Residues interacting with serine-174 and alanine-295 in the beta-subunit of Escherichia coli H(+)-ATP synthase: possible ternary structure of the center region of the subunit

The mutation of serine-174 to phenylalanine that causes a defect in the Escherichia coli F1-ATPase beta-subunit is suppressed by further mutations; Gly-149 to Ser, Ala-295 to Thr, Ala-295 to Pro, or Leu-400 to Gln (Miki, J., Fujiwara, K., Tsuda, M., Tsuchiya, T. and Kanazawa, H. (1990) J. Biol. Chem. 265, 21567-21572). We analyzed the effects of these second site mutations and of a newly identified Asn-158 to Tyr mutation on the activities of the ATPase without the original Ser-174 to Phe mutation. The beta-subunit with each amino acid replacement was expressed in the mutant strain JP17, which does not have a beta-subunit. Cells transformed with the plasmid carrying Ala-295 to Pro mutation alone did not grow on minimal medium agar supplemented with succinate as the sole carbon source, and showed 3% of the wild-type ATPase activity, suggesting that this mutation caused structural alterations affecting the catalytic function of the enzyme. Conversely transformants with other mutations grew well and had higher ATPase activities, suggesting that these mutations did not cause extensive structural alterations. From the transformants with the plasmid carrying the Ala-295 to Pro mutation, seven revertants capable of cell growth on succinate plates were isolated and reversion mutations were identified at residues 140, 159, 166, 171, 172 and 184 of the beta-subunits. The results suggested that Ser-174 and Ala-295 do not necessarily interact directly, but that the regions including these suppression mutation sites close to Ser-174, and Ala-295 interact with each other for the proper functioning of the ATPase. The ternary structure of the region surrounded by the residues which were identified as the reversion mutation sites for Ser-174 to Phe and Ala-295 to Pro mutations is important for the catalytic function of this enzyme.

High-performance liquid chromatographic determination of catecholamine metabolites and 5-hydroxyindoleacetic acid in human urine using a mixed-mode column and an eight-channel electrode electrochemical detector

An HPLC system for the simultaneous determination of acidic catecholamine metabolites, related compounds and 5-hydroxyindoleacetic acid (5-HIAA) in human urine was developed. A mixed-mode (C18/anion-exchange) column with isocratic elution using citrate buffer and an eight-channel electrochemical detector were used. Vanilmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenyllactic acid (vanillactic acid, VLA), homovanillic acid (HVA), vanillic acid (VA) and 5-HIAA in urine were determined simultaneously. Detection limits and inter (n = 5) and intra-assay (n = 5) coefficients of variation were satisfactory. The mean of analytical recoveries (n = 3, +/- C.V. (%)) were between 97 +/- 3.2 (VMA) and 105 +/- 4.8 (VA). Correlations between the analytical results for VMA, HVA and 5-HIAA obtained by an established method and the present method were satisfactory. The mean +/- 2 S.D. of the excretion rates of VMA, DOPAC, VLA, HVA, 5-HIAA and VA in urine from healthy adult volunteers were 0.61-4.36, 0.13-1.02, 0-0.35, 0.67-6.55, 0.50-5.14 and 0-0.55 mg/g creatinine, respectively.

Reversion mutations in the beta subunit mutants of Escherichia coli F1-ATPase with defective subunit assembly: implications for structure and function of the amino-terminal region

