Enzyme activation of human prolactin: a potential basis for a bioassay.
Small cultures of human amniotic cells were preincubated for 24 h. Human prolactin was then added to the medium. After a further short period of incubation the tubes were chilled, the medium removed and the cells rinsed with saline. The tubes then received cold Tris-sucrose and were frozen, to disrupt the cells. After thawing, adenosine triphosphatase (ATPase) and p-nitrophenyl phosphatase (PNPase) were measured. Buffer was added containing either ATP or PNP and the tubes were incubated for 30 min. Inorganic phosphate released from ATP and p-nitrophenol was measured spectrophotometrically. Prolactin stimulated both enzyme activities. The ATPase log dose-response curve was linear between approximately 12.5 and 200 mIU/l. It was inhibited by ouabain. Isobutyl-1-methylxanthine inhibited the ATPase but not the alkaline phosphatase activity. One of these human amniotic cell enzymes may provide the basis for a sensitive bioassay for human prolactin.
Ryle
M
M
University of Sheffield, Department of Obstetrics and Gynaecology, Jessop Hospital for Women, UK.
Bertrand
P V
PV
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D009597:4-Nitrophenylphosphatase / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000494:pharmacology; D000650:Amnion / Q000032:analysis*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010042:Ouabain / Q000494:pharmacology; D011247:Pregnancy; D011388:Prolactin / Q000032:analysis*
D010042:Ouabain; D011388:Prolactin; D004492:Edetic Acid; D009597:4-Nitrophenylphosphatase; D000251:Adenosine Triphosphatases; D015056:1-Methyl-3-isobutylxanthine