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from Brown Corpus
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The presence of normally occurring bronchial artery-pulmonary artery anastomoses was first noted in 1721 by Ruysch, and thereafter by many others.
Nakamura ( '58 ), Verloop ( '48 ), Marchand, Gilroy and Watson ( '50 ), Von Hayek ( '53 ), and Tobin ( '52 ) have all claimed their normal but relatively nonfunctional existence in the human being.
Miller ( '50 ) is the principal antagonist of this viewpoint.
In criticism of the latter's views, his conclusions were based upon dog lung injection studies in which all of the vascular channels were first filled with a solution under pressure and then were injected with various sized colored particles designed to stop at the arteriolar level.
As early as 1913 Ghoreyeb and Karsner demonstrated with perfusion studies in dogs that bronchial artery flow would remain constant at a certain low level when pressure was maintained in the pulmonary artery and vein, but that increases in bronchial artery flow would occur in response to a relative drop in pulmonary artery pressure.
Berry, Brailsford and Daly in 1931 and Nakamura in 1958 reaffirmed this.
Our own studies in which bronchial artery-pulmonary artery anastomoses were demonstrated, were accomplished by injecting the bronchial artery first with no pressure on the pulmonary artery or vein, and then by injecting the pulmonary artery and vein afterwards.
It is distinctly possible, therefore, that simultaneous pressures in all three vessels would have rendered the shunts inoperable and hence, uninjectable.
This viewpoint is further supported by Verloop's ( '48 ) demonstration of thickened bronchial artery and arteriolar muscular coats which are capable of acting as valves.
In other words, the anastomoses between the bronchial artery and pulmonary artery should be considered as functional or demand shunts.

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