Inhibitory effects of BaSO4 on experimentally induced inflammation in the rat mediated by alpha M-foetoprotein.

The influence was studied of BaSO4 (i.p.) pretreatment on the mediator induced inflammatory responses: oedema formation, measured plethysmographically, increased vascular permeability to protein, measured by the extravascular accumulation of 125I-labeled albumin (125I-HSA) and vasodilatation, measured by the accumulation of 51Cr-labeled erythrocytes. Subplantar application of histamine, 5-hydroxytryptamine, bradykinin or prostaglandin E2 caused oedema formation, an enormous 125I-HSA accumulation and a relatively small 51Cr-labeled erythrocytes accumulation. BaSO4 pretreatment inhibited all these inflammatory responses to a high extent, while the alpha M-foetoprotein (alpha MFP) serum levels were increased from a normal value of 188 +/- 123 micrograms/ml up to 5200 +/- 2264 micrograms/ml (n = 29). From this study and previous data using purified alpha MFP it could be assumed that the anti-inflammatory effects induced by BaSO4 pretreatment are mediated by this enormous increase of the alpha MFP serum levels of alpha MFP are nonspecific and possibly caused by a coating and/or membrane stabilizing effect on cell membranes and/or endothelial junctions.