Blood flow through vasa vasorum in arteries and veins: effects of luminal XXXX .

@entity235 @entity519 @entity4095 @entity5333
We have examined effects of chronic reduction of intraluminal @entity4095 on blood flow through vasa vasorum, by comparing large arteries and veins, and effects of acute @entity519 on flow through vasa. Microspheres were used to measure flow in anesthetized @entity235 . Values obtained with different sizes of microspheres suggest that spheres 9 and 15 micron in diam, but not 50 micron, are appropriate for measurement of blood flow through vasa vasorum. Flow [expressed as ml X min-1 X 100 g-1 (SE)] through medial vasa was similar in the aorta (9.0 +/- 2.1) and pulmonary artery (9.3 +/- 1.1) although, on the basis of wall thickness and number of lamellae, one would predict much higher levels of flow to aortic media. Two veins that we studied have a thick muscular wall. Both veins had high levels of flow through medial vasa: 33 +/- 4.4 to the subdiaphragmatic inferior vena cava and 18 +/- 5.4 to the portal vein. Two other veins are apparently conduit vessels, with dense connective tissue and minimal smooth muscle. Both veins had minimal flow through medial vasa: 2.4 +/- 1.0 to superior vena cava, and 1.9 +/- 0.8 to supradiaphragmatic inferior vena cava. Thus, because flow through vasa differs greatly in different veins, structure of the vessel (as well as intraluminal @entity4095 ) is an important determinant of flow through vasa. Acute @entity519 increased conductance of medial vasa vasorum of arteries and veins when neurohumoral constrictor effects were blocked by @entity5333 .(ABSTRACT TRUNCATED AT 250 WORDS)
