Application of small intestine double stoma and succus entericus reinfusion in the patients with severe intra-abdominal infection / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To evaluate the application of small intestine double stoma and succus entericus reinfusion in the patients with severe intra-abdominal infection.</p><p><b>METHODS</b>Ten patients with high intestinal perforation from February 2005 to November 2014 were enrolled in the study. All the cases received emergency operation. Small bowel with intestinal perforation was resected, and double stoma was applied in the proximal and distal small intestine. When abdominal infection under control, total enteral nutrition was successfully administered from nasogastric tube. The succus entericus from the proximal intestine was collected and transfused back to the distal intestine. Stool was collected and fecal nitrogen, fat and carbohydrate contents were determined. Related serum protein levels were measured.</p><p><b>RESULTS</b>As compared to pre-reinfusion, the absorption rate of carbohydrate [(90.9±7.8)% vs. (82.7±15.2)%], fat [(87.6±6.4)% vs. (59.1±10.8)%], and nitrogen [(82.4±9.8)% vs. (67.2±15.4)%] increased after succus entericus reinfusion (P<0.05). The serum protein levels increased significantly as well[fibronectin: (285.6±3.6) vs. (157.0±22.6) mg/L, P<0.01; transferrin: (4.86±0.21) vs. (3.60±0.25) g/L, P<0.05; pre-albumin: (291.3±112.5) vs. (199.1±53.3) mg/L, P<0.05].</p><p><b>CONCLUSION</b>Small intestine double stoma and succus entericus reinfusion are effective in improving the absorption of carbohydrate, fat and nitrogen in the patients with severe intra-abdominal infection.</p>

Lubiprostone Increases Small Intestinal Smooth Muscle Contractions Through a Prostaglandin E Receptor 1 (EP1)-mediated Pathway

BACKGROUND/AIMS: Lubiprostone, a chloride channel type 2 (ClC-2) activator, was thought to treat constipation by enhancing intestinal secretion. It has been associated with increased intestinal transit and delayed gastric emptying. Structurally similar to prostones with up to 54% prostaglandin E2 activity on prostaglandin E receptor 1 (EP1), lubiprostone may also exert EP1-mediated procontractile effect on intestinal smooth muscles. We investigated lubiprostone's effects on intestinal smooth muscle contractions and pyloric sphincter tone. METHODS: Isolated murine small intestinal (longitudinal and circular) and pyloric tissues were mounted in organ baths with modified Krebs solution for isometric recording. Basal muscle tension and response to electrical field stimulation (EFS; 2 ms pulses/10 V/6 Hz/30 sec train) were measured with lubiprostone (10(-10)-10(-5) M) +/- EP1 antagonist. Significance was established using Student t test and P < 0.05. RESULTS: Lubiprostone had no effect on the basal tension or EFS-induced contractions of longitudinal muscles. With circular muscles, lubiprostone caused a dose-dependent increase in EFS-induced contractions (2.11 +/- 0.88 to 4.43 +/- 1.38 N/g, P = 0.020) that was inhibited by pretreatment with EP1 antagonist (1.69 +/- 0.70 vs. 4.43 +/- 1.38 N/g, P = 0.030). Lubiprostone had no effect on circular muscle basal tension, but it induced a dose-dependent increase in pyloric basal tone (1.07 +/- 0.01 to 1.97 +/- 0.86 fold increase, P < 0.05) that was inhibited by EP1 antagonist. CONCLUSIONS: In mice, lubiprostone caused a dose-dependent and EP1-mediated increase in contractility of circular but not longitudinal small intestinal smooth muscles, and in basal tone of the pylorus. These findings suggest another mechanism for lubiprostone's observed clinical effects on gastrointestinal motility.

