Regional difference of endogenous ATP release in the pulmonary artery of rabbits

1. The release of adenyl purines such as ATP, ADP, AMP and adenosine, from the pulmonary artery trunk (PAT), extrapulmonary artery (EPA) and intrapulmonary artery (IPA) were compared. 2. The amount of basal overflow of adenyl purines from the PAT was significantly smaller than those from EPA and IPA. There was no significant difference between the amount of the overflow from EPA and PAT. 3. Methoxamine, an alpha 1-adrenoceptor agonist, significantly increased the overflow of adenine nucleotides from the PAT, EPA and IPA, but did not increase those of adenosine. Methoxamine-induced release of adenyl purines from IPA was significantly larger than those from EPA and PAT. 4. These results suggest that an alpha 1-adrenoceptor-mediated mechanism for ATP-release is not homogeneously distributed in the pulmonary artery and a larger amount of ATP may be released in the peripheral part of the artery.

Intra-arterial administration of the angiogenesis inhibitor TNP-470 blocks liver metastasis in a rabbit model

We evaluated the best route of administration of TNP-470, an angiogenesis inhibitor, by comparing the anti-tumour effects and toxicity following injection via the hepatic artery, the portal vein, or the jugular vein in a rabbit model of liver metastases. Following the injections of 1 x 10(6) VX2 carcinoma cells into the portal vein of rabbits, 50 mg of TNP-470 was injected continuously into the hepatic artery, portal vein, or jugular vein for 7 days. The number of tumours on the surface of the liver was counted 14 days following the start of the infusion, and the serum glutamic-oxaloacetic transamine (GOT), glutamic-pyruvic transaminase (GPT) and total bilirubin concentrations were examined. In addition, a coloured silicon rubber was injected into the vessels of the liver to visualise the capillary networks around the tumours and assess the degree of suppression of angiogenesis by TNP-470. The mean number of tumours following intra-arterial injection (17.5 +/- 2.9) was significantly less than the control (237.0 +/- 34.0) (P < 0.05). The mean numbers of the tumours following intraportal (89.1 +/- 16.0) and intravenous (140.6 +/- 31.2) injection were both less than the controls (215.3 +/- 45.5, 284.8 +/- 55.4 respectively), but the differences were not significant. We conclude that intra-arterial injection of TNP-470 is the most effective method for preventing liver metastases in this model.

Rat kidney thromboxane receptor: molecular cloning, signal transduction, and intrarenal expression localization

Thromboxane (TX) plays important roles in control of renal hemodynamics and water and electrolyte metabolism, and is involved in the pathophysiology of many renal diseases. The aim of the present study is to isolate a rat kidney cDNA encoding functional TX receptor, and to reveal its intrarenal expression localization. A clone (rTXR2) was isolated from a rat kidney cDNA library by a homology screening approach. rTXR2 was shown to encode the amino acid sequence containing seven transmembrane spanning domains representing rat (r) TX receptor. The membrane from COS-7 cells transiently transfected with rTXR2 cDNA was shown to be specifically bound by a thromboxane receptor antagonist, SQ29548. Either in Xenopus oocyte expression or in transfected COS-7 cells, rTX receptor was shown to be linked with Ca2+ messenger system. TX receptor-mediated increase in cytosolic Ca2+ was also observed in cultured glomerular mesangial cells. In situ hybridization showed that rTX receptor mRNA was detected in renal glomeruli, smooth muscle cells in renal arterioles, and transitional cell epithelium of renal pelvis. Reverse transcription linked to PCR applied to microdissected nephron segments indicated the presence of rTX receptor mRNA exclusively in the glomerulus. In conclusion, we have cloned a functional rat kidney TX receptor, which is expressed specifically in renal glomerulus, arterial smooth muscle cells, and transitional cell epithelium of renal pelvis. The present study will provide important insights into the etiology and pathophysiology of renal diseases with relation to TX metabolism.

Comparison of the entire nucleotide and deduced amino acid sequences of the attenuated hog cholera vaccine strain GPE- and the wild-type parental strain ALD

We have determined the complete nucleotide sequences of a live attenuated hog cholera virus (HCV) and its progenitor strain. The viral RNA of each strain consisted of 12,298 nucleotides including untranslated regions of 373 and 228 bases at the 5' and 3' end, respectively. There was a single large open reading frame spanning 11,697 nucleotides which could encode a large protein of 3,899 amino acids with a calculated molecular weight of 438-kDa. We have found 225 nucleotide difference between the two strains, of which six were located in the untranslated region. Four-sixths of these differences resulted in amino acid substitutions.

