Hepatic Na,K-ATPase development in the rat.
The development of the enzyme Na,K-ATPase was studied in hepatic tissue from Sprague-Dawley rats at 18-20 days of gestation, 1, 3, 5, 7, 14, 21, and 30 days, and young adulthood (45 days). A developmental pattern was demonstrated for total and membrane-associated Na,K-ATPase activity. The activity in tissue homogenate, expressed per gram tissue, increased from late fetal life, 43.4 +/- 1.3 mumol Pi g liver-1 h-1, until 21 days of age, when an adult level of 187.3 +/- 19.6 mumol Pi g liver-1 h-1 was attained. A less pronounced ontogenic pattern was observed when enzyme levels were expressed as specific activity per milligram protein. The activity profile in a crude membrane preparation was similar. The potential for stimulation of enzyme activity by glucocorticoids was studied in 11-day-old animals injected with cortisone acetate (10 mg 100 g body weight-1) for 3 days. Enzyme specific activity was inducible: Specific activity was greater in cortisone-treated animals, 1.794 +/- .043 mumol Pi mg protein-1 h-1, versus controls, 1.258 +/- 0.043 mumol Pi mg protein-1 h-1 (p less than 0.01). We postulate that this developmental pattern for hepatic Na,K-ATPase activity may be a reflection of, or a contributing factor in, the ontogeny of sodium-dependent hepatic transport, such as that for bile salts.
Duffy
L F
LF
Department of Pediatrics, North Shore University Hospital, Manhasset, NY 11030.
Karl
P I
PI
Daum
F
F
Fisher
S E
SE
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003348:Cortisone / Q000031:analogs & derivatives / Q000494:pharmacology; D005333:Fetus / Q000187:drug effects / Q000201:enzymology; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase; D003348:Cortisone