Measurement of intestinal protein synthesis by continuous arterial tracer application: Intrinsically difficult problems arising from different protein pools and study techniques

True values for protein synthesis in the dominating slow turnover pool will only be obtained, if sequential mucosa enrichments are measured after a plateau has been reached in the rapid turnover pool, and if metabolic manipulations are only started beyond this point. However, this approach precludes the simultaneous registration of metabolic effects in the rapid turnover pool.