The effect of phosphate on PTH release from parathyroid tissue and cultured cells in vitro

Objective To observe the levels of PTH secretion in primary cultured parathyroid cells and par-athyroid tissues stimulated by high phosphate.Methods The parathyroid glands of 28 Wistar female rats were success-fully resected by surgical operation under dissection microscope and were prepared for primary parathyroid cell culture and tissue culture.The cells and tissues were identified by histomorphology and PTH measurement and then cultured.Parathyroid tissues and cells were divided into 2 groups respectively as below: tissue groups:control group(TN,Pi 1.0mml/l,Ca 1.25mmol/l),experimental group(TH,Pi 3.5mmol/l,Ca 1.25mmol/l);cell groups:control group(CN,Pi 1.0mml/l,Ca 1.25mmol/l)and experimental group(CH,Pi 3.5mmol/l,Ca 1.25mmol/l).The medium was changed every two days.And the parathyroid hormone obtained from the supernatant for 0h,4h,12h,24h,48,72h,5d,7d,9d was measured.Results Parathyroid glands were identified by histomorphology and PTH measured.The PTH secretion curves of parathyroid cells and tissues incubated in normal phosphate and normal calcium medium were similar,and the peak time was 48h.Varing medium phosphate(1mM or 3.5mM) have no effect on PTH secretion(P 0.05) in cell groups.But when PTG tissues were incubated in high phosphate medium,PTH levels could increase to 10-fold higher than baseline at 48h.There was a significant difference between group TH and group TN at the same time except H0(P 0.01).Conclusion High phosphate had a direct effect on PTH release from parathyroid tissue but not from dispersed parathyroid cells.Parathyroid tissues should be chosen to study the effect of phosphate on parathy-roid function in vitro,and the time selected should be within 48h.