Thyroid hormone modulates renin and ANG II receptor expression in fetal sheep.
نویسندگان
چکیده
Fetal renin-angiotensin system (RAS) activity is developmentally regulated, increasing in late gestation toward term. At the same time, fetal hemodynamic parameters change, with blood pressure increasing and heart rate decreasing. During this period, fetal plasma thyroid hormone concentrations also increase significantly. In this study we utilized the technique of thyroidectomy (TX), which removes thyroid hormone from the circulation, to investigate the importance of thyroid hormone on the developmental changes in the RAS (in plasma, kidney, heart, and lung) and hemodynamic regulation in fetal sheep. TX was performed at 120 days of gestational age (dGA), and control fetuses were sham operated. Immediately before necropsy ( approximately 137 dGA), fetuses were infused with isoproterenol and the hemodynamic responses were noted. TX significantly decreased plasma thyroid hormone concentrations and renal renin mRNA and renal active renin levels but did not change fetal plasma active renin levels. TX decreased both angiotensin II receptor subtype 1 (AT1) mRNA and protein levels in kidney and lung but not in the left ventricle. TX also was associated with increased ANG II receptor subtype 2 (AT2) mRNA and protein at the 44-kDa band in kidney, whereas AT2 protein was decreased at the 78-kDa level in kidney and lung tissue only. TX fetuses had significantly lower basal mean arterial blood pressures (MAP) and heart rates than controls. Isoproterenol infusion decreased MAP in TX fetuses. These findings support the hypothesis that thyroid hormone is important in modulating maturation of RAS and cardiovascular function in the late-gestation fetal sheep.
منابع مشابه
Thyroid hormone replacement normalizes renal renin and angiotensin receptor expression in thyroidectomized fetal sheep.
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...
متن کاملRenin-angiotensin system and unilateral ureteral obstruction
Unilateral ureteral obstruction (UUO) is a clinical scenario that leads to obstructive nephropathy. UUO alters the expression of many mediators in the ipsilateral kidney. Renin-angiotensin system (RAS) is involved in UUO. Angiotensin II (Ang II) and angiotensin 1-7 (Ang 1-7) as the main arms of RAS influence kidney function which may alter by UUO. Ang II via Ang II receptor subtypes I (AT1R) ...
متن کاملAngiotensin II infusion to the midgestation ovine fetus: effects on the fetal kidney.
Renal and cardiovascular responses to an intravenous infusion of ANG II (1 microg/h) or saline for 3 days were examined in ovine fetuses at midgestation (75-85 days of gestation, term 150 days). ANG II caused an increase in fetal blood pressure (36 +/- 2 to 44 +/- 3 mmHg) and urine flow rate (8 +/- 2 to a maximum of 18 +/- 6 ml/h). Plasma renin concentrations decreased in ANG II-infused fetuses...
متن کاملRegulation of in vitro renin secretion by ANG II feedback manipulation in vivo in the ovine fetus.
The renin-angiotensin system is critically important to fetal cardiovascular function and organ development. The feedback regulation of renin secretion by ANG II develops early in gestation yet does not linearly progress from fetal life to adulthood. Renin secretion is elevated in late gestation compared with earlier or postnatal time periods, which suggests that some component of the negative ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- American journal of physiology. Regulatory, integrative and comparative physiology
دوره 289 4 شماره
صفحات -
تاریخ انتشار 2005