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Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats.

Publication ,  Journal Article
Lobaugh, B; Garner, SC; Lovdal, JA; Boass, A; Toverud, SU
Published in: Am J Physiol
June 1993

Serum ionized calcium (Ca), but not inorganic phosphorus or immunoreactive parathyroid hormone, negatively correlates with renal 25-hydroxyvitamin D-1 alpha-hydroxylase (1 alpha-hydroxylase) and serum 1,25-dihydroxyvitamin D in intact lactating rats. The present study tested the hypothesis that the presumed stimulation of renal 1 alpha-hydroxylase by hypocalcemia requires the presence of intact parathyroid glands. Lactating and nonlactating rats were surgically parathyroidectomized (PTX) or sham-operated (sham) at 9-10 days of lactation. Later (24 h) the rats were bled, nephrectomized, and killed. In lactating PTX rats, serum ionized Ca decreased to 50% of the level of sham rats, and serum 1,25-dihydroxyvitamin D fell to 37 +/- 5.0 pg/ml compared with 82 +/- 13.0 pg/ml for sham lactating rats but was still 2.5 times the value for nonlactating PTX rats (15 +/- 0.8 pg/ml). In contrast to the still elevated serum 1,25-dihydroxyvitamin D concentration in lactating PTX rats, renal 1 alpha-hydroxylase was suppressed to the same low level as in nonlactating PTX rats, suggesting the existence of extrarenal synthesis of 1,25-dihydroxyvitamin D in lactation. A curvilinear relationship was revealed between serum ionized Ca and renal 1 alpha-hydroxylase in sham lactating and nonlactating rats (r2 = 0.71, P < 0.0001). However, in PTX rats, decreasing ionized Ca did not lead to any increase in 1 alpha-hydroxylase above the low baseline values seen at ionized Ca concentrations between 1.3 and 1.5 mM. We therefore conclude that intact parathyroid glands are required for hypocalcemia to activate renal 1 alpha-hydroxylase in female rats.

Duke Scholars

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

June 1993

Volume

264

Issue

6 Pt 1

Start / End Page

E981 / E985

Location

United States

Related Subject Headings

  • Rats, Inbred Strains
  • Rats
  • Parathyroidectomy
  • Lactation
  • Kidney
  • Hypocalcemia
  • Female
  • Dihydroxycholecalciferols
  • Cardiovascular System & Hematology
  • Animals
 

Citation

APA
Chicago
ICMJE
MLA
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Lobaugh, B., Garner, S. C., Lovdal, J. A., Boass, A., & Toverud, S. U. (1993). Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats. Am J Physiol, 264(6 Pt 1), E981–E985. https://doi.org/10.1152/ajpendo.1993.264.6.E981
Lobaugh, B., S. C. Garner, J. A. Lovdal, A. Boass, and S. U. Toverud. “Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats.Am J Physiol 264, no. 6 Pt 1 (June 1993): E981–85. https://doi.org/10.1152/ajpendo.1993.264.6.E981.
Lobaugh B, Garner SC, Lovdal JA, Boass A, Toverud SU. Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats. Am J Physiol. 1993 Jun;264(6 Pt 1):E981–5.
Lobaugh, B., et al. “Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats.Am J Physiol, vol. 264, no. 6 Pt 1, June 1993, pp. E981–85. Pubmed, doi:10.1152/ajpendo.1993.264.6.E981.
Lobaugh B, Garner SC, Lovdal JA, Boass A, Toverud SU. Parathyroidectomy abolishes the increase of renal 25-hydroxyvitamin D-1 alpha-hydroxylase in lactating rats. Am J Physiol. 1993 Jun;264(6 Pt 1):E981–E985.

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

June 1993

Volume

264

Issue

6 Pt 1

Start / End Page

E981 / E985

Location

United States

Related Subject Headings

  • Rats, Inbred Strains
  • Rats
  • Parathyroidectomy
  • Lactation
  • Kidney
  • Hypocalcemia
  • Female
  • Dihydroxycholecalciferols
  • Cardiovascular System & Hematology
  • Animals