Effects of indomethacin on plasma fibrinogen levels in rats with tissue injury.

The present investigation was designed to study the effect of indomethacin (5 mg kg-1 day-1) on plasma fibrinogen levels in laparotomized rats. Whereas tissue injury significantly increased plasma fibrinogen when compared to normal uninjured rats, indomethacin completely blocked that effect. Conversely, indomethacin did not prevent fibrinogen increase in laparotomized rats injected with epinephrine, with spinal cord transection + epinephrine or with adrenal medullectomy + epinephrine. Indomethacin or epinephrine administration to normal rats did not modify plasma fibrinogen. Taking into account that epinephrine is a key hormone in plasma fibrinogen response in laparotomized rats, and according to our results, prostaglandins might act by two possible pathways: 1) by decreasing of the pain threshold of the sensory nerve endings and stimulating sympathetic adreno-medullar system; 2) by entering into the blood stream and enhancing epinephrine action on plasma fibrinogen. It would appear that indomethacin inhibits both pathways.