PLATELET ACTIVATION AND SEROTONIN RELEASE DURING COLORECTAL SURGERY

In vitro studies show serotonin has a profound vasospastic effect on h uman mesenteric arteries. A similar response has peen shown in vivo in atherosclerotic primates. If platelet serotonin stores are released a s a consequence of platelet activation during colorectal surgery, a si milar effect may significantly alter the perfusion of newly formed ana stomoses leading to ischaemia and anastomotic breakdown. Here we have studied the effects of surgery and anaesthesia on intraplatelet and pl asma serotonin levels during the peri- and postoperative period follow ing colorectal surgery. A series of six consecutive patients undergoin g colorectal resection and anastomosis were selected. Peripheral venou s blood samples, taken at specified times before and after surgery and prepared in a platelet stabilizing buffer solution, were analysed usi ng a validated enzyme immunoassay technique. Intraplatelet serotonin l evels were seen to fall post-operatively, whilst plasma serotonin leve ls were shown to rise, implying significant platelet activation and se rotonin during the peri-operative period. This study demonstrates the increased bioavailability of serotonin during the peri-operative perio d in colorectal surgery patients. If the in vitro effects of this amin e are mirrored in vivo, increased plasma levels of serotonin may have an important role in anastomotic dehiscence secondary to ischaemia.