We analyzed reversion mutations of the mutants with a substitution of Leu-40 by Pro or Glu-41 by Lys in the beta subunit of Escherichia coli F1-ATPase. These mutants had an altered molecular assembly of the alpha and beta subunit on the membranes and lost the binding activity of the beta subunit to the monoclonal antibody beta 31. For the mutation of Leu-40 to Pro, we found that all reversion mutations Gln, or Ser besides the wild-type Leu. These pseudo reversion mutations restored the cell growth on minimal agar supplemented with succinate as the sole carbon source, the assembly of the alpha and beta subunits, and also the ATPase activities in the membranes. These results suggested that Leu-40 itself is not an essential residue for the function of the beta subunit but that the residue contributes to a conformation around residue 40, which is important for the assembly of the alpha and beta subunits onto the membranes. For the mutation of Glu-41 to Lys, pseudo reversion mutations were found at the original residue 41 as Lys to Gln or Asn and also at Arg-218 to Cys or His in addition to the original Glu-41 to Lys mutation. These suppression mutations recovered the cell growth, indicating the recovery of ATP synthesis. The ATPase activity was high in cells with the Lys-41 to Glu mutation but those were relatively low in those with other reversion mutations. The assembly of the alpha and beta subunits recovered in the revertants to the wild-type level, except for the Lys-41 to Asn mutation, which resulted in a decreased amount of the alpha subunit on the membranes. These results suggested that though Glu-41 is not an essential residue, it plays an important role in the assembly of the alpha and beta subunit on the membranes. The results also suggested that residues Arg-218 and Glu-41 are located close together and interact with each other, either directly or indirectly.(ABSTRACT TRUNCATED AT 400 WORDS)

Total circular annuloplasty with absorbable suture for the repair of left atrioventricular valve regurgitation in atrioventricular septal defect

To obtain a better control of left atrioventricular valve regurgitation, we applied total circular annuloplasty with the use of absorbable sutures to 14 children with atrioventricular septal defect (six complete forms and eight incomplete forms). In the intraoperative period, a good coaptation of the leaflets was achieved and the regurgitation was minimized or disappeared. Follow-up studies with echocardiography for 13 survivors showed a gradual increase of annular size during the postoperative period. Ten patients of the survivor group (77%) maintained good valvular competency in a long-term period. Total circular annuloplasty is a simple and effective procedure to reduce the regurgitation and prevent the annular dilatation during the immediate postoperative period.

[Simultaneous determination of catecholamines, serotonin, and their precursors and metabolites in body fluid by an HPLC system with multi-electrode electrochemical detector]

We have developed two HPLC systems for the simultaneous determination of CA, 5-HT and their precursors and metabolites in human body fluid. One system consisted of two reversed-phase columns, a column switching device, a pair of electrodes for elimination of interferents and two sets of new electrochemical detectors with four electrodes. Using this system, adequate separation of peaks for 17 kinds of CA, 5-HT and their related metabolites in a standard solution required only 17 min. NE, MHPG, DOPAC, 5-HIAA, HVA and TRP levels in cerebrospinal fluid (CSF) were determined without any pretreatment of the CSF samples. The concentrations of DOPAC, 5-HIAA and HVA in CSF were significantly lower in Alzheimer's disease, vascular dementia and Parkinson's disease than in the controls. The other system was developed for determination of CA acidic metabolites and 5-HIAA in human urine. This system consisted of a mixed-mode column (C18/anion) and 8-channel electrochemical detector with isocratic elution of citrate buffer. Detection limits, precision and analytical recoveries of this method were satisfactory for clinical use.

On the mechanism of inactivation of active papain by ascorbic acid in the presence of cupric ions

An inactivation mechanism of active papain (EC 3.4.22.2) by the Cu(2+)-ascorbic acid (AsA) system was examined. Incubation of active papain, which contains an active sulfhydryl (SH) group, with the Cu(2+)-AsA system under aerobic conditions resulted in an irreversible loss of enzyme activity. The enzyme was not inactivated at a molar ratio of enzyme to Cu2+ of 1:< 1, whereas at a molar ratio of 1:1-2, the extent of inactivation showed the same dependence on the extent of oxidation of AsA. Saturation kinetics were observed with respect to the concentration of AsA. The degree of inactivation was dependent on the decrease in SH content of the enzyme. Catalase at a low concentration partially protected the enzyme from inactivation, but did not affect the oxidation of AsA. In addition, catalase at a high concentration completely protected both the enzyme from inactivation and AsA from oxidation. The present results suggest that an additional function of H2O2, besides producing hydroxyl radicals (.OH), is to promote the conversion of Cu+ into Cu2+, and that an active SH group of papain is site-specifically modified by the .OH, resulting in inactivation of the enzyme.

