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Intrapulmonary Shunt Pathways Are Recruited By Hypoxia and Beta Agonists in Juvenile Swine
Author(s) -
Bates Melissa L.,
Jacobson Joseph E.,
Sobakin Aleksey S.,
Hacker Timothy A.,
Eldridge Marlowe W.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.660.9
Subject(s) - juvenile , hypoxia (environmental) , shunt (medical) , medicine , cardiology , chemistry , biology , genetics , organic chemistry , oxygen
Large diameter intrapulmonary venous anastomoses (IPAVs) connect arteries and veins, bypassing the capillary bed. We have speculated that these may be remnant fetal shunt pathways and hypothesized that they would be more abundant in younger animals. We exposed three and six week old piglets to 21% and 8% O 2 . We then performed saline contrast bubble echocardiography and injected 15 μm fluorescent microspheres into the pulmonary artery and left ventricle to quantify the shunt fraction. The brain was removed, hydrolyzed, and the number of microspheres quantified. We found no evidence of bubble contrast or microsphere passage with 21% O 2 , but positive contrast in 6/8 and microspheres in 8/8. Furthermore, the shunt fraction tended to be higher in the three week old piglets (3.3±1.2 vs 0.6±0.1). These data suggest that IPAVs are less abundant or harder to recruit with advancing age. In a single piglet, we perfused 5 μg/kg/hr isoproterenol to investigate whether beta agonists recruit IPAVs. Saline contrast echocardiography was positive with isoproterenol, but negative when the piglet was given 100% O 2 . This suggests that beta adrenergic activation and oxygen tension are important modulators of IPAV recruitment in early life. In future studies we plan to investigate whether beta receptor activation is necessary for IPAV recruitment in hypoxia. This research is funded by NIH 5R01HL086897‐03 and AHA 10POST25000265.