Capsaicin pretreatment of rats does not prevent tissue extravasation of albumin from intraabdominal trauma

Intra‐abdominal surgery causes a loss of plasma into tissues within and around the abdomen, predisposing to a decreased tissue viability and postoperative complications. In a rat model of intra‐abdominal trauma, we investigated whether neuropeptides released from thin afferent nerve endings may contribute to this extravasation. Newborn male Wistar rats were pretreated with capsaicin 50 mg/kg s.c., leading to a lifelong degeneration of thin afferents. The same animals, when adult, were subjected to experiments under chloralose anesthesia in which tissue clearances of radiolabelled albumin were determined by a double isotope technique. Non‐pretreated animals served as controls. In non‐traumatized animals, pretreated rats had a higher loss of labelled albumin in calf muscle. In animals subjected to the standardized intra‐abdominal trauma, the pretreatment did not decrease the trauma‐induced loss of albumin. In neck skin, the loss of protein was higher in pretreated animals, possibly due to a decreased trauma‐induced sympathetic activation. In conclusion, degeneration of thin afferent fibers may alter the autonomic reflex response to intra‐abdominal trauma, but neuropeptide release from afferents apparently plays no role in the relocation of albumin.