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Newborn lamb coronary artery reactivity is programmed by early gestation dexamethasone before the onset of systemic hypertension. Am J Physiol Regul Integr Comp Physiol 2005 Oct;289(4):R1169-76

Date

06/18/2005

Pubmed ID

15961529

Pubmed Central ID

PMC2730218

DOI

10.1152/ajpregu.00369.2005

Scopus ID

2-s2.0-25844444648   30 Citations

Abstract

Exposure of the early gestation ovine fetus to exogenous glucocorticoids induces organ-specific alterations in postnatal cardiovascular physiology. To determine whether early gestation corticosteroid exposure alters coronary reactivity before the development of systemic hypertension, dexamethasone (0.28 mg x kg(-1) x day(-1)) was administered to pregnant ewes by intravenous infusion over 48 h beginning at 27 days gestation (term, 145 days). Vascular responsiveness was assessed in endothelium-intact coronary arteries isolated from 1-wk-old steroid-exposed and age-matched control lambs (N = 6). Calcium imaging was performed in fura 2-loaded primary cultures of vascular smooth muscle cells (VSMC) from the harvested coronary arteries. Early gestation steroid exposure did not significantly alter mean arterial blood pressure or coronary reactivity to KCl, thromboxane A(2) mimetic U-46619, or ANG II. Steroid exposure significantly increased coronary artery vasoconstriction to acetylcholine and endothelin-1. Vasodilatation to adenosine, but not nitroprusside or forskolin, was significantly attenuated following early gestation steroid exposure. Endothelin-1 or U-46619 stimulation resulted in a comparable increase in intracellular calcium concentration ([Ca(2+)](i)) in coronary VSMC isolated from either dexamethasone-treated or control animals. However, the ANG II- or KCl-mediated increase in [Ca(2+)](i) in control VSMC was significantly attenuated in VSMC harvested from dexamethasone-treated lambs. Coronary expression of muscle voltage-gated l-type calcium channel alpha-1 subunit protein was not significantly altered by steroid exposure, whereas endothelial nitric oxide synthase expression was attenuated. These findings demonstrate that early gestation glucocorticoid exposure elicits primary alterations in coronary responsiveness before the development of systemic hypertension. Glucocorticoid-induced alterations in coronary physiology may provide a mechanistic link between an adverse intrauterine environment and later cardiovascular disease.

Author List

Roghair RD, Segar JL, Sharma RV, Zimmerman MC, Jagadeesha DK, Segar EM, Scholz TD, Lamb FS

Author

Jeffrey L. Segar MD Professor in the Pediatrics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Animals, Newborn
Coronary Vessels
Dexamethasone
Disease Susceptibility
Female
Gestational Age
Hypertension
Maternal Exposure
Pregnancy
Prenatal Exposure Delayed Effects
Sheep
jenkins-FCD Prod-486 e3098984f26de787f5ecab75090d0a28e7f4f7c0