ISSN:
1420-908X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract PAF-acether is a potent aggregating agent released by various cells involved in acute inflammatory process. In this paper, exogenous PAF-acether has been investigated for its ability to generate signs of inflammation (edema measured by plethysmometry) and hyperalgesia (Randall-Sellito test) by standard subplantar injection in the rat paw. From 0.005 μg, PAF-acether induced significant edema of the paw, maximal 1 hour after injection; it was dose-dependent from 0.1 to 5 μg. Significant dose-dependent hyperalgesia occurred from 1.25 μg; it reached a plateau from 2 to 4 hours after injection. Both phenomena were long-lasting (〉6 h). PAF-acether was 1.5 to 10 times stronger than PGI2 and PGE2 in inducing edema, pain, and in increasing vascular permeability. We investigated the interaction of miscellaneous drugs with the edema and the hyperalgesia caused by 2.5 μg of PAF-acether. Non-steroidal anti-inflammatory (NSAI) drugs exerted only moderate effects on the edema without affecting hyperalgesia. Edema was highly reduced by various agents: prednisolone,l-cysteine, anti-calcic drugs, theophylline, PGI2, salbutamol, clonidine. All of them, except clonidine, and in contrast to NSAI drugs, were more potent on PAF-acether edema than on kaolin edema; a possible link between these agents is their ability to increase cyclic AMP levels in the cells and consequently to reduce lysosomal enzyme release. PAF-acether itself, injected intra-peritoneally, inhibited PAF-acether edema without preventing pain, at doses inactive on arterial pressure and hematocrit, but inducing marked gastric mucosal damage. Among the drugs tested, including analgesics, only PGI2 and imidazole improved PAF-induced hyperalgesia, showing a dissociation between edema and hyperalgesia not only in their induction (doses of PAF required, time course of the phenomena), but in the drugs able to antagonize their development too.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01978740
