Sheng H P, Huggins R A, Garza C, Smith E O
Growth. 1985 Spring;49(1):141-53.
The influence of age on patterns of K/N ratios (mEq/g) for fat-free whole body organs and tissues was analyzed for the guinea pig, ages 1 to 80 days (82 to 849 g); for the pig, 0 to 89 days (151 to 33,650); and for the beagle, 0 to 383 days (252 to 13,065 g). Strong correlations existed between total K, total N, and fat-free wet weight (FFWW). Mean whole body K/N ratios were 2.57 +/- 0.241 for guinea pigs, 2.53 +/- 0.50 for pigs, and 1.79 +/- 0.27 for beagles. Increase in body weight of the beagle and of the components, skeletal muscle and nonmuscle (whole animal minus skeletal muscle), were divisible into two statistically significant periods: the first from 0 to 62 days, the second from 63 to 383 days. For the first period, the K/N ratio for the whole animal was 1.70 +/- 0.33, for nonmuscle was 1.61 +/- 0.34, and for skeletal muscle was 2.08 +/- 0.50; for the second period, the values were 1.93 +/- 0.22, 1.25 +/- 0.18, and 2.82 +/- 0.83, respectively. Mean K/N ratios of organs and tissues of the pig and beagle differed significantly from mean whole body K/N ratios, with the exception of liver for the beagle and miscellaneous for the pig. Patterns of K/N ratios during increases in FFWW were species-specific for total body as well as for various tissues and organs. As FFWW increased, the whole body K/N ratio did not change significantly in the guinea pig, but decreased significantly in the pig because of the decreased ratio for skeletal muscle. As FFWW of the beagle increased in the first growth period, the slope for the whole body K/N ratio did not differ statistically from zero, although the mean measured ratio increased significantly for liver and skeletal muscle. This increase was counter-balanced by a statistically significant decrease in ratios for skin and skeleton. FFWW continued to increase in the second growth period and the whole body K/N ratio increased, primarily the result of significantly increased ratios for liver and skeletal muscle.(ABSTRACT TRUNCATED AT 400 WORDS)
