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Characteristics of parathyroid hormone‐specific cyclic changes of glucose‐6‐phosphate dehydrogenase activity in the distal convoluted tubule of the guinea pig
Author(s) -
Sakaguchi Kazushige,
Fukase Masaaki,
Kobayashi Ikuo,
Fujita Takuo
Publication year - 1986
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650010304
Subject(s) - parathyroid hormone , medicine , endocrinology , chemistry , hormone , dehydrogenase , guinea pig , convoluted tubule , basal (medicine) , enzyme , kidney , biology , calcium , biochemistry , insulin
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.