The effect of ouabain on metabolic rate in guinea-pigs: estimation of energy cost of sodium pump activity.
1. The effect of different doses of ouabain, an inhibitor of the sodium pump, or saline (9 g sodium chloride/1; the vehicle) on the metabolic rate of guinea-pigs weighing 500 g was measured by indirect calorimetry for 120 min. 2. Ouabain (0.02-0.07 nmol/g body-weight) decreased the oxygen consumption in a dose-related manner. When higher doses of ouabain (0.10 nmol/g body-weight or greater) were injected the animals were observed to shiver. Ouabain (0.07 nmol/g body-weight) reduced Na+,K+-ATPase (EC 3.6.1.3) activity of liver, kidney and skeletal muscle by 18.0 (SE 6.6), 21.5 (SE 6.0) and 21.9 (SE 6.8)% respectively. An Eadie-Hofstee plot of percentage decrease in O2 consumption v. percentage inhibition divided by dose of ouabain showed that maximal inhibition of O2 consumption was 39.4%. 3. It is concluded that Na pump activity contributed to about 40% of the resting O2 consumption.
Swaminathan
R
R
Department of Chemical Pathology, Prince of Wales Hospital, Shatin, N.T., Hong Kong.
Chan
E L
EL
Sin
L Y
LY
King
N S
NS
Fun
N S
NS
Chan
A Y
AY
D000818:Animals; D001693:Biological Transport, Active; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D008660:Metabolism / Q000187:drug effects*; D009132:Muscles / Q000201:enzymology; D010042:Ouabain / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase