Ovariectomy aggravated sodium induced hypertension associated with altered platelet intracellular Ca2+ in Dahl rats

Keiichi Otsuka, Yoichi Ohno, Takayuki Sasaki, Hiroshi Yamakawa, Tomoko Hayashida, Taichi Suzawa, Hiromichi Suzuki, Takao Saruta*

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Our purpose was to determine the effect of ovariectomy on intracellular Ca2+ mobilization and platelet aggregation in sodium induced hypertension. At the age of 12 weeks ovariectomy or sham operation was performed in female Dahl-Iwai salt sensitive rats on a 0.3% NaCl diet. Four weeks later we assessed the effects of ovariectomy and an 8% NaCl diet on agonist induced intracellular Ca2+ mobilization in fura-2 loaded platelets and platelet aggregation. Ovariectomy enhanced the increase of systolic blood pressure and heart to body weight ratio on an 8% NaCl diet. However, thrombin evoked intracellular Ca2+ was not correlated with systolic blood pressure (r = - 0.338, P = .17), and was lowered by sodium loading and ovariectomy (360 ± 23 to 285 ± 9, 296 ± 10 nmol/L, P < .05). Furthermore, the ionomycin induced intracellular calcium fraction in the absence of external Ca2+ that reflected internal Ca2+ discharge capacity was reduced in ovariectomized rats compared with sham operated rats on an 8% NaCl diet (648 ± 15 v 768 ± 35 nmol/L, P < .05). The internal Ca2+ discharge capacity was inversely correlated with systolic blood pressure (r = -0.506, P = .03). In addition to the decreased internal Ca2+ discharge capacity, intracellular Ca2+- independent platelet aggregation by phorbol 12-myristate 13-acetate, a protein kinase C activator, was significantly enhanced in hypertensive rats. We concluded that ovariectomy enhanced sodium induced hypertension associated with the decreased internal Ca2+ discharge capacity and increased platelet aggregation in Dahl-Iwai salt-sensitive rats.

Original languageEnglish (US)
Pages (from-to)1396-1403
Number of pages8
JournalAmerican Journal of Hypertension
Volume10
Issue number12 I
DOIs
StatePublished - Dec 1997

Keywords

  • Calcium
  • Dahl rats
  • Ovariectomy
  • Platelet aggregation
  • Protein kinase C
  • Sodium

ASJC Scopus subject areas

  • Internal Medicine

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