The Effect of Cold Acclimation on the Size of Organs and Tissues of the Rat, With Special Reference to Modes of Expression of Results

Abstract

In experiments in which two groups of animals of different mean body weight are compared, individual organ weights of the animals can be expressed as absolute weights, as fractional weights, or as absolute weights statistically regressed onto constant body weights. The second, and commonest, mode of expression involves the assumption that the part is directly proportional to the whole, and this is shown to be unlikely for all organs except the muscle mass. Practical as well as theoretical justifications for the use of regressed weights (which utilize the actual slope of the line relating the organ weight to the whole) are given.The experimental data are from white rats kept for 4 weeks in a warm (30 °C.) or a cold (6 °C.) environment. It is shown that cold adaptation had no effect on brain, genitals, and lung weights, but that it reduced the growth of muscle, pelt, fat, skeleton, spleen, and thymus, and that it hypertrophied the liver, intestine, kidney, heart, and adrenals. Apparently cold acclimated rats are smaller than the controls mainly because they have a smaller muscle mass.

The effect of a low-protein diet and a cold environment on calorie intake and body composition in the rat

“…In contrast to the findings of Heroux (1963), there was a significant increase in the amount of fur after a comparatively short period in the cold. Barnett, Coleman & Manly (1959) found that mice kept and bred for many generations at -3' had relatively more fur than those kept and bred at ZIO, but they made no measurements over short periods.…”

“…The animals having the stock diet at 5' did not eat quite enough extra food to enable them to grow at the same rate as animals having the stock diet at 2 1 O , whichagrces with the findings of Heroux (1961Heroux ( , 1963. The animals having the low-protein diet and kept at Z I O lost weight but, in contrast to the findings of Andik et al (1963), none of them died during the 9 weeks of the experiment.…”

Effect of hypothermia on intestinal adaptation and carcinogenesis in the rat

“…This observation differs from previous work showing increased mucosal wet weight, villous height and crypt cell production rate in the small bowel of cold-acclimatised rats Sagor et al, 1982;Heroux & Gridgeman, 1958;. In these studies, however, animals were housed at lower temperatures (5-60C) small bowel.…”

The Red Cell and Plasma Volumes of the Rat and of Its Individual Tissues and Organs During Acclimation to Cold

“…Changes of this type probably reflect a temporary redistribution of blood concomitant with the disturbed hemostatic mechanisms. It could be that these changes relate to the hypertrophy of these organs during cold acclimation which has been reported for the rat by Heroux and Gridgeman (1957). Page and Babineau (19 53) have also reported a hypertrophy of the liver and kidneys of rats during prolonged exposure to cold.…”