Study on stability of major pharmaceutical ingredients of vladimiriae radix before and after being roasted in artificial gastric juice, artificial intestinal juice and isolated rat gastric, intestinal or colonic incubation juice / 中国中药杂志

<p><b>OBJECTIVE</b>To study the stability of costunolide (COS) and dehydrocostus lactone (DEH) of Vladimiriae Radix before and after being roasted in artificial gastric juice, artificial intestinal juice and isolated rat gastric, intestinal or colonic incubation juice.</p><p><b>METHOD</b>The HPLC method was used for the determination of the mass concentration of COS and DEH Vladimiriae Radix before and after being roasted artificial gastric juice, artificial intestinal juice and isolated rat gastric, intestinal or colonic incubation juice. The samples were incubated with isolated rat stomach, small intestine; colon was used to study physical adsorption, absorption or degradation parameters.</p><p><b>RESULT</b>COS of Vladimiriae Radix before or after being roasted was unstable in artificial gastric juice, with the average degradation constants as 0.758 0 and 0.531 1. Having been roasted, it showed an increasing stability with a significant difference (P < 0.01). Both of COS and DEH of Vladimiriae Radix before or after being roasted showed high adsorption, uptake or degradation (2 h), and it had significant difference between different parts.</p><p><b>CONCLUSION</b>COS was unstable in artificial gastric juice (unprocessed Vladimiriae Radix has a higher degradation rate). Isolated rat stomach, small intestine, colon can adsorb, take, degrade COS and DEH of Vladimiriae Radix before or after roasting process obviously and differently. It provides basis for studies on the absorption mechanisms of effective ingredients of Vladimiriae Radix before and after being roasted.</p>

Study on in vitro release empirical method and the release mechanism of budesonide colonic localization tablet / 药学学报

The three-step dissolution experiment was established to investigate the in vitro release of budesonide colon-specific tablet and to elucidate the drug release mechanism by fitting to different mathematical models. The physiological parameters of stomach, small intestine and colon such as pH value, intestinal flora, specific organic enzyme, vermiculation and conveying time were mimicked to plot the in vitro dissolution, separately. Sample were taken at predetermined time intervals in 24 h and the accumulated drug releases were determined by using HPLC method. Drug release curves of the localization tablets were fitted to various mathematical models. It shows that no drug release was found in 2 h. About 5% release was determined after 6 h while 77.5% accumulated release was reached within 24 h. Drug release from the in house formulation fitted well into first-order model. The three-step dissolution method could be used to evaluate the colon-specific characteristics of budesonide colonic localization tablet. The drug release behavior of the localization tablet conforms to the drug release mechanisms of controlled porosity osmotic pump where osmotic pressure is the main driving force for controlled delivery of drugs.

Effects of rhubarb on the immune substances secreted from intestine in mice / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the therapeutic mechanism of rhubarb in protecting the intestinal muco-membranous barrier in the mice.</p><p><b>METHOD</b>Bal b/c mice were divided into 2 groups, gavaged with normal saline and 10% rhubarb decoction, respectively. The animals were killed after 24 hours after the treatments. The intestinal juice was collected after intestinal lavage and centrifuged for determination of IgA, total protein, C3, high density lipoprotein, type II PLA2 activity, and content of lysozyme. At the same time, 40 mg of small intestine were incised in each mouse. Reverse transcription polymerase chain reaction (RT-PCR) and gel image analysis were performed to detect the content of the cryptdin gene expression.</p><p><b>RESULT</b>The content of IgA, total protein, the C3, lysozyme, and the type II PLA2 activity in intestinal lavaged juice exhibited the statistical differences between the two groups (P < 0.05). There were no significant difference in the ontents of HDL, cryptdin-1 and cryptdin-4 gene expression between the two groups (P > 0.05).</p><p><b>CONCLUSION</b>Rhubarb could increase secretion of several immune associated substances of the mucous membrane in normal intestine, indicating a possibility to abate the injury of intestine mucus resulted from severe stress induced by trauma, burn and shock. Through above mechanisms Rhubarb may also reduce the incidence of bacterial translocation and systemic inflammatory reaction syndrome (SIRS).</p>

Digestive stimulant action of spices: a myth or reality?

