Experimental thermal lesions induce beta-thromboglobulin release from activated platelets

Time courses of beta-thromboglobulin release, and protein extravasation after thermal inflammation of human skin was compared to neurogenic inflammation induced by histamine iontophoresis. Beta-TG and protein levels were sampled by intradermal microdialysis. Three microdialysis membranes were inserted at each stimulation site. The collected samples were measured photometrically for protein by the Coomassie blue method and for beta-TG by ELISA. Heat stimuli of 40°C and 47°C, and histamine iontophoresis were inflicted directly above the membranes. In vitro recovery rates of beta-TG and bovine albumin were measured using a latex chamber. Recovery rates at a continuous flow rate of 3 μl/min for bovine albumin ranged between 20% and 35%; those for beta-TG ranged between 14% and 17%. Heat stimulation at 40°C showed a slight but insignificant increase of beta-TG during the stimulation period. Temperatures of 47°C produced a significant, long-lasting increase of beta-TG, whereas histamine iontophoresis did not. Protein extravasation corresponded with beta-TG release; a long-lasting significant increase during and after the burn lesion, and only an initial increase of protein extravasation during the 40°C heat stimulus. Long lasting heat stimuli to the skin induced beta-TG release from platelets, whereas histamine iontophoresis although provoking protein extravasation and neurogenic flare, did not. Using microdialysis techniques we detected beta-TG release during an inflammatory response. We conclude that local platelet activation is induced by the heating stimulus. Platelet mediators, such as beta-TG might contribute to the subsequent inflammatory process which is also characterized by mechanical and heat hyperalgesia.