Composition of Aortic Tissue from Copper-deficient Chicks

Abstract

The effect of copper deficiency upon the composition of connective tissue in the vascular system of the chick was investigated. The aortas of 4-week-old chicks, which had been fed copper-deficient and control diets, were processed so as to separate soluble collagen, insoluble or mature collagen and elastin. The fractions were analyzed for nitrogen, hydroxyproline, and hexosamine. Chicks fed the deficient diet weighed approximately 30% as much as the controls fed copper but, expressed as percentage of body weight, their aortas were twice as heavy as controls. Based on wet weight, the saline-soluble fraction from copper-deficient aortas contained nearly twice as much nitrogen, nearly 4 times as much hydroxyproline and significantly more hexosamine. The percentage of nitrogen removed by autoclaving and by sodium hydroxide extraction was appreciably greater in the deficient aortas but it was not collagen. On the basis of dry weight, the control aortas contained about 47% elastin and the deficient about 26% whether determined by sodium hydroxide or formic acid purification. The copper-deficient aortas accumulated a large fraction of non-elastin, non-collagen protein and had an increased concentration of soluble collagen. The elastin isolated by sodium hydroxide treatment contained a greatly elevated concentration of lysine and significantly less desmosine and isodesmosine.