title: Time-related changes in microsphere entrapment in canine jejunum.
abstract: To assess the validity of repeated blood flow measurements using the microsphere technique, the apparent blood flows in the anatomic layers of the jejunum were determined from the entrapment of 9-, 11.5-, and 17-micron microspheres at 1.5, 15, 30, and 60 min after their injection. The entrapment of 17-micron spheres in the mucosa plus submucosa and in the muscularis propria remained similar at all times, but these spheres migrated (P less than 0.01) from the submucosa to the mucosa. By 1.5 min, 5 +/- 2% of 11.5-micron spheres had shunted, but no subsequent shunting was observed. No migration of 11.5-micron spheres from the mucosa, submucosa or the muscularis was observed. The shunting of 9-micron spheres from the whole wall increased from 19 +/- 4% at 1.5 min to 40 +/- 4% at 60 min (P less than 0.001). These data suggest that 17-micron spheres can only fractionate the blood flow of the whole wall into that of the mucosa plus submucosa and that of the muscularis propria, while 11.5-micron spheres may measure fractional flow to the submucosa separately. The continued washout of 9-micron microspheres precludes their use for repeated blood flow measurements.
authors.affiliation: Department of Medicine, Queen's University, Hotel Deiu Hospital, Kingston, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Prokopiw
authors.forename: P K
authors.initials: PK
authors.lastname: Dinda
authors.forename: I T
authors.initials: IT
authors.lastname: Beck
mesh_terms: D000818:Animals; D004285:Dogs; D007413:Intestinal Mucosa / Q000098:blood supply*; D007583:Jejunum / Q000098:blood supply*; D007700:Kinetics; D008297:Male; D008433:Mathematics; D008722:Methods; D008863:Microspheres; D008962:Models, Theoretical; D012039:Regional Blood Flow; D013997:Time Factors