title: Trapping, nontrapping, and release of nine and fifteen micron spheres in dog kidneys.
abstract: Variations in the distribution of different size microspheres trapped within an organ depend upon regional variations in delivery or trapping of different size spheres. We have determined the intrarenal distribution of trapped 9 mu and 15 mu spheres, as well as their nontrapping and release in dog kidneys. More 15 mu spheres than 9 mu spheres are normally trapped in the outer cortex, and fewer 15 mu spheres than 9 mu spheres in the medulla. This is true whether the renal blood flow enters the organ through the hilum or through capsular collaterals with chronic renal artery occlusion. The differences in distribution are due to greater trapping of 15 mu spheres than 9 mu spheres in the outer cortex with subsequent greater delivery and trapping of 9 mu spheres than 15 mu spheres in the vasa rectae of the medulla. Axial migration of the larger 15m spheres with greater distribution to terminal branches of a vessel and less distribution to proximal branches does not explain these observations, because it is independent of the transcortical direction of blood flows. Studies with adenosine triphosphate (ATP) vasodilation show that 15 mu spheres are trapped to a greater degree than 9 mu spheres and that previously trapped 9 mu spheres may be released with ATP vasodilation. Nontrapping and release of microspheres are potential sources of error and are greater with 9 mu than 15 mu spheres.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D004285:Dogs; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects; D007672:Kidney Cortex / Q000098:blood supply; D007679:Kidney Medulla / Q000098:blood supply; D008863:Microspheres; D011859:Radiography; D012039:Regional Blood Flow / Q000187:drug effects; D012077:Renal Artery / Q000000981:diagnostic imaging; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000255:Adenosine Triphosphate