THE ABSORPTION OF CAROTENE FROM ISOLATED INTESTINAL LOOPS

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Abstract
Absorption of [beta]-carotene from isolated intestinal loops of dogs was studied by means of photoelectric colori-metric detns. of the provitamin in the loop contents before and after absorption periods. Carotene was not absorbed in an analytically significant amt. when placed in the loops in concentrated solns. in cotton-seed oil without bile and pancreatic lipase. When carotene solns. were given along with hog or ox bile, significant amts. were absorbed. Similarly, small amts. were absorbed when carotene in oil was introduced into the loops with pancreatic lipase. When the carotene soln. was placed in the intestinal loops with both bile and pancreatic lipase, much larger amts. were absorbed. Pure bile salts were capable of promoting the absorption of carotene. Na desoxycholate was the most effective bile salt of those studied, but Na cholate and Na glycocholate also promoted carotene absorption. Results suggested that the choleate theory of the mechanism for the absorption of carotene should be minimized but not abandoned completely. In the presence of identical amts. of bile and lipase, the rate of absorption of carotene was greater when the initial amt. of carotene in the loop was increased. The inhibiting effect of mineral oil on the absorption of carotene was confirmed.