Biomedical subjects
Publications and source records attributed to E Villa-Moruzzi.
Glycogen levels in the extensor digitorum longus of the rat undergo different changes after cutting the sciatic nerve compared with the destruction of the lumbosacral spinal cord. The differences most probably are due to early changes of the endocrine (adrenal and pancreatic) function after the latter type of denervation.
Adrenaline causes of 5 fold increase of glucose-6-phosphate and of glucose-1-phosphate both in the white extensor digitorum longus and in the red soleus (where the levels of the two sugar phosphates are significantly lower). On the other hand, UDPG levels--which are similar in the two muscles--are significantly decreased after adrenaline. It has been concluded that the levels of glucose-1-phosphate and of UDPG in muscle are not bound to change together.
Native glycogen was prepared from intact and 12 and 36 h denervated white and red rat muscles, ultracentrifuged on a sucrose density gradient (3) and the fractions stained by the iodine method (4). An increase of the optical density of the fractions showing a relatively high density was observed, which may be related to the well known changes of muscle glycogen levels after denervation.
Adrenaline administration which leads to glycogen changes different in fast and slow twitch muscles (Gorski, 1978) causes very similar acute changes in the activities of glycogen synthase I and of glycogen phosphorylase 'a' in these two types of rat muscle.
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Glycogen synthase (GS), Branching enzyme (BE), Glycogen Phosphorylase (GPho) and the Debranching enzyme (DE) activities were studied in the white extensor digitorum longus (ELD) and in the red soleus (S) muscles of rats during the developmental period from birth to the young adulthood. During the first days of postnatal life all enzyme activities similarly increase in both ELD and in S. BE and DE seem to rise faster and reach the adult levels earlier than GS and GPho. Significant differences can be seen between ELD and S by age 14--21 days: glycogenolytic enzymes rise higher in the ELD, GS activity is similar in both muscles whereas BE activity is higher in S. All these develop changes are completed in 25 days. Thereafter, only GPho activity in the ELD continues to slowly increase.
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