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Effects of gestational age on myocardial blood flow and coronary flow reserve in pressure-loaded ovine fetal hearts. Am J Physiol Heart Circ Physiol 2002 Apr;282(4):H1359-69

Date

03/15/2002

Pubmed ID

11893572

DOI

10.1152/ajpheart.00686.2001

Scopus ID

2-s2.0-0036081425   15 Citations

Abstract

To test the hypothesis that coronary flow and coronary flow reserve are developmentally regulated, we used fluorescent microspheres to investigate the effects of acute (6 h) pulmonary artery banding (PAB) on baseline and adenosine-enhanced right (RV) and left ventricular (LV) blood flow in two groups of twin ovine fetuses (100 and 128 days of gestation, term 145 days, n = 6 fetuses/group). Within each group, one fetus underwent PAB to constrict the main pulmonary artery diameter by 50%, and the other twin served as a nonbanded control. Physiological measurements were made 6 h after the surgery was completed; tissues were then harvested for analysis of selected genes that may be involved in the early phase of coronary vascular remodeling. Within each age group, arterial blood gas values, heart rate, and mean arterial blood pressure were similar between control and PAB fetuses. Baseline endocardial blood flow in both ventricles was greater in 100 than 128-day fetuses (RV: 341 +/- 20 vs. 230 +/- 17 ml*min(-1)*100 g(-1); LV: 258 +/- 18 vs. 172 +/- 23 ml*min(-1)*100 g(-1), both P < 0.05). In both age groups, RV and LV endocardial blood flows increased significantly in control animals during adenosine infusion and were greater in PAB compared with control fetuses. After PAB, adenosine further increased RV blood flow in 128-day fetuses (from 416 +/- 30 to 598 +/- 33 ml*min(-1)*g(-1), P < 0.05) but did not enhance blood flow in 100-day animals (490 +/- 59 to 545 +/- 42 ml*min(-1)*100 g(-1), P > 0.2). RV vascular endothelial growth factor and Flk-1 mRNA levels were increased relative to controls (P < 0.05) in 128 but not 100-day PAB fetuses. We conclude that in the ovine fetus, developmentally related differences exist in 1) baseline myocardial blood flows, 2) the adaptive response of myocardial blood flow to acute systolic pressure load, and 3) the responses of selected genes involved in vasculogenesis to increased load in the fetal myocardium.

Author List

Dalshaug GB, Scholz TD, Smith OM, Bedell KA, Caldarone CA, Segar JL

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

Adenosine
Animals
Blood Flow Velocity
Body Weight
Coronary Circulation
Embryonic and Fetal Development
Extracellular Matrix Proteins
Female
Gene Expression Regulation, Developmental
Gestational Age
Heart
Heart Septum
Heart Ventricles
Organ Size
Ovulation
Pregnancy
Pulmonary Artery
Receptor Protein-Tyrosine Kinases
Receptors, Growth Factor
Receptors, Vascular Endothelial Growth Factor
Sheep
Transforming Growth Factor beta
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