Liver blood flow during haemorrhagic shock in the dog treated with phenoxybenzamine.

The liver blood flow has been extensively studied in hemorrhagic shock, but considerable disagreement exists as to the nature of hemodynamic changes and their controlling mechanism. The present investigation was undertaken in order to determine the effects of hemorrhage and phenoxybenzamine (PBZ) on the participation of hepatic artery (HAF) and portal vein flow (PVF) in total liver blood flow (LBF) changes. The dynamics of LBF (H2 washout method), HAF and PVF (electromagnetic flowmeter) during 3-hours posthemorrhagic hypotension (90 min. = 50-60 mmHg; 90 min. = 25-30 mmHg) and one-hour postretransfusion period were investigated on 20 mongrel dogs under chloralose anesthesia. All animals were divided into 2 groups (control and PBZ-treated--5 mg/kg b.w. 30 minutes following first bleeding). Half an hour following bleeding there occurred a significant decrease of LBF (P less than 0.001) in dogs of both experimental groups. This degree of decrease was due to equal decrease in the PVF and HAF. The infusion of PBZ caused a slight tendency towards increase of LBF, while the subsequent decrease in blood flow values during second hypotensive period in the treated dogs was not so pronounced as in the untreated dogs. Although retransfusion led to an increase of LBF, HAF and PVF in both groups, the restauration was significantly better in PBZ-treated animals. The degree of metabolic acidosis was more pronounced in the untreated dogs than in PBZ-treated.