Effects of airway luminal concentration of albumin on histamine-induced mucosal exudation of radio-iodine labelled albumin.
In an in vivo study of guinea-pig airway barriers we have examined the effects of the luminal concentration of albumin on exudation (outward) and absorption (inward) permeabilities to radio-iodine labelled albumin. Previously validated techniques for superfusion of solutes onto the tracheobronchial mucosal surface and for subsequent tracheal lavage were employed. [125I]albumin was administered intravenously as plasma tracer and [131I]albumin was superfused topically as absorption tracer. Histamine (5.0 nmol) was superfused onto the mucosal surface together with the absorption tracer and in the presence of different albumin concentrations (0.3, 3.0 and 30 mg ml-1). The experiment was terminated 10 minutes after the tracheal mucosal superfusion and samples of plasma and tracheal lavage fluid were collected. The mucosal exudation response was calculated from the detection of [125I]albumin in the airway lumen. The absorption ability of the mucosa was determined by the detection of [131I]albumin in circulating plasma. Histamine induced a significant mucosal exudation of [125I]albumin. This effect was unaffected by the level of albumin on the mucosal surface. There was a small but significant absorption of [131I]albumin in the presence of 0.3 and 3.0 mg ml-1 of albumin in the luminal liquid. An albumin concentration of 30 mg ml-1 markedly increased the rate of absorption of [131I]albumin. However, the absorption rate was not affected by the histamine-induced mucosal exudation process at any level of luminal albumin. The present data further demonstrates that plasma exudation and mucosal absorption are independent processes. The data are in keeping with the view that an increased subepithelial hydrostatic pressure moves the plasma exudate across the mucosa as a distinct outward process.
Greiff
L
L
Department of Oto-Rhino-Laryngology, University of Lund, Sweden.
Erjefält
I
I
Pipkorn
U
U
Persson
C G
CG
D000042:Absorption; D000418:Albumins / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D005122:Exudates and Transudates / Q000378:metabolism; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009092:Mucous Membrane / Q000378:metabolism; D012137:Respiratory System / Q000378:metabolism*; D012711:Serum Albumin, Radio-Iodinated; D007507:Therapeutic Irrigation
D000418:Albumins; D012711:Serum Albumin, Radio-Iodinated; D006632:Histamine