Na+,K+-ATPase enzyme units in lean and obese (ob/ob) thyroxine-injected mice.
The possible involvement of Na+,K+-ATPase in the etiology of obesity in the obese (ob/ob) mouse was explored. The number of Na+,K+-ATPase enzyme units in skeletal muscle, liver, and kidneys from 4- and 8-wk-old obese and lean mice was estimated from saturable [3H]ouabain binding to particulate fractions. Neither phenotype nor age altered the Kd value for ouabain binding in these three tissue preparations. The total number of [3H]ouabain binding sites in hindlimb muscles was 35--55% lower in 4- and 8-wk-old obese mice than in their lean counterparts. However, the total number of [3H]ouabain binding sites in liver and kidneys of obese mice was similar to values observed in their lean counterparts. Because it has been suggested that ob/ob mice are hypothyroid, we investigated the response of Na+,K+-ATPase in these mice to thyroid hormone treatment (approximately 5 microgram thyroxine/day for 2 wk). The number of [3H]ouabain binding sites in the three tissues increased in both obese and lean mice injected with this relatively large dose of thyroxine, but the obese mice were 2--3 times more responsive than lean mice.
D000367:Age Factors; D000818:Animals; D007037:Hypothyroidism / Q000150:complications / Q000188:drug therapy; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology; D009765:Obesity / Q000150:complications / Q000201:enzymology* / Q000235:genetics; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013974:Thyroxine / Q000627:therapeutic use
D000254:Sodium-Potassium-Exchanging ATPase; D013974:Thyroxine