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Newborn lamb coronary artery reactivity is programmed by early gestation dexamethasone before the onset of systemic hypertension
Journal article   Open access   Peer reviewed

Newborn lamb coronary artery reactivity is programmed by early gestation dexamethasone before the onset of systemic hypertension

Robert D Roghair, Jeffrey L Segar, Ram V Sharma, Matthew C Zimmerman, D K Jagadeesha, Emily M Segar, Thomas D Scholz and Fred S Lamb
American journal of physiology. Regulatory, integrative and comparative physiology, Vol.289(4), pp.R1169-1176
10/2005
DOI: 10.1152/ajpregu.00369.2005
PMCID: PMC2730218
PMID: 15961529
url
https://doi.org/10.1152/ajpregu.00369.2005View
Published (Version of record) Open Access

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.
 Pregnancy Animals, Newborn Coronary Vessels - drug effects Prenatal Exposure Delayed Effects Dexamethasone - administration & dosage Hypertension - congenital Coronary Vessels - physiopathology Disease Susceptibility - physiopathology Coronary Vessels - embryology Dexamethasone - adverse effects Disease Susceptibility - chemically induced Gestational Age Animals Hypertension - embryology Disease Susceptibility - embryology Hypertension - chemically induced Maternal Exposure - adverse effects Female Sheep

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