The tail-cast suspension system was used as a ground-based model of weightlessness to study the effects of reduced weight-bearing (unloading) and attendant atrophy on carbohydrate metabolism in the rat soleus muscle. Changes in glycogen metabolism during unloading were biphasic. The initial phase, which took place during the first 24 hours, was characterized by increased glycogen concentrations, the result of decreased glycogenolysis. This glycogen accumulation in turn decreased the glycogen synthase activity ratio. These alterations were maintained thereafter. A similar glycogen increase was seen in the soleus unloaded by hypogravity. A rapid decline in glucose uptake also occurred during this initial phase of unloading, both in the absence and presence of insulin. During the second phase of this unloading response, beyond 24 hours, there was an increase in the sensitivity of the soleus to insulin for glucose uptake that coincided with the onset of muscle atrophy. However, this increased insulin sensitivity was not seen for glycogen synthesis, indicating differential regulation of these two processes by insulin. The enhanced insulin sensitivity likely resulted from an increase in the binding capacity for the hormone, resulting from no increased turnover of the insulin receptor during unloading. Additionally, the onset of increased insulin sensitivity coincided with a return to normal of basal glucose uptake, despite the continued unloading. When the 3-day unloaded soleus was reloaded, carbohydrate metabolism returned to normal after a triphasic response. Within two hours, the glycogen concentration decreased below control levels, due to increased glycogenolysis. During the second phase of reloading, from two to 24 hours, glycogen accumulated dramatically due to an enhanced capacity of the muscle for glycogenesis. Insulin sensitivity returned to normal by 24 hours of reloading. In the final phase, beyond 24 hours, glycogen decreased to control values. An uncoupling of the inverse relationship between glycogen and the activity ratio of glycogen synthase was seen beyond four hours of reloading. These effects of unloading and reloading were not due to systemic factors, as the extensor digitorum longus was unaffected. It is apparent that the unloaded soleus is a potent model with which to study the individual factors that regulate carbohydrate metabolism in skeletal muscle.

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Glycosaminoglycan-peptide complexes (GAG-P) and some proteoglycans from long bones, breast muscle, comb, crop, gizzard, heart, infundibulum, intestines, isthmus, kidney, leg muscle, liver, lung, magnum, oesophagus, ovary, pancreas, proventriculus, skin, shell gland, spleen, trachea, vagina, wattle, cecum, egg yolk and adipose tissue of the white leghorn hen were isolated and analysed for constituent units. Techniques of identification included infrared spectroscopy, cellulose acetate electrophoresis, colorimetric reactions, ion-exchange chromatography and scanning electron microscopy. The in vivo incorporation of {('14)C}-glucosamine (GlcN) and {('14)C}-galactosamine (GalN) for 1-, 2-, 120-, and 240-hour periods, and {('14)C}-glucose (Glc) and {('14)C}-galactose (Gal) for a 48-hour period into whole tissues, acetone-extracted tissues and GAG-P were investigated. Radioactivity in excreta was measured. ('14)CO(,2) from the {('14)C}-hexose treated birds was determined. In vitro incorporation of ('14)C from {('14)C}-Glc, {('14)C}-Gal, {('14)C}-GlcN, {('14)C}-GalN, {('14)C}-fructose and {('14)C}N-acetylneuraminic acid were studied.

The purpose of this study was to examine the effects of exercise of short duration, and the effects of re-exercise on carbohydrate metabolism. I feel that the levels of severe exercise studied approximate the levels of severe exercise which a rainbow trout probably experiences in its natural environment. The level of blood lactate, blood hemoglobin, muscle lactate, muscle glycogen, and liver glycogen were determined in unanesthetized, intact, one and one-half year old rainbow trout acclimated to 10.5°C. Samples were taken immediately after exercise of 3 seconds to 5 minutes, after recovery of 3 minutes to 60 minutes, and after re-exercise of 3 seconds to 5 minutes. The results indicate that exercise of even the shortest duration studied causes an immediate increase in the level of blood lactate, muscle lactate, and blood hemoglobin. Exercise also causes an immediate decrease in muscle glycogen, but does not cause a change in the level of liver glycogen. Changes during the 60 minute recovery period are slight. In general, the effects of re-exercise after a 60 minute recovery period are additive. A correlation analysis between muscle glycogen and muscle lactate indicates that there is a source of muscle lactate other than muscle glycogen at exercise levels of long duration. The source of this muscle lactate does not appear to come from liver glycogen. The energy may be supplied by catabolism of protein or lipid, or by absorption of foodstuffs from the gut. This study provides evidence that rainbow trout are not well adapted for recovery from severe exercise of short duration. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

A parent and pleomorphic strain of the dermatophyte Microsporum gypseum were cultured in chemically defined media under standardized conditions in order to compare growth kinetics, changes in chemical composition with time, and basic carbohydrate metabolism. In general, the two strains were similar in most respects, although some differences were observed. The growth potential of the pleomorphic form was greater than that of the parent form under most conditions examined. The kinetics of mass increase in liquid culture, and of colonial growth on solid culture were examined and compared to those of other fungi, and to those of bacteria. The equations describing bacterial colonial extension were tested against both strains of M. gypseum, and found to be invalid. The rate of subsurface mass increase was exponential with time. Both strains were found to possess some of the enzymes of the Embden-Meyerhof and hexose-monophosphate glycolytic pathways, the tricarboxylic acid cycle, and isocitrate lyase. No enzymes utilizing glyoxylate were detected, nor were the enzymes exclusive to the Entner-Doudoroff pathway. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

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published_or_final_version / Physiology / Master / Master of Philosophy

published_or_final_version / Physiology / Master / Master of Philosophy