INTESTINAL ALKALINE PHOSPHATASE

Abstract

Although studies have indicated that the gut lipid absorptive capacity is impaired after trauma and hemorrhagic shock, the mechanism responsible for this remains unknown. The aim of this study, therefore, was to determine whether intestinal alkaline phosphatase (IAP) plays any role in the depressed gut lipid absorptive function observed under such conditions. To determine this, 5 cm midline laparotomy (i.e., trauma induced) was performed in the rats, and animals were then bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of shed blood volume was returned in the form of Ringer's lactate. The rats were resuscitated with four times the volume of maximal bleedout with Ringer's lactate over 60 min. For in vivo lipid loading test, 1 mL olive oil was given intraduodenally upon the completion of resuscitation. The enterocytes were isolated at either 0, 1.5, or 5 h after fat feeding, and the soluble, membranous and pre-chylomicron (pre-CM) IAP activities as well as triglyceride contents were determined thereafter. The results indicated that the soluble IAP activity in the villus tip cells isolated from trauma-hemorrhaged rats increased significantly at 0, 1.5, or 5 h after fat feeding. The pre-CMIAP activity, however, decreased markedly in villus tip cells at 1.5 or 5 h after lipid administration, which was associated with the decreased pre-CM triglyceride contents in villus tip cells under such conditions. The altered IAP activity in villus tip cells, therefore, appears to play a role in the depressed gut lipid absorption and transport following trauma-hemorrhage and resuscitation.