title: Hydroxyapatite crystal-induced inflammation and prostaglandin E1.
abstract: Hyroxyapatite (HOAp), tribasic calcium phosphate, crystals induced typical signs of inflammation when injected into the footpad of the rat. Rats deficient in essential fatty acids (EFA) and thereby deficient in prostaglandins (PG) demonstrated less swelling than did normal controls. Similar reduced inflammatory swelling resulted from the use of HOAp crystals heated to 200 degrees C. The reduced inflammogenic effect of the heated crystal and the reduced response of the EFA-deficient rat were comparable and were corrected by adding PGE1. This PGE1 influence was of short duration in both test systems. A new theory of crystal induced inflammation is presented based on experiments using PGE1 with monosodium urate, calcium pyrophosphate and HOAp crystals. It is suggested that this inflammation is a membrane phenomenon related to synthesis or release of PG from cellular membranes stimulated by an electrostatic force from the crystals.
mesh_terms: D000818:Animals; D004032:Diet; D004487:Edema / Q000276:immunology; D006358:Hot Temperature; D006882:Hydroxyapatites / Q000494:pharmacology*; D007249:Inflammation / Q000139:chemically induced / Q000276:immunology*; D011458:Prostaglandins E; D051381:Rats
chemical_list: D006882:Hydroxyapatites; D011458:Prostaglandins E