Clinical application of pancreatic exocrine function tests / 临床肝胆病杂志

There are currently various pancreatic exocrine function tests with different indicators for detection, and there is still a lack of unified standard. This article summarizes the pancreatic exocrine function tests which are widely used or hold promise for application in clinical practice, briefly introduces the procedures of each test, and reviews their clinical practicability and advances, so as to provide a reference for the clinical application and research ideas of pancreatic exocrine function tests.

Clinical application of pancreatic exocrine function examination / 第二军医大学学报

Pancreatic exocrine function examination is mainly divided into direct examination and indirect examinationmethods. Direct examination methods include secretin test, secretin-caerulein test, endoscopic pancreatic function test, secretin-stimulated magnetic resonance pancreatography, Lundh test, etc. Indirect examination methods are comprised of routine serological testing, fecal fat detection, fecal enzyme detection, breath test, urine analysis of specific substances and so on. Direct examination has higher accuracy than indirect examination, but it is more invasive and cumbersome than noninvasive indirect examination. In this review, we summarized the clinical application and progress of pancreatic exocrine function examination.

Assessment of mild chronic pancreatitis：the utility of diffusion weighted imaging before and after secretin stimulation / 中华放射学杂志

Objective To explore the diagnostic value of DWI after secretin stimulation for the diagnosis of mild chronic pancreatitis (CP). Methods This was a prospective study. Ninety-nine consecutive individuals including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 36 severe CP patients underwent secretin DWI and faecal elastase 1(FE-1) testing. The subjects were grouped by Cambridge classification about endoscopic retrograde cholangiography (ERCP), CT and ultrasonography. Secretin stimulated diffusion weighted imaging(S-DWI), the ADCs, time to peak ADCs and FE-1 were performed on all subjects. The changes of pancreatic ADC values were observed before and after the injection of secretin. All ADCs and FE-1 were compared between groups with single factor analysis of variance, and the correlation between ADCs and FE-1 was determined with Pearson analysis. ROC curves were performed to identify the diagnostic efficacy of DWI related measures. Results Eight patients with severe CP were excluded because the significant atrophy of the pancreatic parenchyma prohibited the evaluation of ADC measurement. Ninety-one individuals were divided into five groups including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 28 severe CP patients. The mean baseline and peak ADCs were higher in the healthy volunteers than in other groups, with significant differences (P<0.05). There was no ADC peak in severe CP patients. There were significant differences between the mean baseline ADCs and the peak ADCs in the other groups (P<0.05). The mild and moderate CP groups showed a delayed peak. The area under curve (AUC) of the mean baseline and peak ADCs, time to peak ADCs for differentiating mild CP was 0.818, 0.912 and 0.965, respectively. Using 4.67 min as the cutoff value, time to peak ADCs were most accurate for differentiating healthy from risk patients and those with evident pancreatitis, yielding a sensitivity of 80.0%and a specificity of 100.0%. Good correlations between baseline and peak ADCs, time to peak ADCs, and FE-1 were shown(r=0.57, 0.72 and-0.84, P<0.01). Conclusions Using the peak and time to peak ADCs may improve the detection of risk and mild CP. Secretin-enhanced DWI is a noninvasive, convenient and accurate method.

Ultrasonido endoscópico en patologías del páncreas / Endoscopic ultrasound in pancreatic diseases

El ultrasonido endoscópico (EUS) ha revolucionado el diagnóstico y el manejo de muchas patologías de la vía digestiva, particularmente la patología pancreática, convirtiéndose en un examen prácticamente imprescindible en el abordaje diagnóstico y terapéutico de un paciente con un problema de páncreas. Es necesario dejar en claro que el método no es único y que para lograr una sensibilidad alta y cumplir el objetivo de realizar lo más adecuado, debe sumarse a otros métodos de acuerdo a cada caso, como la ecografía, la tomografía axial computarizada (TAC), la resonancia magnética (MRI) en sus diferentes modalidades, y las pruebas del laboratorio clínico microbiológico y patología. En este artículo se revisarán algunos casos de enfermedades evaluadas con este método, que muestran por qué el EUS, es una herramienta clave para el médico de urgencias y de consulta externa, el internista, el cirujano, el médico del servicio hospitalario y el personal de salud en general, al momento de definir, clasificar y orientar el manejo de determinadas patologías en el tubo digestivo. El EUS es una importante ayuda y no debe ser extraña al personal médico, debe tenerla presente junto a las demás pruebas diagnósticas en patología pancreática. Se señalarán los aspectos más relevantes en cada caso y las indicaciones del EUS.

