Respiratory activity of various parts of the small intestine in fasted and fed animals. Part II. Respiratory activity of the small intestine in guinea pigs.

The aim of this work was to investigate the respiratory activity of three parts of the small intestine: duodenum, jejunum and ileum in guinea pigs, to compare the intensity of oxygen consumption by these parts in hungry and fed animals, and to find possible differences in the intensity of intestinal respiration between guinea pigs and rats. In guinea pigs the intensity of respiration of intestinal homogenates was nearly twice smaller than in rats. similarly, however, as in rats intestinal homogenates of guinea pigs had greater respiration intensity after feeding than while the animals were fasting. The metabolic gradient in the small intestine of guinea pigs was somewhat different, the intensity of respiration was highest in the jejunum, in the duodenum it was slightly lower or equal to that in the ileum it was the lowest. The intensity of mitochondrial respiration was similar in guinea pigs as in rats, and the metabolic gradient in mitochondrial respiration was also similar in three studied parts of the intestine. The effects of fasting and feeding were, however, different than in homogenates. the mitochondria of fed animals consumed less oxygen than those of fasting animals. These changes in respiration were not connected with any changes in the amounts of mitochondrial protein since they were similar in fasting and in fed animals.