236 INFLUENCE OF TEMPERATURE ON BIOLOGICAL SYSTEMS 



peratures for maintaining the vitality when such tissues have been isolated 

 and thereby deprived of their blood supply. In 1931 Bucciante (40) 

 reported that chick organs in Ringer's solution at 5°C survived for 

 long periods. Skin lived 21 days and even the most sensitive organ, the 

 liver, survived for 3 days. Hetherington and Craig (88) kept chick 

 heart muscle at 0°C for 15 days without apparent effect on vitality. 

 Waterman (183) tested rabbit and chick tissues and organs and deter- 

 mined that 5°C was optimal for survival. At this temperature brain 

 survived several days, intestine for a longer period and skin for 3 weeks. 

 Pomerat and Lewis (152) found newborn human tissues slightly less 

 resistant to the effects of cooling than the corresponding tissues of the 

 chick. The assumption from this line of experimentation is that tempera- 

 tures in the vicinity of 5°C are probably optimal for survival of avascular 

 or anoxic newborn human organs. 



The effects of hypothermia upon the intact newborn animal have been 

 but little studied. Fairfield (62) found that newborn rats made no attempts 

 to control temperature and at 3 days of age produced only a transient 

 rise in metabolism. During cooling the metabolic rate fell with temperature 

 and at 3°C was immeasurably small. She reports complete recovery of 

 an animal which remained apneic for 108 minutes. Electrocardiographic 

 studies show that the infant heart reacts in a similar fashion to that of 

 the adult. Interference with conduction, irregular QRS impulses, the de- 

 velopment of 2:1 or 3:1 heart block and occasional fibrillation were 

 observed. In spite of these effects one infant recovered after 82 minutes 

 of asystole. 



HISTOLOGICAL STUDIES 



Studies of tissues of refrigerated appendages subjected to tempera- 

 tures in the neighborhood of 0°C show no evidence of damage to nerves, 

 blood vessels, glands and skin (161). Generalized hypothermia, like- 

 wise, has been reported to produce little or no change from the normal 

 microscopic appearance of tissues (179, 56). However, recently Krocker 

 (100) reported conflicting results from a careful study of livers, kidneys 

 and adrenals of dogs exposed to hypothermia for 2^/2 hours. She found 

 depletion of glycogen in the liver, vaculolation of cells in the adrenal 

 cortex, tubular damage in the kidneys and accumulations of fat droplets 

 in all three organs. Other reports of tissue damage resulting from hypo- 

 thermia include vacuolation of cells of adrenal cortex and medulla (173), 

 kidney lesions, chiefly in distal convoluted tubules (105), reduction of 

 urinary output (158), associated with renal cortical ischemia (130). 

 These changes are in sharp contrast with the behavior of isolated tissues 