Endoscopic ultrasound (EUS) has revolutionized the diagnosis and management of many diseases of the digestive tract, particularly the pancreatic ones, becoming a practically essential test in the diagnosis and therapeutic management of a patient with a pancreatic problem. It's necessary to establish the final diagnosis are necesary many tests to achive high sensitivity. It should join with other methods according to each case, such as ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) in its various forms, and chemical, microbiological and pathology tests. In this article we reviewed some cases of pathologies evaluated by this diagnosis test, which demonstrate why the EUS, is a key for the emergency and outpatient physician, internist, surgeon, doctor of the hospital service and staff health in general, when defining, classifying and guide the management of certain diseases in the digestive tract. The EUS is an important tool and should not be foreign to the medical staff, who must consider it, with other diagnostic tests for pancreatic disease. This article point out the most important aspects in each case and indications of EUS.

The Effect of Secretin on Pepsin Secretion in Heidenhain Pouch

PURPOSE: This research was done to confirm the effect of secretin on pepsin secretion and to study whether or not feeding can depress the secretin-stimulated pepsin secretion (SSPS) with its related factors. METHODS: Heidenhain (HP) and Pavlov pouches (PP) were made in 6 dogs and cannulae were then inserted into the pouches. The fluids were collected through the cannula every 10 minutes for 3 hours in various conditions, including resting, feeding, secretin perfusion, acidification of the stom-ach and, gastric distension. A modified Anson's hemoglobin method was used to check the amount of pepsin. RESULTS: When secretin was perfused in the HP, there was no increase of pepsin secretion at 0.1 and 0.2 CU/kg/hr, but the pepsin secretion increased at 0.4 and 1.0 CU/kg/hr. Compared to the control, ANOVA showed significant differences for secretin 0.4 CU/kg/hr (P<0.01) and for secretin 1.0 CU/kg/hr (P<0.001). When milk was administered through the gastric cannula after secretin stimulation, pepsin production increased in the PP, but pepsin secretion in the HP dropped close to the basal level after administering milk. This depression was not related to acidity of the milk. ANOVA showed significant differences for secretin with milk vs milk alone (P<0.0005) and vs secretin alone (P<0.0025). The inhibition of SSPS was not observed with any gastric distension or acid perfusion. CONCLUSION: In the HP, secretin increased the pepsin secretion and the vagus nerve has an inhibitory effect on pepsin secretion under secretin stimulation. Milk feeding depressed the SSPS, and that depression was not related to pH of the food and gastric distension. Further study is needed in order to clarify the mechanism of depression.

Secretin induces neurite outgrowth of PC12 through cAMP-mitogen-activated protein kinase pathway

The gastrointestinal functions of secretin have been fairly well established. However, its function and mode of action within the nervous system remain largely unclear. To gain insight into this area, we have attempted to determine the effects of secretin on neuronal differentiation. Here, we report that secretin induces the generation of neurite outgrowth in pheochromocytoma PC12 cells. The expressions of Tau and beta-tubulin, neuronal differentiation markers, are increased upon secretin stimulation. In addition, secretin induces sustained mitogen-activated protein kinase (MAPK) activation and also stimulates the cAMP secretion. Moreover, the neurite outgrowth elicited by secretin is suppressed to a marked degree in the presence of either PD98059, a specific MAPK/ERK kinase (MEK) inhibitor, or H89, a specific protein kinase A (PKA) inhibitor. Taken together, these observations demonstrate that secretin induces neurite outgrowth of PC12 cells through cAMP-MAPK pathway, and provide a novel insight into the manner in which secretin participates in neuritogenesis.

