.003 µ). The mean sarcomere length of the left base with main pulmonary arterial banding (2.10±0.01 µ) was less than the normal (2.16±0.002 µ); however, the mean sarcomere length of the left apex with main pulmonary arterial banding (2.28±0.005 µ) was the same as the normal. With main pulmonary arterial banding, both the right and left ventricular cell lengths increased more at the bases than at the apexes, and the sarcomere lengths decreased in the right base, right apex, and left base.