Hyperphosphatemia modestly retards parathyroid hormone suppression during calcitriol-induced hypercalcemia in normal and azotemic rats

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dc.contributor.authorJara, A
dc.contributor.authorChacón, C
dc.contributor.authorFelsenfeld, AJ
dc.date.accessioned2025-01-21T01:10:13Z
dc.date.available2025-01-21T01:10:13Z
dc.date.issued2002
dc.description.abstractBackground/Aims: In in vitro studies, a high phosphate concentration has been shown to directly stimulate parathyroid hormone (PTH) secretion in a normal calcium concentration and to reduce PTH suppression in a high calcium concentration. In hemodialysis patients during dialysis-induced hypercalcemia, the effect of hyperphosphatemia on PTH secretion was less than in vitro studies. Our goal was to determine whether hyperphosphatemia retards PTH suppression during calcitriol-induced hypercalcemia in azotemic rats with hyperparathyroidism. Methods: Rats underwent a two-stage 5/6 nephrectomy or sham operations. After surgery, rats received a high phosphate diet (P 1.2%, Ca 0.6%) for 4 weeks to induce hyperparathyroidism and then were placed on a normal diet (P 0.6%, Ca 0.6%) for two additional weeks to normalize serum calcium values in azotemic rats. At week 7, rats were divided into five groups and before sacrifice received at 24-hour intervals, three doses of calcitriol (CTR) or its vehicle. The five groups and dietary phosphate content were: group 1 - normal renal function (NRF) + 0.6% P + vehicle; group 2 - NRF + 0.6% P + CTR; group 3 - renal failure (RF) + 0.6% P + vehicle; group 4 RF + 1.2% P + CTR; and group 5 - RF + 0.6% P + CTR. Results: In the two CTR-treated groups with marked hypercalcemia (groups 2 and 5), 15.52 +/- 0.26 and 15.12 +/- 0.13 mg/dl, respectively, stepwise regression showed that hyperphosphatemia retarded PTH suppression. When the two azotemic groups treated with CTR (groups 4 and 5) were combined to expand the range of serum calcium values, stepwise regression showed that hypercalcemia suppressed and hyperphosphatemia modestly retarded PTH suppression. Similarly, in groups 4 and 5 combined, correlations were present between PTH and both serum calcium (r = -0.70, p < 0.001) and serum phosphate (r = 0.64, p = 0.001). Conclusions: Hypercalcemia and high doses of calcitriol markedly reduced PTH secretion in azotemic rats despite severe hyperphosphatemia. Even though hyperphosphatemia did retard PTH suppression during hypercalcemia, its effect was small. Copyright (C) 2002 S. Karger AG, Basel.
dc.fuente.origenWOS
dc.identifier.doi10.1159/000065454
dc.identifier.eissn2235-3186
dc.identifier.issn1660-8151
dc.identifier.urihttps://doi.org/10.1159/000065454
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/96662
dc.identifier.wosidWOS:000179006900019
dc.issue.numero4
dc.language.isoen
dc.pagina.final888
dc.pagina.inicio883
dc.revistaNephron
dc.rightsacceso restringido
dc.subjectcalcitriol
dc.subjecthyperparathyroidism
dc.subjectparathyroid hormone
dc.subjectphosphate
dc.subjectrenal failure
dc.subject.ods03 Good Health and Well-being
dc.subject.odspa03 Salud y bienestar
dc.titleHyperphosphatemia modestly retards parathyroid hormone suppression during calcitriol-induced hypercalcemia in normal and azotemic rats
dc.typeartículo
dc.volumen92
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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