The relationship between the bile flow and cholecystokinin (CCK), gastrin (GAS),and secretin (SEC) hormones in the rabbits after traumatic stress / 中华急诊医学杂志

Objective To study the relationship between the bile flow and CCK, GAS and SEC hormones in the rabbits after traumatic stress. Methods Bile flow was counted by bile duct intubation and the models of traumatic stress were produced by cutting the hind legs of rabbits. Bile flow, CCK, GAS and secretin in plasma were measured before and after stress. Results Bile flow after traumatic stress was significantly increased (P

El centenario de las hormonas: Un recuerdo de Ernest H. Starling y William M. Bayliss / On the centennial of hormones: A tribute to Ernest H. Starling and William M. Bayliss

En junio de 2005 se cumplió el primer centenario de la introducción de la palabra hormona para definir al mensajero químico que originado en un tejido viaja a través de la circulación para alcanzar otro tejido distante y ejercer un efecto específico. Ernest H. Starling presentó en junio de 1905 las Conferencias Croone en las que desarrolló la teoría del control químico del organismo como una culminación de sus previas investigaciones que había realizado en colaboración con el fisiólogo William M. Bayliss sobre la fisiología del corazón, el intercambio capilar, la reabsorción tubular del glomérulo renal y el peristaltismo intestinal. La primera hormona recibió el nombre de secretina y su descubrimiento desencadenó un incontable número de investigaciones multidisciplinarías que han permitido el avance en el conocimiento de la biología molecular y particularmente en el área de la endocrinología.

Ernest H. Starling introduced the term hormone 100 years ago in his Croonian Lectures to the Royal College of Physicians in June 1905. It was demonstrated for the first time that one part of the body could influence the function of another distant part. Starling for the first time suggested the word hormone. This review attempts to trace the development of studies in endocrinology, beginning in the middle of the nineteenth century. Starling discovered secretin, the first hormone, in collaboration with William M. Bayliss, and they introduced the hormone concept with recognition of chemical regulation. Thus the name hormone sparked multidisciplinary research in endocrinology and molecular biology, which shed light on the chemical communication within the organism.

The Clinical Usefulness of Fecal Elastase-1 Test as an Exocrine Pancreatic Function Test for the Diagnosis of Chronic Pancreatitis / 대한소화기내시경학회지

BACKGROUND/AIMS: The quantitative analysis of fecal elastase-1 has been proposed as a noninvasive test for the examination of pancreatic exocrine function. Therefore, we evaluated the diagnostic value of fecal elastase-1 by comparing with endoscopic intraductal secretin test (IDST) which is used as a direct exocrine function test for the diagnosis of chronic pancreatitis. METHODS: Fecal elastase-1 concentrations were measured by ELISA in spot stool samples of 40 healthy control subjects, 21 patients with liver disease, and 12 patients with chronic pancreatitis diagnosed with endoscopic retrograde cholangiopancreatography (ERCP) and IDST. Chronic pancreatitis were then sub-classified into mild (I), moderate (II) and severe form (III), using the Cambridge classification according to ERCP finding. The linear regression analysis to evaluate the correlation between the concentration of fecal elastase-1 and IDST was performed during ERCP. The cut-off value of fecal elastase-1 to discriminate chronic pancreatitis was calculated based on receiver operating characteristic curve, and the clinical usefulness of fecal elastase-1 in the diagnosis of chronic pancreatitis was evaluated. RESULTS: There were several significant correlations between fecal elastase-1 and various parameters of IDST: pancreatic juice secretory volume (r=0.797, p<0.002), bicarbonate concentration (r=0.846, p<0.001), elastase-1 concentration in pancreatic juice (r=0.671, p<0.017), and amylase output (r=0.783, p<0.003). The mean value of fecal elastase-1 concentration in the patients with chronic pancreatitis (197+/-77microgram/g stool) was significantly lower than those in the healthy control subjects (815+/-133microgram/g stool) and patients with liver disease (594+/-206microgram/g stool) (p<0.05). The cutoff value of fecal elastase-1 to discriminate between the healthy control and chronic pancreatitis patients was 201microgram/g stool. With this cutoff value, the accuracy, sensitivity, and specificity of fecal elastase-1 to diagnose chronic pancreatitis were 78.8%, 67.7%, and 82.5%, respectively, compared to the morphological severity (the sensitivity of mild, moderate, and severe chronic pancreatitis was 33.3%, 66.7%, 83.3%, respectively). CONCLUSIONS: Measurement of fecal elastase-1 is a reliable and sensitive non-invasive test for the diagnosis of moderate to severe forms of chronic pancreatitis.

