Increased microvascular permeability in the hamster cheek pouch induced by oxidized low density lipoprotein (oxLDL) and some fragmented apolipoprotein B proteins.
OBJECTIVE
Oxidized low-density lipoproteins (oxLDL) and protein fractions obtained by size exclusion chromatography of oxLDL were tested for vascular permeability effects on topical application to the hamster cheek pouch.


METHODS
The hamster cheek pouch was prepared for intravital microscopy observations of macromolecular leakage at post capillary venules (=leaks) with FITC-dextran as tracer.


METHODS
OxLDL (0.1 mg/ml), PAF (platelet activation factor, 50-100 nM) and protein fractions of oxLDL (10 microg/ml) were applied topically to hamster cheek pouches.


RESULTS
Application of oxLDL and PAF resulted in reversible increases in the number of leaks. The PAF-antagonist WEB 2170, L-NAME and a beta(2)-adrenoceptor agonist inhibited (P<0.01) almost completely the macromolecular leakage induced with oxLDL or PAF. Protein fractions were found to be more effective than unfractionated oxLDL in inducing plasma leakage as calculated on mg/ml-basis.


CONCLUSIONS
Hamster oxLDL is a potent inducer of macromolecular leakage increase in the hamster cheek pouch microcirculation. The principal effect is mediated by PAF-like structures produced by the oxidation of the LDL-particle but oxLDL also contains low molecular weight proteins that could contribute to the overall vascular permeability increasing effect of ox LDL.
Svensjö
E
E
Laboratório de Imunologia Molecular, Instituto Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro. eriksvensjo@aol.com
Boschcov
P
P
Ketelhuth
D F J
DF
Jancar
S
S
Gidlund
M
M
D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001055:Apolipoproteins B / Q000494:pharmacology*; D002199:Capillary Permeability / Q000187:drug effects*; D002610:Cheek / Q000098:blood supply / Q000502:physiology; D002850:Chromatography, Gel; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D008647:Mesocricetus; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000819:agonists; D043562:Receptors, G-Protein-Coupled / Q000819:agonists; D013726:Terbutaline / Q000494:pharmacology
D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D001055:Apolipoproteins B; D004791:Enzyme Inhibitors; D008077:Lipoproteins, LDL; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C099252:oxidized low density lipoprotein; C039351:platelet activating factor receptor; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D013726:Terbutaline; D019331:NG-Nitroarginine Methyl Ester