Spices have long been recognized for their digestive stimulant action. Several spices are also employed in medicinal preparations against digestive disorders in traditional and Indian systems of medicine. Earlier reports on the digestive stimulant action of spices are largely empirical; only in recent years, this beneficial attribute of spices has been authenticated in exhaustive animal studies. Animal studies have shown that many spices induce higher secretion of bile acids which play a vital role in fat digestion and absorption. When consumed through the diet also spices produce significant stimulation of the activities of pancreatic lipase, amylase and proteases. A few of them also have been shown to have beneficial effect on the terminal digestive enzymes of small intestinal mucosa. Concomitant with such a stimulation of either bile secretion or activity of digestive enzymes by these spices, leading to an accelerated digestion, a reduction in the food transit time in the gastrointestinal tract has also been shown. Thus, the digestive stimulant action of spices seems to be mediated through two possible modes: (i) by stimulating the liver to secrete bile rich in bile acids, components that are vital for fat digestion and absorption, and (ii) by a stimulation of enzyme activities that are responsible for digestion. This review highlights the available information on the influence of spices on the digestive secretions and enzymes.

Helicobacter pylori Vacuolating Toxin Exhibits Polar Activity of Cl Secretion and Secretory Response to Carbachol in T84 Cells

To investigate whether VacA (vacuolating toxin) produced by Helicobacter pylori Korean stain 99 induces intestinal secretion, purified VacA was added to T84 cell monolayers mounted in Ussing chambers, and electrical parameters were monitored. Mucosal addition of low pH-pretreated VacA increased short circuit current (Isc). The effect was time- and dose-dependent and saturable. The time-to-peak Isc was concentration-dependent. Chloride channel inhibitors, niflumic acid or 5- nitro-2- (3-phenylpropylamino) -benzoate (NPPB), inhibited VacA-stimulated Isc. Carbachol (CCh) -induced increase of Isc was prolonged by the addition of VacA to the mucosal side only. The effect was unaltered by the addition of niflumic acid. VacA did not show cytopathic effects. These studies indicate that VacA is a nonlethal toxin that acts in a polar manner on T84 monolayers to potentiate Cl secretion and the response to CCh secretion without decrease in monolayer resistance. VacA may contribute to diarrhea diseases in human intestinal epithelial cells.

Epidemiología de la candidiasis diseminada neonatal / epidemiology of the candidiasis disseminated neonatal

La candidiasis sistémica neonatal se considera una infección nosocomial, presente en las unidades de cuidados intensivos neonatales, a pesar de los esfuerzos realizados por la comunidad médica para el entendimiento de la fisiopatología y terapéutica de la enfermedad. Se realizó un estudio descriptivo, mixto e inferencial, sobre 705 ingresos de Servicio de Patología Neonatal del Hospital de Niños "J.M de Los Rios", entre enero de 1995 hasta diciembre de 1998. Fueron elegidos 39 recién nacidos con diagnóstico de candidiasis diseminada comprobada por hemocultivo. El análisis estadístico se realizó a travéz de porcentajes, análisis entre diferencias, promedio de porcentajes y aplicación del Chi cuadrado con p<0.05 en las variables en donde fue posible realizar contraste. En el grupo de estudio un 58,9 por ciento de los neonatos tenían un peso menor de 2.500 gr y un 65,8 por ciento eran pretérminos. En su mayoría recibieron antibióticos de amplio espectro (70 por ciento) esteroides, aminofilina, bloqueantes de la secreción gástrica y nutrición parenteral total (60.5 por ciento); presentaron un promedio de estancia prolongada (38,75 días), ameritando ventilación mecánica (79,6 por ciento), catéteres (100 por ciento) y cirugía (30 por ciento). Entre las patologías asociadas destaca la sepsis (82,8 por ciento). El promedio de porcentaje de ingresos correspondió a un 5,27 por ciento y de fallecidos a 10,1 por ciento. La tasa de letalidad fue de 37 por ciento. La candidiasis diseminada está asociada con una alta mortalidad a pesar del tratamiento, por la que la identificacion precoz de los factores de riesgo, un diagnóstico y tratamiento rápidos podría ayudar a reducir la alta letalidad relacionada con esta patología

Efeito da microcistina - LR em rim e intestino isolados e na secreção de insulina / Effect of microcystin - LR in the intestine and kidney and isolated in insulin secretion

A microcistina-LR é uma toxina de cianobactéria amplamente distribuída nos reservatórios de água e que representa grande risco para a saúde de animais e humanos. Neste trabalho avaliou-se o efeito da microcistina-LR em anel de aorta isolado de rato nas doses de 1, 3, 10, 30, 100 e 300 ng/mL, os efeitos renais induzidos por sobrenadante de macrófagos estimulados com esta toxina (1μg/mL), o efeito secretório induzido por microcistina-LR (1μg/mL) e sobrenadante de macrófagos ativados em alça isolada e perfusão intestinal, além da atividade antimitótica e teratogênica da microcistina-LR em ouriço do mar, assim como, a atividade na secreção de insulina utilizando ilhotas de Langerhans isoladas. Observou-se que a toxina não exerceu nenhum efeito no modelo de anel de aorta isolado nas doses utilizadas. Por outro lado, o sobrenadante de macrófagos estimulados com microcistina mostrou-se capaz de alterar de modo significante (*p < 0,05), a pressão de perfusão, resistência vascular renal, fluxo urinário, ritmo de filtração glomerular, percentual de transporte de sódio e percentual de transporte proximal de sódio e potássio no modelo de rim isolado. Os bloqueadores farmacológicos, ciclohexamida (10-5M), dexametasona (10-5M) e quinacrina (10-5M) bloquearam a maioria das alterações renais observadas, enquanto talidomida (1,5 x 10-5M) reverteu apenas o efeito na resistência vascular renal. Estes resultados sugerem que macrófagos estimulados com microcistina-LR liberam mediadores capazes de promover nefrotoxicidade in vitro. Evidenciou-se também que a microcistina-LR assim como, o sobrenadante de macrófagos estimulados com esta toxina, induzem secreção de água e de eletrólitos (sódio, potássio e cloreto) de modo semelhante à toxina da cólera, em alça isolada e perfusão intestinal...

Mecanismo de transporte iônico, em íleo de coêlho, induzido por mecrocistina_LR de microcystis aeruginosa: participação de macrófagos, IL 1 ß, TNF a e mediadores pro-inflamatórios [Manuscrito] / Ion transport mechanism in rabbit ileum induced by Microcystis aeruginosa mecrocistina_LR of: participation of macrophages, IL 1 beta, TNF a and pro-inflammatory mediators [manuscript]

Este trabalho teve-se como principal objetivo, avaliar os efeitos eletrogênicos em preparações de íleo de coelho fixadas em câmaras de Üssing, em presença de sobrenadante de macrófagos (S.MφS) estimulados com microcistina-LR MCLR de Microcystis aeruginosa. S.MφS estimulados com MCLR (3,2. 10-7M; 9,6.10-7M e 3,2.10-6M), produz, de foram dose-dependente; sendo que a variação temporal (t) da corrente de curto-circuito (Isc), pode ser descrita por uma equação do tipo Isc = a. ekt. para um coeficiente de correlação r = 0,9988 e Iscmaximo = 128,16 =- 14,54 μacm-2. Posteriormente, observou-se que os processos metabólicos associados à gênese do fator de " secreção intestinal" (FSI), a partir de macrófagos estimulados, requer a participação de uma proteína G sensível à toxina pertusis ativa. Verificou-se também que inibidores de síntese proteica, proteases, fosfolipase A2, cicloxigenases, lipoxigenases; síntese de TNF-α e antagonista do PAF, reduziram a síntese de FSI. Com o emprego de anticorpos monoclonais, verificou-se que IL-1β era o principal FSI; como também, que macrófagos estimulados com MCLR, nas concentrações acima, reduziu IL-1β e TNF-α, de forma dose-dependente...

Protective effect of L-carnitine on gastric mucosal barrier in rats exposed to cold-restraint stress.

AIM: The protective effect of L-carnitine on stress-induced gastric mucosal injury was investigated in rats exposed to cold-restraint stress (CRS). METHODS: The animals were divided into four groups. Groups 1 and 3 received saline by intragastric gavage for 10 days. Groups 2 and 4 received L-carnitine (50 mg/Kg/day) in the same manner. Groups 3 and 4 were exposed to CRS in the form of immobilization at 4 degrees C for 4 h on day 10. Ulcer index, gastric acid secretion and hemoglobin leakage, and gastric mucosal mucin and PGE2 content were measured. RESULTS: In rats exposed to CRS, as compared to control rats (group 1), ulcer index was higher, gastric acid production was lower, hemoglobin leakage into the gastric lumen was increased, and gastric mucosal mucin and PGE content were reduced. L-carnitine treatment prior to CRS led to attenuation of changes in ulcer index, gastric acid secretion, amount of hemoglobin leakage into the gastric lumen and gastric PGE2 content. In rats receiving L-carnitine but not exposed to CRS, gastric acid secretion, mucin and PGE2 content of gastric mucosa were similar to those in control rats. CONCLUSION: L-carnitine decreases CRS-induced gastric mucosal injury.

Is the intestinal tract a portal of entry for Acanthamoeba infection?

Acanthamoeba culbertsoni isolated from a water sample of El-Mahmoudia canal in Alexandria, was orally inoculated into a mouse model [200-400 amoebae / mouse] under different conditions. One week postinfection [P.I.], 20% of infected normoacidic mice and all animals received cimetidine or tetracycline prior to infection passed the parasite in their stools. One month P.I. 70% of cimetidine and 100% of tetracycline pretreated mice showed marked erosion in the intestinal mucosa and areas of necrosis with congestion in the brains with trophozoites and cysts in both tissues. It is concluded that, normoacidic mice may be simply acting as paratenic hosts. In case of hypoacidity or altered normal flora, the intestinal tract was invaded by amoebae representing a new portal of entry for CNS infection

Evidence for oxidant stress in chronic pancreatitis.

BACKGROUND: Oxidant stress leading to lipid peroxidation is reported to be the common link in the pathogenesis of chronic pancreatitis irrespective of etiology. AIM: To look for evidence of lipid peroxidation in duodenal juice in patients with chronic pancreatitis. METHODS: 19 patients with chronic pancreatitis (14 tropical, 5 alcoholic) and 19 age- and sex-matched subjects with abdominal pain without any cause were studied. Contents were aspirated from the second part of the duodenum during gastroduodenoscopy. Malonyl dialdehyde (MDA) levels were measured in duodenal juice by the thiobarbituric acid method. RESULTS: MDA levels were higher in patients than in the control group (mean [SD] 42.6 [17.0] vs 29.2 [11.7] nmol/mL; p < 0.05). On linear and multiple regression analysis, none of the disease factors correlated with duodenal juice MDA levels. CONCLUSIONS: Lipid peroxidation products are increased in patients with chronic tropical and alcoholic pancreatitis.

Effect of Nelumbo nucifera rhizome extract on the gastrointestinal tract of rat.

Extract of Nelumbo nucifera rhizome (RNN) was used as anti-diarrheal agent to combat the diarrhea in experimental rats. The RNN extract in graded doses (100, 200, 400 and 600 mg/kg body wt.) reduced not only the frequency of defecation, wetness of fecal dropping and PGE2 induced enteropooling but also the propulsive movements of charcoal meal significantly.

Algunas características del tracto gastrointestinal del habitante de las grandes alturas del Perú / Some characteristics of tract gastrointestinal of inhabitant of the altitudes big of Peru

Los habitantes de los Andes peruanos que moran por encima de 3,800 m.s.m.n presentan característicamente: I. Gran frecuencia del dolicomegacolon andino, que se acompaña de estreñimiento, distensión abdominal, elevación del hemidiafragma izquierdo evidenciable radiográficamente y alta incidencia del vólvulo, que constituye la primera causa de obstrucción intestinal en la altura. II. Un débito de secreción ácida gástrica basal mayor que a nivel del mar, con hiperrespuesta a la estimulación; pero alcanzando un débito de secreción gástrica post-estímulo similar al de los individuos del nivel del mar. En la mayor secreción gástrica basal influye, entre otros factores, la hipertonía vagal inducida por la hipoxia y la hipergastrinemía basal encontrada como característica del individuo de altura. En ellos la secreción gástrica disminuye mas tempranamente en relación con la edad y presentan mayor incidencia de úlcera y hemorragia gástrica.

Efeito secretório intestinal do sobrenadante de macrófagos estimulados com a toxina A do clostridium difficile: papel da interleucina-1B / Effect Intestinal secretory macrophages stimulated with supernatant Clostridium difficile toxin A: role of interleukin-1B

O Clostridium difficile produz duas exotoxinas denominadas toxina A (TxA; 308 kDa) e toxina B (TxB; 279 kDa). O modo de ação intestinal dessas toxinas ainda é pouco compreendido, não obstante vários trabalhos científicos confirmarem seu envolvimento na patogênese de doenças diarréicas inflamatórias. No início desse estudo foi determinado o efeito secretório intestinal induzido pelo sobrenadante de macrófagos estimulados com TxA ou TxB, no íleo de coelho montado em câmaras de Üssing. A partir desse protocolo, observou-se que o sobrenadante de macrófagos estimulados com TxA (3,2x10-7M, 9,6x10-7M e 3,6x10-6M) causa secreção intestinal (ΔIsc = 41,0, 52,0 e 99,0 μA.cm-², respectivamente). Entretanto, o sobrenadante de macrófagos tratados com TxB (3,6x10-7M) não alterou de forma significativa essa atividade (ΔIsc = 28,0 μA.cm-² vs ΔIsccontrole = 20,0 μA.cm-²). Vale salientar que a adoção de TxA (3,2x10-6M) diariamente nas câmaras de Üssing não produziu secreção intestinal (ΔIsc = 2,2 μA.cm-²). Ademais, a gênese do fator de secreção intestinal (FSI), presente neste sobrenadante, foi bloqueada (80%) pela incubação de TxA com o PCG4. Na etapa seguinte, investigou-se o envolvimento de proteína G na gênese do FSI, através do tratamento prévio dos macrófagos com a toxina pertussis ativa. Daí, evidenciou-se que esse procedimento é capaz de bloquear a liberação do FSI (bloqueio: 61%). A seguir, avaliou-se o efeito de vários bloqueadores farmacológicos sobre a síntese do FSI. Assim, foi observado que inibidores específicos, como por exemplo, inibidor de síntese protéica (67%), proteases (57%), fosfolipase A2 (54%), ciclooxigenase (62%), ciclo e lipoxigenase (48%), síntese de TNF-α (48%) e antagonista de PAF (55%), reduzem a síntese e liberação do FSI...

cAMP-dependent signalling is involved in adenosine-stimulated Cl- secretion in rabbit colon mucosa

An important property of the intestine is the ability to secrete fluid. The intestinal secretion is regulated by a number of substances including vasoactive intestinal peptide (VIP), ATP and different inflammatory mediators. One of the most important secretagogues is adenosine during inflammation. However, the controversy concerning the underlying mechanism of adenosine-stimulated Cl- secretion in intestinal epithelial cells still continues. To investigate the effect of adenosine on Cl- secretion and its underlying mechanism in the rabbit colon mucosa, we measured short circuit current (ISC) under automatic voltage clamp with DVC-1000 in a modified Ussing chamber. Adenosine, when added to the basolateral side of the mucosa, increased ISC in a dose-dependent manner. The adenosine-stimulated ISC response was abolished when Cl- in the bath solution was replaced completely with gluconate. In addition, the ISC response was inhibited by a basolateral Na-K-Cl cotransporter blocker, bumetanide, and by apical Clchannel blockers, dephenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), glibenclamide. Amiloride, an epithelial Na+ channel blocker, and 4,4-diisothiocyanato-stilbene-2,2-disulphonate (DIDS), a Ca2+-activated Cl- channel blocker, had no effect. In the mucosa pre-stimulated with forskolin, adenosine did not show any additive effect, whereas carbachol resulted in a synergistic potentiation of the ISC response. The adenosine response was inhibited by 10 micrometer H-89, an inhibitor of protein kinase A. These results suggest that the adenosine-stimulated ISC response is mediated by basolateral to apical Cl- secretion through a cAMP-dependent Cl- channel. The rank order of potencies of adenosine receptor agonists was 5'-(N-ethylcarboxamino)adenosine(NECA) > N6-(R-phenylisopropyl)adenosine(R-PIA)>2-(p-(2-carbonylethyl)-phenyl-et hylamino)-5'-N-ethylcarboxaminoadenosine(CGS21680). From the above results, it can be concluded that adenosine interacts with the A2b adenosine receptor in the rabbit colon mucosa and a cAMP-dependent signalling mechanism underlies the stimulation of Cl- secretion.

The lysine-1 analog of guanylin induces intestinal secretion and natriuresis in the isolated perfused kidney

Guanylin is an endogenous peptide synthesized by several mammalian species that mimics the effects of a thermostable enterotoxin of Escherichia coli (STa: NTFYCCELCCNPACAGCY) in the gut. We have cloned a lysine-1 derivative of rat guanylin (Lys-1-NTCEICAYAACTGC) and tested its effects on ileal tissue membranes in Ussing chambers and in the isolated perfused rat kidney. Rabbit ileal mucosa membranes were mounted into a Ussing chamber and the effects of Lys-1 guanylin (Lys-1 G) and STa enterotoxin peptide on chloride secretion were determined by changes in short-circuit current (Isc). Lys-1 G (10 to 100 nM) showed a dose-dependent effect on chloride secretion with a maximal response estimated to be 52 microA/cm2. Lys-1 G mimics the effect of STa peptide, but the enterotoxin elicited a greater maximal effect of 120 microA/cm2 (p<0.01). Lys-1 G (2.5 microg/ml) promoted an increase in both urine flow (from 0.13 +/- 0.07 to 0.40 +/- 0.01 ml g(-1) min(-1), N = 4; P<0.05) and glomerular filtration rate (from 0.68 +/- 0.02 to 0.85 0.00 ml g(-1) min(-1), N = 4; P<0.01) in the isolated perfused kidney and a reduction of the fractional reabsorption of sodium (from 76.0 +/- 0.03 to 59.5 +/- 0.85 percent, N = 4; P<0.01). These maximal effects were accompanied by intense natriuretic effect observed 30 and 60 min after drug administration. The Lys-1 G analog similar to STa enterotoxin elicited intestinal chloride secretion and a natriuretic effect. These data demonstrate that the cloned peptide analog retains the biological activity of the native hormone and presents activity similar to STa. The properties of Lys-1 G resemble those of a factor formed during perfusion of the hypoxic rabbit kidney and named by us factor natriureticus similis (FNS).