Abstract
Summary
To determine if the fall in serum alkaline phosphatase (SAP) in rats after whole-body or abdominal X-irradiation was due largely to decreased ability to produce intestinal alkaline phosphatase (IAP), young adult male Sprague-Dawley rats were exposed to 800 R whole-body or regional irradiation. Determinations were made of SAP with or without the addition of L-phenylalanine. The reduction in value of SAP by this inhibitor was used to indicate the relative amount of IAP contributed to the serum. Administration of olive oil by stomach tube, which stimulates production of IAP, caused a sharp rise in the L-phenylalanine-inhibited fraction of SAP in normal starved rats, but virtually no rise 4 days after whole-body or abdominal irradiation. Shielding the abdomen or its upper or middle portions during irradiation gave fairly complete protection and permitted a normal response to olive oil, while shielding the lower abdomen or duodenum gave only slight to moderate protection. Irradiating the entire abdomen or the midportion gave the same effect as whole-body irradiation, while irradiating the upper or the lower abdomen or duodenum caused a moderate suppression of the normal response to olive oil. These findings indicate that injury to the duodenum and journal mucosa is mainly responsible for the fall in IAP in the serum following irradiation and that the injury is sufficient to diminish or prevent synthesis of intestinal aklaline phosphatase even after stimulation by olive oil. This appears to be due primarily to a reduced population of differentiated cells lining the villi.
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