ANTIHISTAMINERGIC PRETREATMENT PREVENTS TISSUE EXTRAVASATION OF ALBUMIN FROM INTRAABDOMINAL TRAUMA IN RATS

Intra-abdominal surgery causes a loss of plasma into tissues within an d around the abdomen, endangering tissue viability. Mast cells, contai ning histamine, are abundant in the abdominal cavity. In a model of me chanical intra-abdominal trauma, we investigated whether pretreatment with histaminergic H-1 and H-2 receptor blockers counteracts this extr avasation. In Wistar rats under chloralose anaesthesia, tissue clearan ces of labelled albumin were determined by a double isotope technique. Four groups were studied: Traumatized rats, pretreated (n=10) and non -pretreated (n=9): non-traumatized rats; pretreated (n=10) and nonpret reated (n=9). In the traumatized rats, given pyrilamine 10 mg kg(-1) ( H-1) plus cimetidine 25 mg kg(-1) (H-2) just before the trauma, the bl ockers prevented the haemoconcentration from loss of plasma and the dr op in arterial pressure during the very trauma procedure, observed amo ng non-pretreated rats. Furthermore, they significantly decreased the clearance of albumin in the abdominal wail and the pancreas. In the no ntraumatized animals, the blockers lowered arterial pressure and heart rate. In conclusion, the anti-histaminergic pretreatment decreased th e trauma induced leakage of albumin, by mechanisms which may involve r eadjustments of pressures and flows in capillaries as well as a preven tion of histamine effects on capillary permeability.