Muscle Protein and Strength Retention by Bears During Winter Fasting and Starvation

摘要: While maintaining the body temperature at only 5°C below normal, black bears in winter undergo 5 months when they do not eat, drink, urinate, or defecate. They have a high hypothalamic set point regulating fall hyperphagia and large fat reserve followed by complete anorexia with 50% reduction energy demands while their den. Cardiac skeletal muscle is preserved, perhaps expense of smooth labile protein reserves. Winter are reduced (1) no arousal bouts, (2) delayed implantation pregnant females, (3) urea hydrolysis to avoid urinary nitrogen water loss. Bears recycle almost 100% due transporters (UTB) bladder intestines which salvage for microbial intestine hepatic reammination ammonia into new amino acids protein. exhibit subtle EMG patterns respiratory sinus arrhythmia throughout denning period. As result conservation contraction patterns, during 150 days inactivity food deprivation show cardiac left ventricular atrophy. In addition, exhibits marginal loss of: protein, fiber number, size, conversion slow oxidative (MHC1) fast glycolytic (MHC2x) composition concomitant retention strength. truly adapted long periods immobility that can afford model study humans space flight hospital confinement.