The effect of lysine acetylsalicylate on joint capsule mechanoreceptors in rats with polyarthritis.

Joint capsule mechanoreceptors in arthritic rats are more sensitive to pressure than similar receptors in normal animals. This greater sensitivity was reversed by the intravenous or topical administration of lysine acetylsalicylate in anaesthetised rats in doses of 15 to 50 mgm ASA-equivalent/kg. The reduction in sensitivity began within 5-10 min and reached a minimum mean value of 35% of the control after 35 to 40 min. During this period there was a negative linear or exponential relation between the amplitude of response to a controlled mechanical stimulus and time after administration of lysine acetylsalicylate. Control values of sensitivity were reached about 65-70 min following treatment with lysine acetylsalicylate. The results are interpreted as indicating that the high sensitivity of the arthritic joint capsule receptors is due to locally produced prostaglandins, such as prostacyclin.