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Adrenergic agonists recruit intrapulmonary shunt pathways without exercise or hypoxia
Author(s) -
Jacobson Joseph Elmer,
Bates Melissa L,
Akins Tiffany L,
Diffee Gary M,
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.1102.9
Subject(s) - phenylephrine , medicine , sympathetic nervous system , hypoxia (environmental) , clonidine , adrenergic , saline , endocrinology , adrenergic receptor , receptor , anesthesia , chemistry , blood pressure , organic chemistry , oxygen
Using an intact rat model we studied the role of alpha and beta adrenergic agonists in recruiting intrapulmonary arteriovenous anastamoses (IPAVs). Exercise and hypoxia, which recruit IPAVs, activate the sympathetic nervous system. We hypothesized that IPAV recruitment is regulated by sympathetic mediators. Isoproterenol (2mcg/kg/mL), phenylephrine and clonidine (5 mcg/kg/mL), or saline were infused through a right ventricular catheter in randomized order. One million 15 μm fluorescent microspheres were injected into the superior vena cava, using a different color sphere for each condition. The spleen, kidneys, brain, and liver were harvested and the transpulmonary passage of microspheres measured. Increased microsphere passage was seen in 5/5 rats with both isoproterenol (180±61 v 8±5, p=0.048) and phenylephrine plus clonidine (90±37 v 8±5, p=0.09) compared to the saline control. There appears to be a distinct role of each in regulating the IPAV recruitment. Alpha and beta agonists may act on different vessels to independently recruit IPAVs. Further studies, where adrenergic receptors are blocked and the rats are exercised or experience hypoxia, are necessary for determining whether the sympathetic nervous system plays a direct role in recruiting IPAVs during hypoxia and exercise. This research is funded by the National Institutes of Health (5R01HL086897‐03).