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This Article Full Text Full Text (PDF) All Versions of this Article: 293/2/R701    most recent 00232.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chen, K. Articles by Rose, J. C. Search for Related Content PubMed PubMed Citation Articles by Chen, K. Articles by Rose, J. C.

RENAL HEMODYNAMICS AND CARDIORENAL INTEGRATION

Thyroid hormone replacement normalizes renal renin and angiotensin receptor expression in thyroidectomized fetal sheep

Departments of ¹Obstetrics/Gynecology, ²Physiology/Pharmacology, and the ³Center for Research in Obstetrics and Gynecology; and Wake Forest University School of Medicine, Winston-Salem, North Carolina

Submitted 5 April 2007 ; accepted in final form 3 June 2007

Previous studies have suggested that thyroid hormone influences maturation of the renin-angiotensin system (RAS) and cardiovascular function in the late-gestation fetal sheep. To further examine the importance of thyroid hormone in this regard, we used the technique of thyroidectomy (TX) to remove endogenous thyroid hormone from the circulation and then replaced it with physiological amounts of exogenous thyroxine. We hypothesized that the previously observed changes in RAS activity and cardiovascular function associated with TX would be normalized. TX was performed at 120 days of gestational age (dGA), and control fetuses were sham operated. After 3 days of recovery, TX fetuses were continuously intravenously infused with thyroxine until delivery by cesarean section close to term (around 138 dGA). Immediately before necropsy, fetuses were infused with isoproterenol, and the hemodynamic responses were noted. Thyroid hormone replacement normalized not only plasma triiodothyronine (T3) and thyroxine (T4) levels but also the TX-induced decreases in renal renin mRNA and renal renin content. Renal ANG II subtype receptor expression levels were also normalized for both mRNA and protein. Decreased basal heat rate and systolic blood pressure associated with TX returned to normal following replacement; however, changes in mean blood pressure and isoproterenol-induced changes in mean blood pressure were not altered. These findings demonstrate that replacement of thyroid hormone in hypothyroid sheep fetuses can restore renal ANG II receptor and renin expression and secretion to normal.

fetus; ANG I and II receptors; thyroidectomy; ovine

This article has been cited by other articles:

				L. C. Carey, N. K. Valego, Kai Chen, and J. C. Rose Thyroid Hormone Regulates Renocortical COX-2 and PGE2 Expression in the Late Gestation Fetal Sheep Reproductive Sciences, July 1, 2008; 15(6): 598 - 603. [Abstract] [PDF]