[Apoptosis in parathyroid of uremic patients with secondary hyperparathyroidism and the influence of Ca2+ and calcitriol on APO].

OBJECTIVE

To examine whether the alteration of apoptosis is pre sent in parathyroid (PT) tissue of hyperparathyroidism (HPTH).

METHODS

DNA strand breaks were sought by TdT-mediated dUTP nick end-labeling assay (TUNEL) and DNA gel electrophoresis in 4 specimens of normal PT tissue, 7 of primary HPTH (primary HPTH) and 9 of secondary HPTH tissue (secondary HPTH).

RESULTS

The data showed that the percentage of apoptotic cells was (1.3 +/- 0.4) % in normal PT, (3.9 +/- 0.7) % in primary HPTH and (5.6 +/- 0.8) % in secondary HPTH (P < 0.04), primary HPTH vs normal PT; P < 0.001, secondary HPTH vs normal PT respectively. There was no significant difference in the apoptotic incidence between primary and secondary HPTH. In vitro study, a greater amount of apoptotic TUNEL-positive cells was found 24 hours after exposure to high Ca(2+) (1.9 mmol/L) than to low Ca(2+) (0.5 mmol/L) concentration and 96 hours after treatment with high calcitriol (10(-7)mol/L) than with low calcitriol (10(-11) mol/L) concentration. However, no DNA ladder feature was observed in electrophoresis of DNA extracted from cultured parathyroid cells of HPTH.

CONCLUSION

It was shown that apoptosis did not decrease, but actually enhanced, in hyperplastic parathyroid tissue of patients with primary or secondary HPTH and that a high extracellular concentration of either Ca(2+) or calcitriol was capable of enhancing apoptosis in human parathyroid cells of secondary HPTH complicating chronic renal failure.