Effects of adrenal steroids on the concentration of Na(+)-K+ pumps in rat skeletal muscle.
Since adrenal steroids have been shown to upregulate the concentration of Na(+)-K(+)-ATPase in cardiac muscle, similar effects could be expected in skeletal muscle. Following infusion of dexamethasone (0.02-0.1 mg/kg per day) for 7 days in 10-week-old rats, the total concentration of [3H]ouabain-binding sites rose by up to 22-42% in soleus, extensor digitorum longus, gastrocnemius and diaphragm muscle. Dexamethasone produced no or minute changes in the Na(+)-K+ contents of skeletal muscle. In contrast, infusion with aldosterone (0.02-0.5 mg/kg per day) for 7 days produced hypokalemia and a graded reduction in the K+ content of skeletal muscle, which was closely correlated to a downregulation of the [3H]ouabain-binding site concentration (r = 0.65-0.70; P < 0.001). The results indicate that in skeletal muscle high doses of glucocorticoids upregulate the concentration of Na(+)-K+ pumps whereas mineralocorticoids induce a downregulation, which is secondary to the concomitant K+ deficiency. Since adrenalectomy produced no significant change in [3H]ouabain-binding site concentration, basal levels of endogenous adrenal steroids seem to be of minor importance for the regulation of Na(+)-K+ pump concentration in skeletal muscle.
Dørup
I
I
Institute of Physiology, University of Aarhus, Denmark.
Clausen
T
T
D000305:Adrenal Cortex Hormones / Q000494:pharmacology*; D000315:Adrenalectomy; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013997:Time Factors
D000305:Adrenal Cortex Hormones; D005938:Glucocorticoids; D000450:Aldosterone; D010042:Ouabain; D003907:Dexamethasone; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium