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A BSTRACT The interaction of gastrin and secretin, in the regulation of human lower esophageal sphincter competence, was studied in 54 normal subjects. A doseresponse curve, for the lower esophageal sphincter, was constructed from the rapid intravenous injections of synthetic gastrin I (amino acid sequence 2-17). This curve was sigmoid shaped and showed a peak response that was 460.0 ±24.0% (mean ±2 SE) of the initial sphincter pressure, at a dose of 0.7 /g/kg of gastrin I. Secretin, either endogenously released by duodenal acidification, or exogenously administered as a single intravenous injection, markedly reduced the peak response of the sphincter to gastrin I. To ascertain the character of this inhibition, a gastrin I dose-response curve was obtained during a continuous intravenous secretin infusion. This curve showed a parallel shift to the right, with the maximal sphincter response to gastrin I still attainable at higher doses. A sphincter, endogenously stimulated by gastrin, showed a dose-related reduction in pressure with rapid intravenous injections of secretin. At the level of resting sphincter pressure, response to secretin diminished, and larger doses were required for comparable reduction in pressure. These studies indicate: (a) Secretin interacts with gastrin in the physiological regulation of human lower esophageal sphincter competence; (b) Secretin is a sensitive inhibitor to gastrin stimulation of the lower esophageal sphincter; (c) This inhibitory effect of secretin is competitive in character.

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A B STRA CT Intraluminal manometric studies were carried out in 19 patients with untreated achalasia and in 20 normals. Lower esophageal sphincter (LES) pressure was 50.5 ±4.6 mm Hg in patients with achalasia as compared with 19.4 ±1.3 mm Hg in the normal group.In both groups, the LES pressure was lowered when exogenous 0.1 N HCl was placed into the stomach. Although the nadir of pressure attained with acid suppression was the same, the per cent inhibition was significantly greater in patients with achalasia. Serum gastrin levels were the same in the two groups studied. The patients with achalasia, pre-and postpneumatic dilatation, showed a supersensitivity to exogenous intravenous gastrin I, as compared with normals. These data suggest that high, acid-suppressible levels of LES pressure, in patients with achalasia, are due to supersensitivity to endogenous gastrin. INTRODUCTIONIn patients with achalasia, dysfunction of the lower esophageal sphincter (LES)' plays a major role in the pathogenesis of impaired esophageal emptying. Although this point is well recognized, a clear understanding of the pathophysiology of this dysfunction is not available. The classic concept of a normotensive LES, which fails to relax upon deglutition (1, 2) has been questioned (3). It has been suggested that LES dysfunction consisted of a marked elevation in LES pressure and a limited, but distinct, ability to relax upon deglutition. By this latter concept, LES hypertension would play a major role in the impairment of esophageal emptying. It is the purpose of this study to utilize a method of proven

A B S T R A C T The purpose of this study was to evaluate the role of gastrin in the genesis of lower esophageal sphincter (LES) pressure by the use of a high titer gastrin antiserum. Intravenous infusions of increasing amounts of rabbit gastrin antiserum, but not control antiserum, produced graded reductions in the resting LES pressure in anesthetized opossums. A maximal inhibition in LES pressure of 80.0 ±3.1% (mean +SE) was achieved when gastrin antiserum was administered in an amount estimated to bind almost all endogenous circulating gastrin in the opossum. Gastrin antiserum also inhibited the LES response to endogenous gastrin release (gastric deacidification) and to exogenous intravenous administration of gastrin I. The inhibition of the LES response to exogenous gastrin I by gastrin antiserum could be eliminated by giving excess gastrin I. Studies performed in vitro showed that gastrin antiserum inhibited the contractile response of LES circular muscle to gastrin I, but not to acetylcholine. These studies indicate that gastrin antiserum: (a) specifically antagonized the response of LES circular muscle to gastrin, in vitro; (b) diminished the LES response to the endogenous release and to the exogenous administration of gastrin; and (c) markedly reduced the resting level of LES pressure. We conclude that endogenous gastrin is the major determinant of resting LES pressure. INTRODUCTION The intrinsic strength of the physiological lower esophageal sphincter (LES)1 is the major determinant of A portion of this work was presented before the Mid-