HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 106/6/1986    most recent 01357.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Lovering, A. T. Articles by Eldridge, M. W. PubMed PubMed Citation Articles by Lovering, A. T. Articles by Eldridge, M. W.

Transpulmonary passage of ^99mTc macroaggregated albumin in healthy humans at rest and during maximal exercise

¹John Rankin Laboratory of Pulmonary Medicine, Departments of ²Pediatrics and ³Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin

Submitted 20 December 2007 ; accepted in final form 10 April 2009

We have demonstrated that 50-µm-diameter arteriovenous pathways exist in isolated, healthy human and baboon lungs, ventilated and perfused under physiological pressures. These findings have been confirmed and extended by demonstrating the passage of 25-µm microspheres through the lungs of exercising dogs, but not at rest. Determination of blood flow through these large-diameter intrapulmonary arteriovenous pathways would be an important first step to establish a physiological role for these vessels. Currently, we sought to estimate blood flow through these arteriovenous pathways using technetium-99m (^99mTc)-labeled macroaggregated albumin (MAA) in healthy humans at rest and during maximal treadmill exercise. We hypothesized that the percentage of ^99mTc MAA able to traverse the pulmonary circulation (%transpulmonary passage) would increase during exercise. Seven male subjects without patent foramen ovale were injected with ^99mTc MAA at rest on 1 day and during maximal treadmill exercise on a separate day (>6 days). Within 5 min after injection, subjects began whole body imaging in the supine position. Six of the seven subjects showed an increase in transpulmonary passage of MAA with maximal exercise. Using two separate analysis methods, percent transpulmonary passage significantly increased with exercise from baseline to absolute values of 1.2 ± 0.8% (P = 0.008) and 1.3 ± 1.0% (P = 0.016), respectively (means ± SD; paired t-test). We conclude that MAA may be traversing the pulmonary circulation via large-diameter intrapulmonary arteriovenous conduits in healthy humans during exercise. Recruitment of these pathways may divert blood flow away from pulmonary capillaries during exercise and compromise the lung's function as a biological filter.

lung; contrast echocardiography; cryptogenic stroke; pulmonary gas exchange

This article has been cited by other articles:

				R. L. Jones, A. W. Sheel, R. Naeije, J. M. B. Hughes, and M. L. Bates Pathophysiological insight into shunted bubbles. J Appl Physiol, September 1, 2009; 107(3): 999 - 1000. [Full Text] [PDF]

				S. R. Hopkins, I. M. Olfert, and P. D. Wagner Last Word on Point:Counterpoint: Exercise-induced intrapulmonary shunting is imaginary vs. real J Appl Physiol, September 1, 2009; 107(3): 1002 - 1002. [Full Text] [PDF]

				A. T. Lovering, M. W. Eldridge, and M. K. Stickland Last Word on Point:Counterpoint: Exercise-induced intrapulmonary shunting is imaginary vs. real J Appl Physiol, September 1, 2009; 107(3): 1003 - 1003. [Full Text] [PDF]