Characteristics of parathyroid hormone-specific cyclic changes of glucose-6-phosphate dehydrogenase activity in the distal convoluted tubule of the guinea pig.
The effect of parathyroid hormone (PTH) on the time course of glucose-6-phosphate dehydrogenase (G6PD) activity in the distal convoluted tubule of a vitamin D-depleted guinea pig was determined using quantitative cytochemistry. G6PD activity decreased to the stable basal level 5 hrs after the initiation of the kidney segment maintenance cultures. The exposure of the tissues to 1 pg/ml of bovine PTH-(1-84) induced a cyclic change of G6PD activity, whereas neither carboxyl-terminal PTH nor other hormones tested showed such activity. After a 16-min exposure to bovine PTH-(1-84), the peak height of each cycle began to decrease until it disappeared at 34 min. The second exposure to this hormone at 46 min reinduced a similar cyclic change with a similar peak, indicating full viability of the cells. When bovine PTH-(1-84) was incubated with an excess amount of anti-bovine PTH antibody, the PTH-induced G6PD activity was completely abolished. Throughout a 14-min exposure to either human PTH-(1-84), human PTH-(1-34) or bovine PTH-(1-84), similar cyclic changes were observed with the constant peak height regardless of the dose (10(-16)-10(-12) M), although the cycle length shortened progressively as the dose was increased. They were equipotent on a molar basis between the concentrations of 10(-16) and 10(-13) M at 6 min of hormone exposure. The present data demonstrate that the cytochemical bioassay of PTH in a vitamin D-depleted animal is based on a dose-dependent difference in the time course of G6PD activity.
D000818:Animals; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007684:Kidney Tubules / Q000201:enzymology*; D007686:Kidney Tubules, Distal / Q000187:drug effects / Q000201:enzymology*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010507:Periodicity; D010758:Phosphorus / Q000097:blood; D014808:Vitamin D Deficiency / Q000201:enzymology
D010281:Parathyroid Hormone; D010758:Phosphorus; D005954:Glucosephosphate Dehydrogenase; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium