Document Detail

Both duration and degree of hypercalcemia influence the reduced parathyroid hormone response to hypocalcemia after hypercalcemia.
MedLine Citation:
PMID:  12697043     Owner:  NLM     Status:  MEDLINE    
The stimulation of parathyroid hormone (PTH) secretion by hypocalcemia is reduced when hypocalcemia is preceded by hypercalcemia. The present study investigates whether the duration and degree of hypercalcemia influence the reduced PTH response to hypocalcemia after hypercalcemia. In addition, the implication of the arachidonic acid (AA) signaling pathway in this effect is evaluated. The PTH response to hypocalcemia has been studied in a control group and in four groups of rabbits subjected to hypercalcemia for different periods of time (between 30 and 120 min) and at two levels of hypercalcemia (1 x 9 and 2 x 1 mM). AA levels have been measured in parathyroid glands from rabbits subjected to hyper- and hypocalcemia. When compared with controls, rabbits that had been hypercalcemic (2 x 1 mM) for 2 h showed a markedly attenuated PTH response to hypocalcemia (50% of normal PTHmax), rabbits that had been in hypercalcemia (2 x 1 mM) for 75 min had an intermediate PTH response to hypocalcemia (70% of normal PTHmax) and rabbits that had been subjected to either 30 min hypercalcemia of 2 x 1 mM or 120 min hypercalcemia of 1 x 9 mM had a normal PTH response to hypocalcemia. AA levels increased in hypercalcemia and decreased in hypocalcemia; however, no differences were observed at either calcium level in short-time (30 min) versus long-time (120 min) hypercalcemia. In conclusion, the attenuated PTH response to hypocalcemia after hypercalcemia is dependent on both the period of time that the parathyroid glands have been exposed to hypercalcemia and the degree of hypercalcemia. In addition, this reduced PTH response does not seem to be related to changes in the AA signaling pathway.
S Bas; A Bas; Y Almadén; E Ballesteros; M Rodríguez; E Aguilera-Tejero
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of endocrinology     Volume:  177     ISSN:  0022-0795     ISO Abbreviation:  J. Endocrinol.     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-04-16     Completed Date:  2003-06-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375363     Medline TA:  J Endocrinol     Country:  England    
Other Details:
Languages:  eng     Pagination:  119-26     Citation Subset:  IM    
Departamento de la Medicina y Cirugía Animal, Universidad de Córdoba, Campus de Rabanales, Ctra Madrid-Cádiz km 396, Spain.
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MeSH Terms
Arachidonic Acids / metabolism
Calcium / metabolism
Hypercalcemia / physiopathology*
Hypocalcemia / physiopathology
Parathyroid Hormone / secretion*
Signal Transduction / physiology*
Time Factors
Reg. No./Substance:
0/Arachidonic Acids; 0/Parathyroid Hormone; 7440-70-2/Calcium

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