SUMMARY1. Chloralose anaesthetized cats were prepared with fundic and antral pouches. Fundic mucosal blood flow was measured by the amidopyrine technique and serum gastrin was measured by radioimmunoassay.2. Meat extract suspension in the pyloric antrum produced a highly significant sixfold increase in arterial serum gastrin concentration (P < 0-001).3. The mean ratio of the fundic mucdsal blood flow to acid secretary responses (AMBF/LAH+ ratio) of 0-142 + 0-026 (25) ml./,uequiv H+, is very similar to the values previously published for exogenous gastrin stimulation. 4. Splanchnic nerve stimulation, during responses to meat extract stimulation, produced significant reductions in gastric acid secretion (P < 0-025), fundic mucosal blood flow (P < 0-02), arterial serum gastrin concentration (P < 0-01) and gastrin delivered to the mucosa (P < 0.001).5. In the 30 min period following the end of splanchnic nerve stimulation only arterial serum gastrin concentration remained significantly reduced.

SUMMARYThe gastric acid secreted per unit of serum gastrin concentration or per unit of gastrin delivered to the gastric mucosa was significantly greater during electrical vagal stimulation than during stimulation by meat extract in the pyloric antrum.There was no significant difference in the concentrations of big, big gastrin or Components I and II in gastric venous serum during the two forms of stimulation.There were significantly greater concentrations of Components II and IV in gastric venous serum during meat extract stimulation than during vagal stimulation.The gastrin in gastric venous serum when meat extract was in the pyloric antrum was comprised of Component IV in addition to Component III whereas gastrin in extracts of cat antral mucosa was predominantly Component III. Gastric acid secretion in response to vagal stimulation was greater than can be accounted for by the action of gastrin alone and cannot be explained by differences in the known gastrin variants in the circulation during the two forms of stimulation. * Luccock Scholar.t Major award, Lancashire Education Committee.

SUMMARY The serum gastrin responses and the integrated gastrin responses to eating three meals of very different composition were studied in the same normal subjects on different days. Two meals, a milk meal of 500 ml, and a breakfast of eggs, toast, butter, marmalade, fruit juice and coffee, were eaten at breakfast time. The serum gastrin responses to these meals were compared and contrasted with the concentrations observed when the subjects fasted over the same time of day. A steak meal was eaten at lunch time. There were no significant differences between the mean serum gastrin concentrations to the three meals but each meal produced a significant increase in serum gastrin above fasting levels. When the prefeeding gastrin concentration was subtracted from the gastrin responses then the integrated responses to the steak meal were greater than those to either of the breakfast meals.Considerable variability in response to any one meal was observed within the group of subjects, but those subjects who produced high serum gastrin concentrations to one meal did so to the others. Conversely, a low response to one meal was reflected in low responses to the other two meals. Fasting serum gastrin concentration was correlated with the age of the subject. Repeatability of the response to one meal was tested in two subjects who ate the same meal on four separate occasions showing their responses to be repeatable.In the past decade the radioimmunoassay of gastrin has provided a new and sensitive tool which enables gastroenterologists to measure plasma gastrin concentrations in all manner of conditions, including the Zollinger-Ellison syndrome (Isenberg, Walsh, Passaro, Moore, and Grossman, 1972 (Ganguli and Hunter, 1972).In the quest to understand better the physiology of gastric secretion and to investigate the possible role of gastrin in the aetiology of peptic ulceration, different workers have used a variety of meals to stimulate and study gastrin secretion. The composition of the meals have ranged from two Oxo cubes (Byrnes, Young, Chisholm, and Lazarus, 1970), through a standard breakfast of boiled eggs, fruit juice, toast, marmalade and coffee to the more substantial steak meal and a sweet (Wyllie, Boulos,

SUMMARY1. Blood circulating in the cat is known to contain relatively large concentrations of gastrin components corresponding to Rehfeld's Components III and IV, whereas human blood has mostly Components II and III.2. Synthetic cat gastrin 17NS was continuously injected into chloralose anaesthetized cats and at 1, 10 and 40 min after the start of injection there were significantly greater concentrations of immunoreactive gastrin Component IV than Component III in arterial blood (P < 0-025 in each case). These concentrations were also greater than the total arterial gastrin concentration in the basal state.3. Cat blood with EDTA incubated at 37 'C with synthetic cat and natural porcine gastrins 17NS produced Component IV. Human blood with EDTA incubated in a similar way with natural and synthetic human gastrins 17NS did not produce any detectable Component IV. Cat blood incubated with natural porcine and synthetic cat gastrin 17NS at 0 'C did not produce any Component IV.4. We conclude that there may be an enzyme or enzymes in cat blood which cause the conversion of gastrin 17NS to Component IV.

SUMMARY1. Gastric acid secretion, and total gastric and mucosal blood flows (amidopyrine technique) were measured in anaesthetized cats. Oxygen contents of arterial and gastric venous blood were measured using an oximeter.2. Splanchnic nerve stimulation (10 Hz) significantly reduced the acid output and total gastric and mucosal blood flows produced in response to maximal gastrin pentapeptide infusions.3. The arterial haemoglobin concentration was significantly reduced during splanchnic nerve stimulation, and this is consistent with the hypothesis that the splanchnic nerve effect is directed against precapillary sphincters.4. During the period of inhibition, gastric oxygen consumption and acid secretion were reduced to similar degrees. There was no significant change in oxygen extraction by the stomach. 5. It remains possible that the splanchnic nerves directly inhibit the parietal cell activity.