An approach to the genesis of idiopathic cardiomyopathy.

The turnover of cholesterol of red blood cells in healthy hamsters was faster than that in cardiomyopathic hamsters. The uptake of 2-deoxy-D-glucose by heart cells was more rapid in the diseased hamsters compared with that of the healthy ones. Freeze-etch study of heart cells disclosed a difference of membrane structure between the two groups.

Cardiomyopathy in vitro.

Phase contrast microscopy of cultured embryonic heart cells showed the beating frequency decreased more rapidly and the regularity the rhythm of of the beating cells was lost sooner in heart cells from cardiomyopathic hamsters than from the control hamsters. Studies of cultured heart cells by differential interference contrast (with Nomarski's prism) and by electron microscopy revealed a significant impediment in the maturation of the sarcomeric units in the diseased animals compared to controls. The incorporation of [14C] leucine into acid-insoluble fractions was studied, and no significant difference in incorporation between the two groups was found.

Morphological and biochemical studies on the heart of the cardiomyopathic Syrian hamster.

Histological and ultrastructural observations of embryonic hearts and cultured cells from hamsters with inherited cardiomyopathy (BIO 14.6 line) showed a significant delay in maturation of the sarcomeric units in comparison with those of unrelated healthy control hamsters. Phase-contrast microscopic observation of the cultured cardiomyocytes revealed more rapid diminution of beating frequencies in the diseased hamsters than in the controls.

Discrimination of single transport systems. The Na plus-sensitive transport of neutral amino acids in the Ehrlich cell.

Uptake of methionine, alpha-aminoisobutyric acid, and alpha-(methyl-amino)-isobutyric acid has been shown to occur by at least two transport systems, one sensitive and the other insensitive to the Na(+) concentration. For alpha-aminoisobutyric acid and its N-methyl derivative, the Na(+)-insensitive uptake is not concentrative and its rate increases almost linearly with concentration within the range examined. In contrast, the Na(+)-insensitive uptake of methionine is concentrative and subject to inhibition by such amino acids as phenylalanine, leucine, and valine, although not in a manner to indicate that the uptake is mediated by a single agency.