AJP - Endocrinology and Metabolism, Vol 250, Issue 4 475-E479, Copyright © 1986 by American Physiological Society
Involvement of glutathione oxidation reduction in parathyroid hormone secretion
J. J. Morrissey
This study determines whether calcium affects glutathione metabolism and
whether glutathione metabolism may influence parathyroid (PTH) secretion in
collagenase dispersed bovine parathyroid cells. Reduced glutathione (GSH)
and glutathione disulfide (GSSG) were measured fluorometrically and
enzymatically while PTH secretion was determined by radioimmunoassay. The
total GSH and GSSG content of parathyroid cells was found to range from
1.59 to 1.71 micrograms/mg cell protein, and this did not vary
significantly with changes in extracellular calcium. An increase in the
medium calcium concentration from 0.5 to 2.0 mM did, however, cause an
increase in GSSG from 0.43-0.54 to 1.19-1.20 micrograms/mg protein with a
concomitant decrease in GSH. The compound 2-cyclohexen-1-one was used to
deplete the cells of GSH at a low-calcium medium (0.5 mM) to levels seen in
high-calcium medium (2.0 mM). This treatment was found to inhibit PTH
secretion in the low-calcium medium, as if the cells were incubated in high
medium calcium. Both 2-cyclohexen-1-one and calcium caused a rapid decrease
in reduced GSH levels and in hormone secretion. The ketone was not found to
affect cellular protein synthesis, indicating that there was no nonspecific
toxic effect of this treatment on the cells. These results suggest that
changes in the calcium concentration of the medium affect the GSH/GSSG
ratio of dispersed parathyroid cells. Changes in the GSH/GSSG ratio induced
by calcium may be related to changes in PTH secretion.