Roles of Gonadal Steroids on Exocrine Secretion of Isolated Perfused Rat Pancreas

To clarify the roles of gonadal steroids on pancreatic exocrine secretion, effects of progesterone and estradiol-17beta on spontaneous and secretagogue-induced exocrine response of isolated perfused rat pancreas were investigated. Intra-arterial infusion of progesterone resulted in significant increase of the spontaneous pancreatic fluid and amylase secretion dose-dependently. However, estradiol-17beta did not exert any influence on spontaneous pancreatic exocrine secretion. Exogenous secretin, cholecystokinin (CCK), and acetylcholine markedly stimulated pancreatic fluid and amylase secretion. Progesterone initially enhanced secretin-induced amylase secretion, but this stimulatory response declined thereafter to basal value. Moreover, secretin-induced fluid secretion was not affected by infusion of progesterone. Therefore, initial increase of secretion-induced amylase secretion by progesterone seems to be a non-specific action by washout effect of secretin. Estradiol-17beta failed to change the secretin-induced fluid and amylase secretion. Both progesterone and estradiol-17beta did not exert any influence on CCK-induced fluid and amylase secretion. Acetylcholine-induced exocrine secretion of isolated perfused pancreas also was not affected by intra-arterial infusion of progesterone or estradiol-17beta. It is concluded from the above results that progesterone could enhance the spontaneous pancreatic fluid and amylase secretion of isolated perfused rat pancreas through non-genomic short- term action, and that these effects could be masked by more potent stimulants such as secretin, CCK, and acetylcholine.

Effect of serotonin on subdiaphragmatic vagus nerve afferent discharge and its mechanism in rats / 第三军医大学学报

Objective To investigate the effect and mechanism of serotonin (5-HT) and secretin(SEC) on afferent discharge of vagus in rats. Methods Spontaneous afferent discharge of subdiaphragmatic vagus nerve was recorded in urethane anesthetized rats. The effects of 5-HT, 5-HT3 receptor antagonist and 5-HT+SEC on the discharge of subdiaphragmatic vagus nerve were investigated by intravenous injection of different dosage of 5-HT(3, 10, 30 ?g/kg), Granisetron (1 mg/kg) and 5-HT+SEC. Results Intravenous 5-HT caused obvious exciting effect on spontaneous afferent discharge of subdiaphragmatic vagus nerve. The 5-HT3 receptor antagonist significantly inhibited the effects of 5-HT. 5-HT+SEC could augment the effect of 5-HT on spontaneous discharge. Conclusion The exciting effect of 5-HT on afferent discharge of subdiaphragmatic vagus nerve is possibly mediated by 5-HT3 receptor related to vagus nerve afference. Secretin can augment the exciting effect of 5-HT on spontaneous discharge of vagus afferent nerve.

Altered Secretory Pattern of Pancreatic Enzymes and Gastrointestinal Hormones in Streptozotocin-induced Diabetic Rats

This study was performed to investigate the pancreatic exocrine dysfunction in streptozotocin- induced diabetic rats. Changes in pancreatic enzymes secretion and in pancreatic enzymes content were observed. The output and the tissue content of amylase were significantly reduced in diabetic rats, while the output and the content of lipase were increased. Plasma secretin and cholecystokinin (CCK) concentrations of diabetic rats were significantly increased compared to those of normal rats. The altered pancreatic exocrine function was abolished by the exogenous insulin administration. The exogenous insulin also restored the increased plasma secretin and CCK concentrations. From the above results, it is suggested that, in streptozotocin-induced diabetic rats, anticoordinated changes in pancreatic enzymes secretion as well as pancreatic enzymes content are attributable to insulin deficiency and that the insulin deficiency is responsible for the increased plasma concentrations of both secretin and CCK. However, it is not clear whether the elevated plasma secretin and CCK concentrations played a direct role in changes of pancreatic exocrine function.

Effects of gamma-Aminobutyric Acid on Pancreatic Amylase Secretion Evoked by Sodium Oleate in Anesthetized Rats

