Calcium Balance and Parathyroid Hormone Mediated Vasodilation in the Spontaneously Hypertensive Rat

Sharon Anderson, James R. Grady, David Ellison, David A. McCarron

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The spontaneously hypertensive rat (SHR) exhibits multiple abnormalities of calcium metabolism. Parathyroid hormone (PTH) has been shown to be a potent vasodilator in the SHR as well as other animal species. The current study assessed the influence of short-term manipulation of Ca2 + balance on PTH-induced vasodilation in the SHR. At 16 weeks of age, seven male SHRs were placed on a 0.02% Ca2+(deficient) diet, and eight SHRs were fed a 4% Ca2+(supplemented) diet. Before and 2 weeks after the diet switch, blood and urine samples were obtained. Immediately thereafter, the SHRs received graded, bolus intravenous infusions of human (h)PTH 1-34 (0.1 to 100 μg/kg), and arterial pressure was monitored. The 4% SHR's serum total Ca2+rose (p <0.001) but its serum ionized Ca2+was unchanged. Urinary Ca (UCa) increased (p <0.005), and urinary cAMP declined (p <0.05) in the 4% SHR. The 0.02% SHR's serum total and ionized Ca2 + were unchanged while their UClV actually increased (p <0.05) and their urinary cAMP increased (p <0.01). Both the 4% and 0.02% SHRs exhibited log-dose dependent (p <0.001) depressor responses to hPTH 1-34. The 4% SHR, however, demonstrated greater (p <0.01) sensitivity to and prolongation of (p <0.01) this hypotensive action of PTH. We conclude that PTH is a potent depressor peptide in the SHR. Modification of Ca2+balance in the SHR will alter the dose response curve to PTH-induced vasodilation. Alterations in cellular Ca2+but not necessarily extracellular Ca2+appear to be functionally important in determining the vascular effects of hPTH 1-34.

Original languageEnglish (US)
Pages (from-to)I-59-I-63
JournalHypertension
Volume5
Issue number2
StatePublished - 1983

Fingerprint

Inbred SHR Rats
Parathyroid Hormone
Vasodilation
Calcium
Teriparatide
Diet
Serum
Multiple Abnormalities
Vasodilator Agents
Intravenous Infusions
Blood Vessels
Arterial Pressure
Urine
Peptides

Keywords

  • Calcium balance vasodilation
  • Hormone
  • Hypertensive rat
  • Parathyroid
  • Spontaneously

ASJC Scopus subject areas

  • Internal Medicine

Cite this

Calcium Balance and Parathyroid Hormone Mediated Vasodilation in the Spontaneously Hypertensive Rat. / Anderson, Sharon; Grady, James R.; Ellison, David; McCarron, David A.

In: Hypertension, Vol. 5, No. 2, 1983, p. I-59-I-63.

Research output: Contribution to journalArticle

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abstract = "The spontaneously hypertensive rat (SHR) exhibits multiple abnormalities of calcium metabolism. Parathyroid hormone (PTH) has been shown to be a potent vasodilator in the SHR as well as other animal species. The current study assessed the influence of short-term manipulation of Ca2 + balance on PTH-induced vasodilation in the SHR. At 16 weeks of age, seven male SHRs were placed on a 0.02{\%} Ca2+(deficient) diet, and eight SHRs were fed a 4{\%} Ca2+(supplemented) diet. Before and 2 weeks after the diet switch, blood and urine samples were obtained. Immediately thereafter, the SHRs received graded, bolus intravenous infusions of human (h)PTH 1-34 (0.1 to 100 μg/kg), and arterial pressure was monitored. The 4{\%} SHR's serum total Ca2+rose (p <0.001) but its serum ionized Ca2+was unchanged. Urinary Ca (UCa) increased (p <0.005), and urinary cAMP declined (p <0.05) in the 4{\%} SHR. The 0.02{\%} SHR's serum total and ionized Ca2 + were unchanged while their UClV actually increased (p <0.05) and their urinary cAMP increased (p <0.01). Both the 4{\%} and 0.02{\%} SHRs exhibited log-dose dependent (p <0.001) depressor responses to hPTH 1-34. The 4{\%} SHR, however, demonstrated greater (p <0.01) sensitivity to and prolongation of (p <0.01) this hypotensive action of PTH. We conclude that PTH is a potent depressor peptide in the SHR. Modification of Ca2+balance in the SHR will alter the dose response curve to PTH-induced vasodilation. Alterations in cellular Ca2+but not necessarily extracellular Ca2+appear to be functionally important in determining the vascular effects of hPTH 1-34.",
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