Abstract
Summary
Studies were made on (a) human papillary muscles derived during open heart surgery in various degrees of failure, and (b) experimentally produced failing guinea pig hearts. There was a significant decrease in norepinephrine from 1.22 to 0.34 μg/g in the experimental guinea pig hearts as compared to normal. There was also a significant decrease in norepinephrine from 0.37 to 0.16 μg/g in human papillary muscle as the degree of failure increased. Glucose-6-phosphate decreased significantly from 0.30 to 0.09 μmoles/g in the human papillary muscles with increasing degree of failure. Similarly there was a significant rise in glycogen from 3.42 to 6.56 mg/g in the guinea pig hearts and from 5.69 to 8.89 mg/g in the papillary muscles. The differences in glycolysis and citric acid cycle intermediates were not significant. The ATP/ADP ratio decreased from 3.84 in grade II failure to 2.47 in grade IV failure. This ratio is a reflection of the degree of aerobiosis in mitochondria metabolism and indicates in failure a shift to more aerobiosis. The values on guinea pig heart adenyl cyclase activity were not statistically different, being 16.9 and 18.7 μmoles/100 g of tissue/15 min.
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