Morphology and Metabolism of Intact Muscle Cells Isolated from Adult Rat Heart

Morphologically intact muscle cells were prepared by perfusing adult rat hearts with a balanced salt medium containing 0.1% collagenase and 0.2% hyaluronidase. Yields of intact cells representing up to 25% of the weight of the heart were obtained. The cells separated along the line of the intercalated discs, with cleavage of desmosomes but with tearing of the plasma membrane in the region of the gap junction, so that when two contiguous cells were parted, the gap junction was retained intact attached to one of the cells. The fine structure of undamaged cells was indistinguishable from that of normal myocardial cells in situ, whereas damaged cells characteristically revealed numerous cytoplasmic vacuoles, clumping of myofilaments, and blebbing of the cell membrane, but morphologically normal mitochondria. The earliest lesion detected was a dilatation of the T (transverse tubular) system. Respiration in the intact cells was linear for 30 to 60 minutes and approximately two to three times the rate observed with heart muscle slices or the arrested isolated perfused heart. Oxygen uptake was stimulated by pyruvate but not by lactate. These observations demonstrate the feasibility of preparing intact isolated cells from adult rat heart and their potential value in histologic, pharmacologic, and metabolic studies.