[Fructose 1,6-diphosphate can be a substrate to accelerate glycolysis]

Fructose 1,6-diphosphate (F1, 6P) is a glycolytic intermediate which has already been used clinically to treat congestive heart failure. F1, 6P has been shown experimentally to improve glycolytic flux, although theoretical background is unclear. Since there is two possible mechanism of F1, 6P effect on acceleration of glycolysis, including pharmacological effect and substrate effect, we sought to determine the real mechanism of action of F1, 6P on glycolysis. Langendorff-perfused rabbit hearts were infused with F1, 6P (5 and 10 mM) in a first group, and in a second group, 30 minutes of perfusion with modified Krebs-Henselit (K-H) buffer with reduced glucose concentration (5 mM), plus 2-deoxy glucose (5 mM) and with or without 10 mM F1, 6P followed by 30 minutes of wash with normal K-H buffer. We measured contractile function, oxygen consumption, and high energy phosphate by 31p-NMR spectroscopy. In the first group of experiments, F1, 6P resulted in a dose dependent increase in high energy phosphate production and inorganic phosphate (Pi). There was also a marked decline in developed pressure (Dev P) due mostly to the ability of F1, 6P to chelate calcium. Intracellular Mg2+ which was also reduced during F1, 6P infusion might be related to intracellular Ca2+ and/or accelerated glycolysis. In the model of glycolysis inhibited by 2-DG, Dev P was consistently decreased during the infusion of 2-DG, and wash-out period along with the deterioration of high energy phosphate. However, F1, 6P could provide excellent recovery of contractile function after wash along with superior high energy potential during the 2-DG infusion and wash.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct detrimental effects of L-arginine upon ischemia--reperfusion injury to myocardium

The effects of L-arginine on recovery of myocardial contractile function and oxidative metabolism were investigated in a model of reversible global normothermic, ischemic injury using an isolated, buffer-perfused rabbit heart preparation. One mM L-arginine was infused into hearts for 2 min at the onset (group 1) of a 35 min period of ischemia or at the onset of reperfusion (group 2). In non-ischemic hearts, L-arginine caused a slight increase in developed pressure but had no effects on diastolic pressure, oxygen consumption (MVO2), coronary flow, or lactate production. When administered either before or after ischemia-reperfusion. L-arginine caused a significant increase in the diastolic pressure-volume relationship (PVR) and decline in systolic function when compared to untreated control hearts receiving the same ischemic injury. Recovery of MVO2 and high energy phosphates (phosphocreatine and ATP), measured by 31P-NMR spectroscopy, were significantly impaired in L-arginine-treated hearts compared to reperfused control hearts. Lactate release on reperfusion was also higher in both arginine-treated groups. Nitric oxide release into the coronary circulation (measured in separate experiments by the conversion of [15N]L-arginine to [15N]nitrate/nitrite using gas chromatography/mass spectroscopy) was not increased by L-arginine administration. Thus, we conclude that L-arginine acts synergistically with ischemia reperfusion to augment myocardial injury, which includes inhibition of oxidative metabolism and mitochondrial function.

An adult diagnosed as hyper-IgM immunodeficiency syndrome

A 27-year-old male who visited our hospital because of pneumonia was diagnosed as hyper-IgM immunodeficiency syndrome. His serum IgM level was markedly elevated, while the serum level of IgD was normal with a markedly decreased level of serum IgG and IgA. The proportion of T and B cells of peripheral blood lymphocytes was normal. However, B cells bearing surface IgG or IgA were not detectable by immunofluorescence technique. There was a consanguineous marriage in his family, suggesting that his disorder was caused by a genetic abnormality such as X-linked recessive and also autosomal recessive inheritance, although further study is necessary. CD40 ligand cDNA did not appear to contain any abnormal changes within the coding region.

Characterization of the facilitatory prejunctional purinoceptor on adrenergic nerves of the rabbit ear artery

The effects of a number of purinoceptor agonists and antagonists on the release of endogenous norepinephrine (NE) from electrically field-stimulated (2 ms, 4 Hz) rabbit ear arteries were determined. NE was quantified by high-performance liquid chromatography and electrochemical detection techniques. Both P1- and P2-purinoceptor agonists enhanced the release of NE in a concentration-dependent manner (0.1 microM-100 microM), the relative order of potency being beta, gamma-methylene ATP (beta gamma-mATP) > 2-chloroadenosine (2CA) > ATP > L-phenylisopropyl-adenosine > 2-methylthio ATP > 5'N-ethylcarboxamido-adenosine. Adenosine and alpha, beta-methylene ATP (alpha beta-mATP) at 100 microM did not significantly enhance the electrical field stimulation-evoked release of NE. None of drugs changed the spontaneous overflow of NE. Pretreatment with alpha beta-mATP (1, 10 microM), a P2x-purinoceptor desensitizing agent, and 8-sulfophenyl theophylline (8SPT; 1 and 10 microM), a P1-purinoceptor antagonist, caused a shift to right of the concentration-release curve for beta gamma-mATP. alpha beta-mATP and 8SPT did not by themselves significantly affect the spontaneous overflow and the electrical field stimulation-evoked release of NE. Pretreatment of alpha beta-mATP (30 microM) and 8SPT (30 microM) antagonized facilitation of NE release by 2CA (10 microM). The concentration-contraction curve for beta gamma-mATP (1-300 microM) in the rabbit ear artery was shifted to the right by alpha beta-mATP (30 microM) but not by 8SPT (30 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological study on the dry distillation tar of delipidated soybean (Glyteer) (5): Antimicrobial activity]

Glyteer (GL) possessed a broad antimicrobial spectra against bacteria and fungi. The antimicrobial activity of GL was bactericidal action, but not bacteriostatic action. GL was more effective against fungi than bacteria. GL ointment also showed antimicrobial activity equal to that of GL. Furthermore, GL had an effect on methicillin-resistant Staphylococcus aureus (MRSA). Resistance to GL was not induced in broth cultures of Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, Candida albicans, and Trichophyton mentagrophytes. These results suggest that GL applied externally exerts a potent effect as an anti-microbial drug for dermopathy with various microbialpathogens.

Arteriovenous malformation associated with a large cyst--case report

A 37-year-old male presented with an arteriovenous malformation in the left temporal lobe associated with a large cyst. The cyst was drained and the nidus completely excised. The histological findings suggest that repeated subclinical hemorrhages from neovascular channels of the cyst membrane was responsible for the growth of the cyst.

Establishment of a new human cell line, LI90, exhibiting characteristics of hepatic Ito (fat-storing) cells

BACKGROUND

Thus far, human hepatic Ito (fat-storing) cell lines have not been established. Therefore, functional characteristics of Ito cells have not been fully investigated.

EXPERIMENTAL DESIGN

We established a new cell line, LI90, that exhibited characteristics compatible with those of Ito cells from a human hepatic mesenchymal tumor. LI90 cells were examined with phase-contrast microscopy, immunohistochemistry, and cytogenetics, and their vitamin A-storing activity was analyzed. To obtain a marker specific for Ito cells for immunohistochemical analyses, we raised mAb against LI90 cells and clarified the molecular nature of the Ag recognized with the new Ab using an expression cloning approach.

RESULTS

LI90 cells showed polygonal shape and had well developed alpha-smooth muscle actin filaments in their cytoplasm. In an overconfluent culture condition, LI90 cells aggregated to form a typical hills-and-valleys structure, LI90 cells produced various connective tissue components, such as collagen types I, III, IV, V, and VI, laminin, and fibronectin. In culture media containing vitamin A, LI90 cells formed many fat droplets in their cytoplasm, and fluorescence characteristic of vitamin A was observed in the droplets. By immunizing mice with LI90 cells, three separate mAb specifically reacting with Ito cells in human liver sections were established, and the Ag recognized with all three Ab were identified as extracellular matrix tenascin.

CONCLUSIONS

The above-described morphologic and functional characteristics, including vitamin A-storage and biosynthesis of tenascin, are compatible with those of Ito cells. Therefore, LI90 cells will be useful for in vitro studies of functions of human Ito cells.

Twenty-four hour monitoring of pH in the gastric tube replacing the resected esophagus

BACKGROUND

Peptic ulcers in the gastric tube replacing the resected esophagus develop silently and cause serious problems. In this study, the acidity of the gastric tube was examined by 24-hour pH monitoring to determine if the acidity of the gastric tube was sufficient to cause peptic ulcers.

STUDY DESIGN

The acidity of a gastric tube was evaluated by 24-hour pH monitoring of both the fundus and the antrum in 55 patients treated for carcinoma of the esophagus. The correlation between the fasting serum gastrin concentration and the intraluminal acidity of the completely vagotomized gastric tube was examined.

RESULTS

In the patients with high postoperative acidity in the fundus or the antrum (46 percent of the 41 patients examined), the intraluminal pH remained consistently low, even long after operative treatment. Significant correlations existed between the percentage of time that the pH remained below 3 preoperatively and postoperatively in both the fundus and the antrum (r = 0.4777, p = 0.0386, and r = 0.7597, p = 0.0002, respectively). The percentage did not decrease significantly postoperatively. A significantly negative correlation (r = -0.783401, p < 0.0001) was found between the fasting serum gastrin level and the proportion of time that the nocturnal pH in the antrum remained below 3.

CONCLUSIONS

Even long after esophagectomy, the pH of the gastric tube is low enough to cause peptic ulcers, especially in patients with high preoperative acidity. In these patients, the intraluminal pH in the antrum of the gastric tube correlates inversely with the fasting serum gastrin level.

An angiotensin II receptor antagonist attenuates left ventricular dilatation after myocardial infarction in the hypertensive rat

OBJECTIVE

The aims were (1) to investigate the effect of hypertention on left ventricular dilatation and haemodynamic alterations following acute myocardial infarction in spontaneously hypertensive rats (SHR) and normotensive rats (WKY); (2) to compare haemodynamic indices between the two groups; (3) to assess whether the angiotensin II type 1 receptor antagonist (AIIA), TCV-116, prevented left ventricular dilatation after myocardial infarction; and (4) to compare the effect of AIIA with that of the angiotensin converting enzyme (ACE) inhibitor, delapril.

METHODS

Myocardial infarction was produced in SHR and WKY by coronary artery ligation. Haemodynamic measurements were obtained three weeks later in rats that had been treated from the next day after the operation for three weeks with TCV-116 (1 mg.kg-1.d-1) or delapril (1 g.litre-1 in drinking water), and in untreated controls.

RESULTS

After myocardial infarction, left ventricular weight, and left ventricular weight were greater in SHR than in normotensive rats. Right ventricular weight, left ventricular end diastolic pressure, and LVEDVI correlated positively with infarct size in both SHR and WKY and these slopes were steeper in SHR than in WKY (P < 0.05). TCV-116 and delapril each significantly attenuated the increases in left ventricular end diastolic pressure, left ventricular weight, right ventricular weight, and LVEDVI following myocardial infarction in both in WKY and SHR, and shifted pressure-volume curve significantly to the left.

CONCLUSIONS

Hypertension accelerates left ventricular dilatation and haemodynamic alterations following myocardial infarction in rats. These effects are attenuated by an angiotensin II type 1 receptor antagonist as well as by an ACE inhibitor.

Shortening of the hippocampal formation in first-episode schizophrenic patients

Shortening of hippocampal formation (HF) in chronic schizophrenic patients have been demonstrated in our previous study. The purpose of the present study is to test if shortening of the HF occurs in schizophrenic patients suffering their initial psychotic episode. We performed contiguous, 1 mm thick, magnetic resonance imaging scans in 20 first-episode schizophrenic patients, 21 chronic schizophrenic patients, and 25 healthy subjects. Both groups of schizophrenic patients demonstrated significant shortening of the HF compared with normal controls (first-episode schizophrenia, 5.3%; chronic schizophrenia, 8.0%). However, the HF length was not significantly different between the first-episode and chronic schizophrenic patients. No significant correlation was seen between the HF length and the duration of illness in chronic schizophrenic patients. These results suggest that the HF shortening observed in schizophrenic patients may be genetic and/or developmental in origin.

[Improved protection of hypertrophied myocardium in ischemia by histidine buffer cardioplegia]

Pressure overload hypertrophy has been known risk factor for open heart surgery, because of accelerated loss of high energy nucleotides, greater accumulation of H+ and lactate, and earlier onset of contracture. To test the efficacy of histidine containing cardioplegia (HB) on promotion of anaerobic glycolysis leads to improved preservation of hypertrophied heart, hypertrophied rabbit heart (aortic banding at 10 days) received HB or high potassium Krebs buffer solution (KCl) were subjected to 40 min of 37 degrees C ischemia followed by reperfusion in an isolated Langendorff mode. There was significantly higher phosphocreatine, intracellular pH and lactate production which was an indicator of anaerobic glycolysis and better recovery of cardiac function in HB group compared to KCl group. We concluded that histidine containing cardioplegia was able to promote anaerobic glycolysis to maintain high energy phosphates as well as contractile function in hypertrophied myocardium.

Parainfluenza virus type 1 infects olfactory neurons and establishes long-term persistence in the nerve tissue

A mouse model of Sendai virus infection was adopted to examine the in vivo neurovirulence of parainfluenza viruses. A nested polymerase chain reaction detected the Sendai virus nucleoprotein gene in the olfactory bulbs of intranasally infected mice for at least 168 days post-infection (p.i.) and virus-specific messenger RNAs for 28 days p.i. Viral proteins were histochemically detected in some olfactory neurons for 7 days p.i. They were also found in glomeruli of the olfactory bulbs but not in the mitral cells and the tufted cells. No virus was detected in the whole brain not including the olfactory bulbs. When mice were inoculated with UV-inactivated virus, the viral RNA was present in the olfactory bulbs for a short period of 14 days, with no demonstrable viraemia. These results demonstrate that the parainfluenza virus directly accesses the central nervous system via olfactory neurons and establishes long-term persistence in the nerve tissue.

Nucleotide sequence of the gene encoding novel delta-endotoxin from Bacillus thuringiensis serovar japonensis strain Buibui specific to scarabaeid beetles

A new isolate of Bacillus thuringiensis serovar japonensis strain Buibui, which was specific to scarab beetles (M. Ohba et al., Lett. Appl. Microbiol. 14:54, 1992), was shown to have a 130-kDa insecticidal crystal protein (ICP) (H. Hori et al., J. Appl. Bacteriol. 76:307, 1994). ClaI restriction enzyme fragments of total cell DNA of the isolate were cloned into E. coli (Sato et al., Curr. Microbiol. 28:15, 1994). Whole 3480-bp nucleotide sequence of the gene encoding 130-kDa ICP was determined, and the molecular weight of the ICP was estimated to be 130,424. The strongly conserved five blocks that occur in almost all ICP genes of B. thuringiensis were detected in the ORF with the same order and almost the same intervals as elsewhere. The amino acid sequence homologies of the whole ICP or N-terminus half portion to that of the CryIIIA, B, C, D, and CryV were about 35%.

[A case of incarceration of a right femoral hernia in a very old female with a intriguing clinical course]

The patient was a 94-year-old woman. She was admitted on our hospital for ileus due to incarceration of a right femoral hernia on October 29, 1993. Although an emergency operation was necessary she refused, therefore we continued to have conservative therapy. After repeated persuasion, she agreed the operation which was performed under spinal anesthesia on November 17. The peritoneal cavity was opened through a transverse incision of the lower abdomen. Some bloody ascites was encountered. Part of the jejunum was incarcerated through right femoral canal and was completely obstructed, with ischemic but no necrotic changes. It was excised. She resumed oral intake on the 7th postoperative day and was discharged on the 77th postoperative day. Initially due to her opposition we could not perform the operation, but after persistent persuasion she agreed and survived. Good communications between the doctor and the patient, and of course informed consent, was very important in such cases.

In vivo angioscopic detection of the damaged endothelium on the atheromatous plaque: application with vital staining by methylene blue

We attempted to detect the lesion of the damaged endothelium on the atherosclerotic plaque in vivo with dye and angioscope. The plaques were induced on the aortae of rabbits by the continuous mechanical injury with the insertion of the polyethylene tube and feeding with 2% cholesterol-added diet. We observed the some plaques could be stained with 5 x 10(-2) mol/L methylene blue by angioscope. Control aorta, without any stimulations on the aorta, could not be stained. One month after injury and cholesterol feeding the plaques were stained. In such plaques, the lack of the endothelium and the existence of the lipid-containing cell in the intima was observed. However, the plaques of the aorta 6 months after finishing these procedures could not be stained. In these plaques, the morphological characteristics known as the regression of the atheromatous plaque, ie, the regeneration of the endothelium, the thick collagen layer on the plaque and the massive calcification of the plaque were observed. The results obtained were as follows. (1) The atheromatous lesion with the damaged endothelium could be detected in vivo by our vital staining method. (2) The atheromatous plaques stained in vivo are the lesion with complication and enhanced permeability. (3) The slightly stained plaques indicate the lesions with regression and lost high permeability. (4) Our method would be able to add important information on the atheroscrelotic lesions in the clinical situations than that now we perform.

Desensitization of capsaicin-sensitive sensory neurons in rat stomachs on chronic treatment with sodium taurocholate

We examined the effects of chronic treatment with 10 mM sodium taurocholate (TC) on gastric functions, capsaicin-sensitive afferent neurons and the gastric mucosa in male rats. Stomachs were mounted in Lucite chambers, and then the transmucosal potential difference (PD), luminal pH and gastric mucosal blood flow (GMBF) in response to TC or capsaicin was determined. In normal animals, 10 mM TC caused a reduction in PD, and increases in luminal pH and GMBF. Capsaicin (1 mg/ml) produced an apparent increase in GMBF without any change in PD or luminal pH. After 4- or 12-week treatment with TC, the basal PD was significantly reduced, and the luminal pH tended to increase. The increase in GMBF in response to TC or capsaicin was profoundly suppressed in TC-pretreated animals. The calcitonin gene-related peptide release in response to capsaicin was significantly reduced after 4 weeks treatment with TC. There were no microscopical changes in the oxyntic mucosa until 4 weeks after TC treatment except for exfoliation of surface cells. However, an increase in inflammatory cell infiltration was observed 12 weeks later. We conclude that chronic treatment with TC causes desensitization of capsaicin-sensitive afferent neurons and reduces GMBF, which may result in the production of gastritis.

[Reticulated platelets--automated measurement and clinical utility]

Development of the method to determine reticulated platelets is briefly reviewed. A new rapid method to automatically count reticulated platelets is very recently established by our research group. The principle of the measurement of reticulated platelets is based on flow cytometry. The platelets are quickly stained with a RNA fluorescent dye, auramine O and fluorescent intensity (RNA content) and forward scatter (cell size) are measured in only 80 seconds with a reticulocyte counter, equipped with special software for analysis of reticulated platelets. Both of the reproducibility and the linearity were shown to be good. Normal percentage value for reticulated platelets was 0.98% +/- 0.41% and its absolute count was 2.12 +/- 0.69 x 10(9)/l. The absolute count was decreased in patients with reduced thrombopoiesis such as acute myeloblastic leukemia, aplastic anemia and was elevated in patients with essential thrombocythemia and in chronic myelocytic leukemia. The patients with chronic idiopathic thrombocytopenic purpura had a high percentage of reticulated platelets. An apparent rise was noticed in the percentage of reticulated platelets which preceded by several days a progressive increase in the platelet count at the recovery phase of thrombocytopenia in a couple of leukemic patients. These suggest that an automated measurement of reticulated platelets can be clinically useful to estimate thrombopoiesis in bone marrow.

Mechanism of gastric alkaline response in the stomach after damage. Roles of nitric oxide and prostaglandins

The gastric mucosa responds to hypertonic NaCl by significantly decreasing acid secretion. We examined the role of nitric oxide (NO) in this phenomenon in comparison with endogenous prostaglandins (PGs). A rat stomach was mounted in an ex vivo chamber, perfused with saline, and the potential difference (PD), pH, and acid/alkaline responses were measured before and after the application of hypertonic NaCl (1 mol/liter) with or without pretreatment with NG-nitro-L-arginine methyl ester (L-NAME; an inhibitor of NO biosynthesis) or indomethacin (a cyclooxygenase inhibitor). NaCl at 1 M caused a PD reduction, a decrease in acid secretion, and an increase in luminal HCO3-. Prior administration of L-NAME (5 mg/kg, intravenously) as well as indomethacin (5 mg/kg, subcutaneously) did not affect PD and HCO3- responses, but significantly attenuated the inhibitory effect of 1 M NaCl on acid secretion, although the effect of L-NAME was more potent when compared to indomethacin. This effect of L-NAME was antagonized by the simultaneous administration of L-arginine but not by D-arginine (200 mg/kg, intravenously), whereas the effect of indomethacin was completely reversed by PGE2 (100 micrograms/kg, intravenously). The histamine-stimulated acid secretion in the normal stomach was significantly decreased by nitroprusside (the exogenous NO donor; 4 mg/kg, intravenously) and PGE2, but not by either L-NAME or indomethacin. These results suggest that in addition to PGs, NO is involved in the mechanism of the gastric alkaline response after damage with 1 M NaCl. Irritation of the gastric mucosa by hypertonic NaCl may release endogenous NO and PGs, both of which in turn inhibit acid secretion and unmask luminal alkalinization due to HCO3- flux in the damaged portion.