Nonshivering thermogenesis in king penguin chicks. II. Effect of fasting
| Autor: | A. Lanni, F. Cohen-Adad, Claude Duchamp, P. Brebion, Hervé Barré, Jean-Louis Rouanet, G. Berne |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
medicine.medical_specialty
Physiology Cellular respiration Acclimatization Mitochondria Liver Mitochondrion Birds Electron Transport Complex IV Gastrocnemius muscle Oxygen Consumption Physiology (medical) Internal medicine Brown adipose tissue Respiration medicine Animals Cytochrome c oxidase biology Muscles Proteins Skeletal muscle Fasting Thermoregulation Mitochondria Muscle Cold Temperature Microscopy Electron medicine.anatomical_structure Endocrinology Adipose Tissue Liver biology.protein Energy Metabolism Body Temperature Regulation |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 261:R1446-R1454 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.1991.261.6.r1446 |
| Popis: | The effect of fasting on the energy metabolism of skeletal muscle and liver was investigated in cold-acclimatized short-term fasting (STF) (3 wk) and naturally long-term fasting (LTF) (4-5 mo) king penguin chicks, both groups exhibiting nonshivering thermogenesis (NST). A comparison was made with nourished cold-acclimatized controls. In these chicks, no brown adipose tissue deposits could be found on electron-microscopic observations of fat deposits. Protein content and cytochrome oxidase (CO) activity of tissue homogenates were measured in liver and pectoralis and gastrocnemius muscles, as were protein content, CO activity, and respiration rates of mitochondria isolated from these organs. Fasting-induced protein loss affected the pectoralis more than the gastrocnemius muscle, thus preserving locomotor function. In STF chicks, specific mitochondrial protein content and specific tissue CO activity were preserved but total organ CO capacity was reduced by half in pectoralis and liver following the fall in organ mass. In LTF chicks, both specific and total CO activity were drastically reduced in muscles, whereas specific CO activity was preserved in liver. In these LTF chicks, muscle mitochondria showed an energized configuration associated with an increased area of inner membrane in gastrocnemius. A reduction of respiratory control ratio (RCR) was observed in subsarcolemmal muscle mitochondria of STF chicks, whereas intermyofibrillar and liver mitochondria kept high RCR values.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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