Glycogen utilization by the white fibres in the pigeon pectoralis as main energy process during shivering thermogenesis

Effects of Short and Long Term Exercise on Intracellular Glycogen and Fat in Pigeon Pectoralis

“…In view of the present findings and those of the above-cited studies, it would appear that the bird relies to a large extent upon contraction of the white glycogen-loaded fibres for initiating immediate contraction of the pectoralis muscle but then quickly shifts toward a more selective recruitment of fibre types, calling upon the red fat-metabolizing fibres alone for effecting sustained activity. Theis conclusion is further supported by the recent observation (PARKER and GEORGE, 1974) that the respiratory exchange ratio (RQ) of the pigeon during electrical stimulation of the breast muscles shifted from a comparatively high value indicative of carbohydrate and fat utilization at the onset of contraction to a significantly lower quotient signifying an increased reliance upon fat alone as exercise continued.…”

Effects of Short and Long Term Exercise on Intracellular Glycogen and Fat in Pigeon Pectoralis

“…In view of the present findings and those of the above-cited studies, it would appear that the bird relies to a large extent upon contraction of the white glycogen-loaded fibres for initiating immediate contraction of the pectoralis muscle but then quickly shifts toward a more selective recruitment of fibre types, calling upon the red fat-metabolizing fibres alone for effecting sustained activity. Theis conclusion is further supported by the recent observation (PARKER and GEORGE, 1974) that the respiratory exchange ratio (RQ) of the pigeon during electrical stimulation of the breast muscles shifted from a comparatively high value indicative of carbohydrate and fat utilization at the onset of contraction to a significantly lower quotient signifying an increased reliance upon fat alone as exercise continued.…”

Influence of Hypothermia on the Carbohydrate Tissue Metabolism in Chickens

“…The effects are largely age-dependent, inter alia because various homoiothermic mechanismsincluding shivering thermogenesisbegin to function at various ages (6,12,23). The main site of shivering thermogenesis is the pectoral musculature, and the process implies increased glycogen consumption in the white fibres of the latter (16). Thyroxine seems to play an important role in the regulation of both shivering and non-shivering thermogeneses; in the former case, the involvement of the hormone takes place after a long delay, so that its physiological significance is evident only in accomodation phenomena (1).…”

Energetics of a long-distance migrant shorebird (Philomachus pugnax) during cold exposure and running

“…It is possible that the relative use of carbohydrates (CHO) for thermogenesis is higher in other species and at lower temperatures. For example, the use of glycogen as a thermogenic fuel during extreme cold exposure was investigated in the pectoral muscle of pigeons (Parker and George, 1975). The authors concluded that carbohydrates could become a significant fuel for heat production during high-intensity shivering.…”

Effects of Short and Long Term Exercise on Intracellular Glycogen and Fat in Pigeon Pectoralis

“…In view of the present findings and those of the above-cited studies, it would appear that the bird relies to a large extent upon contraction of the white glycogen-loaded fibres for initiating immediate contraction of the pectoralis muscle but then quickly shifts toward a more selective recruitment of fibre types, calling upon the red fat-metabolizing fibres alone for effecting sustained activity. Theis conclusion is further supported by the recent observation (PARKER and GEORGE, 1974) that the respiratory exchange ratio (RQ) of the pigeon during electrical stimulation of the breast muscles shifted from a comparatively high value indicative of carbohydrate and fat utilization at the onset of contraction to a significantly lower quotient signifying an increased reliance upon fat alone as exercise continued.…”

Influence of Hypothermia on the Carbohydrate Tissue Metabolism in Chickens

“…The effects are largely age-dependent, inter alia because various homoiothermic mechanismsincluding shivering thermogenesisbegin to function at various ages (6,12,23). The main site of shivering thermogenesis is the pectoral musculature, and the process implies increased glycogen consumption in the white fibres of the latter (16). Thyroxine seems to play an important role in the regulation of both shivering and non-shivering thermogeneses; in the former case, the involvement of the hormone takes place after a long delay, so that its physiological significance is evident only in accomodation phenomena (1).…”

Energetics of a long-distance migrant shorebird (Philomachus pugnax) during cold exposure and running

“…It is possible that the relative use of carbohydrates (CHO) for thermogenesis is higher in other species and at lower temperatures. For example, the use of glycogen as a thermogenic fuel during extreme cold exposure was investigated in the pectoral muscle of pigeons (Parker and George, 1975). The authors concluded that carbohydrates could become a significant fuel for heat production during high-intensity shivering.…”

Effects of Short and Long Term Exercise on Intracellular Glycogen and Fat in Pigeon Pectoralis

“…In view of the present findings and those of the above-cited studies, it would appear that the bird relies to a large extent upon contraction of the white glycogen-loaded fibres for initiating immediate contraction of the pectoralis muscle but then quickly shifts toward a more selective recruitment of fibre types, calling upon the red fat-metabolizing fibres alone for effecting sustained activity. Theis conclusion is further supported by the recent observation (PARKER and GEORGE, 1974) that the respiratory exchange ratio (RQ) of the pigeon during electrical stimulation of the breast muscles shifted from a comparatively high value indicative of carbohydrate and fat utilization at the onset of contraction to a significantly lower quotient signifying an increased reliance upon fat alone as exercise continued.…”

Influence of Hypothermia on the Carbohydrate Tissue Metabolism in Chickens

“…The effects are largely age-dependent, inter alia because various homoiothermic mechanismsincluding shivering thermogenesisbegin to function at various ages (6,12,23). The main site of shivering thermogenesis is the pectoral musculature, and the process implies increased glycogen consumption in the white fibres of the latter (16). Thyroxine seems to play an important role in the regulation of both shivering and non-shivering thermogeneses; in the former case, the involvement of the hormone takes place after a long delay, so that its physiological significance is evident only in accomodation phenomena (1).…”

Energetics of a long-distance migrant shorebird (Philomachus pugnax) during cold exposure and running

“…It is possible that the relative use of carbohydrates (CHO) for thermogenesis is higher in other species and at lower temperatures. For example, the use of glycogen as a thermogenic fuel during extreme cold exposure was investigated in the pectoral muscle of pigeons (Parker and George, 1975). The authors concluded that carbohydrates could become a significant fuel for heat production during high-intensity shivering.…”