Acetylcholinesterase (E.C.3.1.1.7) in the skeletal muscle and brain of rats after exercise and long-term training.

The activity of acetylcholinesterase was determined in the skeletal muscle and brain of rats after one exercise (running) and after long-term training of definite programme. Enzyme activity was determined by the colorimetric method of Hestrin. The results were subjected to statistical analysis by the t test of Student. An increase was demonstrated in AChE activity after one exercise in both tissues, but only in the muscle this increase was statistically significant. After long-term training the direction of this change was reversed. In the muscle the decrease was statistically significant, while the change in the brain was not significant.

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.

Respiratory activity of different parts of small intestine in starved and fed animals.

Using the manometric method of Warburg the respiratory activity of tissue homogenates of the duodenum, jejunum and ileum was studied in starved and fed rats. The respiratory activity of mitochondria isolated from these parts of the small intestine was determined as well. The intensity of respiration was greatest in duodenal homogenates. The respiratory activity of jejunal homogenates was only slightly lower, while that of ileum homogenates was lowest. Oxygen utilization of intestinal homogenates from fed animals was much higher, particularly in the ileum, than in starved animals. During 50 minutes of incubation theu tilization of oxygen fell most rapidly in the duodenum and slowest in the ileum, and at the end of incubation the values obtained in starved and fed animals differed only slightly. Mitochondria showed similar patterns of oxygen uptake intensity as analogous homogenates, but the effects of starvation and feeding on mitochondrial respiratory activity differed -- in fed animals this activity was lower than in starvation.

Effect of skeletal muscle denervaton on the activity of muscular acetylcholinesterase (E.C. 3.1.) in frog.

The activity of acetylcholinesterase (AChE 3.1.1.7.) was determined in skeletal muscle homogenates in frogs at various time intervals (15--24 days) after denervation. At the same time changes in AChE activity were compared with morphological changes of neuromuscular end plates in these muscles. Muscle denervation caused initially, within 30 hours, a rise in AChE activity by about 30% in relation to control muscles, followed by its fall to the control values after 4--6 days. The activity decreased further reaching lowest values 15 days after denervation, when it amounted to about 65% of the value of control muscles. After that time, when regeneration of nerves set in, the activity of AChe rose again returning to the control values after 24 hours. In the initial period of denervation no correlation was found between AChE activity and morphological changes in end plates. It was found however in the later period when degenerative changes were most pronounced as well as when reinnervation was in progress.