Energy costs of ion pumping by animal tissues.
Results from recent in vitro studies indicate that in excess of 20% of the energy expenditure of skeletal muscle, duodenal epithelium and liver of domestic ruminants is to achieve Na+ and K+ transport across the plasma membrane. The energy cost of active Ca2+ transport is less clear but is likely less than 10% of the total expenditure of skeletal muscle at rest. Energy expenditure on Na+ and K+ transport was quite sensitive to the physiological state of the animal. During lactation, Na+ and K+ transport accounted for nearly half of the in vitro O2 uptake of skeletal muscle, duodenal epithelium and liver. The energetic cost of supporting Na+ and K+ transport was also elevated in young, as compared with older animals, by feed intake and by exposure to cold. Na+ and K+ transport appears to be a substantial component of the maintenance energy expenditure of ruminant tissues. Its variation, therefore, implies that change of maintenance energy expenditures with physiological state of the animal warrants serious attention.
Milligan
L P
LP
McBride
B W
BW
D000255:Adenosine Triphosphate / Q000378:metabolism; D000375:Aging; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003080:Cold Temperature; D004032:Diet; D004386:Duodenum / Q000378:metabolism; D004435:Eating; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D007774:Lactation; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009765:Obesity / Q000378:metabolism / Q000662:veterinary; D010101:Oxygen Consumption; D011188:Potassium / Q000378:metabolism*; D011247:Pregnancy; D012756:Sheep / Q000378:metabolism* / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D007473:Ion Channels; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium