I.: Gastric secretion in relation to mucosal blood flow studied by a clearance technic

There is a considerable body of evidence sug-gesting that secretion and blood flow in the stom-ach vary together (1-6) and an equally impressive array of studies that speaks against such a relation-ship (7-11). In attempting to evaluate a possible relationship between gastric blood flow and secre-tion we are confronted with problems that are basically methodological (12). Nearly all of the investigations cited have been either acute experi-ments on anesthetized and traumatized animals or chronic observations of unanesthetized humans in which nonspecific gastric mucosal changes have been used to gauge gastric blood flow. In the acute experiments both blood flow and secretion are sub-ject to the profound but unmeasured influences of anesthetics and surgical stress, which can camou-flage a relationship. In the chronic studies the color or temperature of the mucosa or the size of microcirculatory vessels has been used as an "in-dex " of mucosal blood flow. Unfortunately these indexes do not measure blood flow: mucosal color and vessel size are estimates of mucosal blood vol-ume, and mucosal temperature reflects deep body temperature, not blood flow. In short, the avail-able evidence on the subject of a relationship be-tween blood flow and secretion in the stomach comes from experiments in which either the state of the preparation or the methods of measuring blood flow was unreliable. We established four requirements that we felt would have to be satisfied for a study of gastric secretory and circulatory function to yield infor