gamma-Aminobutyric Acid (GABA) is contained in pancreatic islet beta-cells although its physiological role in pancreatic exocrine function is completely unknown at the present time. Recently, we have reported that exogenous GABA enhances secretagogue-evoked exocrine secretion in the isolated, perfused rat pancreas. This study was aimed to investigate an effect of exogenous GABA on pancreatic exocrine secretion in vivo evoked by intestinal stimulation. Rats were anesthetized with urethane (1.4 g/kg) after 24-h fast with free access to water. GABA (10, 30 and 100micromol/kg/h), given intravenously, did not change spontaneous pancreatic amylase secretion but dose-dependently elevated the amylase secretion evoked by intraduodenal sodium oleate (0.05 mmol/h). GABA (30micromol/kg/h) also further increased the amylase secretion stimulated by CCK+(30 pmol/kg/h) plus secretin (20 pmol/kg/h) but failed to modify the amylase secretion induced by secretin alone. GABA (10, 30 and 100micromol/kg/h) also dose-dependently elevated pancreatic amylase secretion evoked by CCK+alone. Bicuculline (100micromol/kg/h), a GABAA-receptor antagonist, markedly reduced the GABA-enhanced pancreatic responses to sodium oleate, CCK+plus secretin or CCK+alone. The results indicate that GABA enhances the sodium oleate-evoked pancreatic amylase secretion via GABAA-receptors in anesthetized rats, which may account for elevating the action of CCK+released by sodium oleate.

The diagnostic value of serum and fecal pancreatic elastase-1 in patients with pancreatic disease / 대한내과학회지

BACKGROUND: The aims of this study were to evaluate the diagnostic value of pancreatic elastase-1(PE-1) in patients with pancreatic diseases and compare the significance of PE-1 with that of pancreatic exocrine function test by pure pancreatic juice (PPJ) collection. METHODS: For evaluation of PE-1, seventy nine patients with pancreatic diseases were examined. For evaluation of exocrine pancreatic function by PPJ, twenty three patients with Chronic pancreatitis(CP) were examined. PPJ was collected by endoscopic cannulation of main pancreatic duct under the intravenous bolus injection of secretin (0.25 CU/kg body weight) and cholecystokinin (CCK, 40 ng/kg body weight). RESULTS: Pancreatic exocrine functions were significantly decreased in patients with CP showing moderate and severe ductal changes on pancreatogram. The mean concentration of fecal PE-1 was significantly decreased in patients with CP and pancreatic cancer, but not in patients with acute pancreatitis. When we analyzed the PE-1 concentration according to Cambridge classification, the concentration of fecal PE-1 was significantly decreased only in patients with moderate and severe CP. With a cut off of 200 ug fecal PE-1/g, the sensitivity of PE-1 was 25%, 60%, and 100%, respectively, for mild, moderate and severe CP, and the specificity was 88.1%. The mean concentration of serum PE-1 was increased both in patients with acute and chronic pancreatitis, but there was no difference between both group. CONCLUSION: Fecal PE-1 is useful for diagnosis of pancreatic exocrine insufficiency in patients with CP, especially in moderate and severe grade of pancreatic exocrine insufficiency. The diagnostic value of fecal PE-1 was also similar to secretin-CCK test in pancreatic exocrine insufficiency.

Effects of GABA on pancreatic exocrine secretion of rats

Since GABA and its related enzymes had been determined in beta-cells of pancreas islets, effects of GABA on pancreatic exocrine secretion were investigated in the isolated perfused rat pancreas. GABA, given intra-arterially at concentrations of 3, 10, 30 and 100 microM, did not exert any influence on spontaneous or secretin (12 pM)-induced pancreatic exocrine secretion. However, GABA further elevated cholecystokinin (10 pM)-, gastrin-releasing peptide (100 pM)- or electrical field stimulation-induced pancreatic secretions of fluid and amylase, dose-dependently. The GABA-enhanced CCK-induced pancreatic secretions were completely blocked by bicuculline (10 microM), a GABAA receptor antagonist but not affected by saclofen (10 microM), a GABA(B) receptor antagonist. The enhancing effects of GABA (30 microM) on CCK-induced pancreatic secretions were not changed by tetrodotoxin (1 microM) but partially reduced by cyclo-(7-aminoheptanonyl-Phe-D-Trp-Lys-Thr[BZL]) (10 microM), a somatostatin antagonist. In conclusion, GABA enhances pancreatic exocrine secretion induced by secretagogues, which stimulate enzyme secretion predominantly, via GABA(A) receptors in the rat pancreas. The enhancing effect of GABA is partially mediated by inhibition of islet somatostatin release. GABA does not modify the activity of intrapancreatic neurons.

Serotonin and pancreatic duct function

1. 5-HT inhibits spontaneous fluid secretion as well as stimulated secretion with secretin (cAMP mediated) or ACh (Ca2+ mediated) in the isolated guinea pig pancreatic ducts. 2. The inhibitory effect of 5-HT is reversible and is dependent on the concentration in the range 0.01-0.1 microM, which is much lower than those that affect intestinal motility and secretion. 3. The 5-HT3 receptor in duct cells appears to mediate the inhibitory effect of 5-HT. 4. [Ca2+]i is unlikely to mediate the inhibitory effect of 5-HT.

