Dimensions of postcapillary venules sensitive to bradykinin and histamine-induced leakage of macromolecules.
Microvascular leakage of macromolecules was studied in the hamster cheek pouch preparation using fluorescein labelled dextran (FITC-dextran 145 Mw = 145,000) as a tracer. When the preparation is superfused with 10(-5) M histamine or 10(-7) M bradykinin the permeability to macromolecules increases exclusively at postcapillary venules. Microinjections of 30-200 picolitres (pl) of 0.1 M histamine and 10(-4) M bradykinin close to arterioles and capillaries caused extravasation from several postcapillary venules at a distance from site of injection but not from arterioles or capillaries. The minimal diameter of the postcapillary venules where leakage occurred was (n = 45) 8.6 +/- 2.6 (S.D.) microM and the maximal diameter was 14.0 +/- 5.3 microM. Histamine and bradykinin caused leakage of macromolecules in postcapillary venules but not in arterioles, capillaries or larger venules even when these were exposed to high local concentrations of these agents.
D000818:Animals; D001160:Arterioles / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology*; D002196:Capillaries / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects*; D006224:Cricetinae; D006632:Histamine / Q000494:pharmacology*; D046911:Macromolecular Substances; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D008856:Microscopy, Fluorescence; D014680:Veins / Q000187:drug effects*; D014699:Venules / Q000187:drug effects*
D046911:Macromolecular Substances; D006632:Histamine; D001920:Bradykinin