Usefulness of Intraductal Secretin Test in Assessing Exocrine Pancreatic Function in Patients with Chronic Pancreatitis / 대한소화기내시경학회지

BACKGROUND/AIMS: The duodenal intubation test (duodenal secretin test; DST) is now considered the 'gold standard' test of exocrine pancreatic function in detecting exocrine pancreatic dysfunction in patients with chronic pancreatitis. However, the DST has not been widely used, because it is time-consuming, invasive, and labor-intensive. On the other hand, intraductal secretin test (IDST) with endoscopic retrograde cannulation of the main pancreatic duct has been showed similar diagnostic efficiency compared with DST. We assessed the clinical usefulness of IDST and investigated parameters for assessing impaired pancreatic function of IDST. METHODS: Pure pancreatic juices were collected from 12 patients with chronic pancreatitis by endoscopic cannulation after a bolus intravenous injection of secretin 100 U, for 15min in three 5-min intervals. Five parameters of IDST were measured, and the sensitivity, specificity, and accuracy of IDST evaluated compared with ERP. RESULTS: When we regarded mean-1.5 SD as the lower limits of IDST, the diagnostic sensitivity, specificity, and accuracy of five parameters to detect chronic pancreatitis were 91.7-100%, 75-87.5%, and 85-90%, respectively. Among five parameters, pancreatic juice secretory volume, bicarbonate concentration, and amylase output showed the highest diagnostic accuracy, followed by lipase output and bicarbonate output. A 10-min collection showed as much information as a 15-min collection. CONCLUSIONS: 10-min intraductal secretin test is useful as the conventional exocrine pancreatic function test in detecting exocrine pancreatic dysfunction in patients with chronic pancreatitis and the most discriminatory parameters are pancreatic juice secretory volume, bicarbonate concentration, and amylase output.

A Trial Study of Kikyo-to on Abdominal Symptoms in Chronic Pancreatitis Patient / 日本東洋医学雑誌

The authors investigated the activity of Kikyo-to on the intestinal hormones, cholecystokinin (CCK) and secretin, released in healthy humans. The clinical efficacy of Kikyo-to on the abdominal symptoms associated with chronic pancreatitis was also investigated. In healthy volunteers, Kikyo-to (5g) significantly increased plasma CCK and secretin concentrations 30 minutes after treatment. In chronic pancreatitis patients, abdominal pain, abdominal tenderness, nausea and diarrhea were decreased by treatment with Kikyo-to (7.5g/day; divided into three doses). In conclusion, Kikyo-to improved the complaints of chronic pancreatitis, especially abdominal pain. The presumed mechanism was that Kikyo-to stimulated pancreatic exocrine secretion by the release of intestinal hormones, CCK and secretin.

Secretin inhibits vagal afferent nerve discharge in response to gastric distension in rats / 重庆医科大学学报

Objective:To study the effect of secretin on subdiaphragmatic vagal afferent response by gastric distension. Methods: Experiments were performed on anesthetized rats. The sensory impulses of subdiaphragmatic vagal nerve were recorded using a window discriminator. Through a midline abdominal incision, a polyethylene cannula (1.0mm ID) for duodenal infusion was inserted into the proximal duodenum 0.5mm distal to the pylorus.Another cannula was placed into jejunum 20 cm distal to the ligament of Treitz.Gastric distension was produced by injecting saline at 37℃ into a small balloon via a polyvinyl tube.Results:Intravenous injection of secretin in a dose of 5.0 pmol/kg/h inhibited significantly the response of afferent discharges induced by gastric distension( n=7, P 0.05). It showed that exogenous secretin in a dose of 5.0pmol/kg/h, in the physiological dose range, played an inhibitory effect. 0.03N HCl was infused intraduodenally at 9 ml/h for 20 min in anesthetized rats with gastric cannulas, ligation of the pylorus, respectively.0.1 ml of a rabbit antisecretin serum (titer=l:l,000,000) was injected intravenously in a bolus 20～40min before HC1 was administered. During the duodenal infusion of 0.03N HCI the gastric distension-vagal afferent responses were suppressed significantly.( n=8, P