Intergenic suppression in a beta subunit mutant with defective assembly in Escherichia coli F1ATPase. Second-site mutation in the alpha subunit

Substitution of Leu-40 by Pro in the beta subunit (beta L40P) of Escherichia coli F1-ATPase caused a decrease in the amount of the alpha and beta subunits on the membranes. A revertant strain, Re50, carrying no suppression mutations in the uncD gene encoding the beta subunit, was isolated from the beta L40P mutant. The uncA gene from this revertant was amplified by PCR, and cloned into an expression plasmid. The expression plasmid carrying the uncA gene from the revertant was used for genetic suppression assays. The suppression mutation in Re50 was in the alpha subunit, and it recovered the assembly of the alpha and beta subunits into the F1F0 complex and the ATPase activity to 50% that of the wild type. In Re50, Leu-111 was substituted by Gln in the alpha subunit. These results suggest that the regions including Leu-40 in the beta subunit and Leu-111 in the alpha subunit are located close together and interact with each other, either directly or indirectly.

[A case of angiocentric immunoproliferative lesions in an ATL-virus carrier]

A 48-year-old woman was admitted to our hospital because of cough and low-grade fever. Chest X-ray films showed multiple ill-defined nodular shadows and laboratory findings showed that she was an ATL-virus carrier. Because the specimens obtained by transbronchial biopsy were not diagnostic, open thoracotomy was performed. Open lung specimens showed proliferation of lymphoid cells composed of polymorphorous lymphocytes, which do not represent cytologic atypia, plasma cells and histiocytes without necrosis. Several vessels were occluded by the infiltration of these cells. A diagnosis of angiocentric immunoproliferative lesions (Grade I), which was originally coined by Jaffe, was made. Complete remission was achieved by treatment with prednisolone and cyclophosphamide. This disease, which corresponds to lymphomatoid granulomatosis, is graded into three categories depending on the severity of cytologic and histologic malignancy. Although it has recently been suggested that its pathogenesis may be related to EB-virus infection, ATL-virus may have been a contributory factor in this case.

Effect of radical scavengers on the inactivation of papain by ascorbic acid in the presence of cupric ions

Incubation of papain (EC 3.4.22.2) with ascorbic acid (AsA) and Cu2+ in acetate buffer (pH 5.6) results in an irreversible loss of enzyme activity by site-specific generation of free radicals [H. Kanazawa, S. Fujimoto, A. Ohara, Biol. Pharm.Bull., 16, 11 (1993)]. In this study, the effect of some compounds, known free radical scavengers, on the relationship between the inactivation of papain by the Cu(2+)-AsA system and the oxidation of AsA was investigated. Catalase completely protected the enzyme from inactivation by the Cu(2+)-AsA system, although hydrogen peroxide (H2O2) by itself, known to be generated during the autoxidation of AsA, did not inactivate the enzyme. The oxidation of AsA was unaffected by catalase. Both thiourea and sodium thiocyanate completely protected the enzyme from inactivation, while AsA was partially oxidized only in the initial stage. In the presence of potassium iodide, both the inactivation of the enzyme and the oxidation of AsA were characterized by a rapid initial phase followed by a stable phase where no reaction took place and, subsequently, a slower phase. Histidine partially prevented the inactivation of the enzyme and the oxidation of AsA. The present results suggest that H2O2 serves as a source of secondary, highly reactive species, probably hydroxyl radicals, which are responsible for the inactivation, and that the protection from inactivation by some radical scavengers, such as thiourea, sodium thiocyanate, potassium iodide, and histidine, is based on the removal of metal ions (Cu2+ or Cu+) at the specific site of inactivation.

[Two case reports of recurrent mediastinitis with chronic mediastinal fistula successfully treated with muscle flap re-transposition]

We experienced two cases of recurrent poststernotomy mediastinitis with chronic mediastinal fistula. Both cases had already received muscle flaps for post operative mediastinitis. However, chronic mediastinal fistula appeared after nine months in the first case, and eleven months in the second case. We removed the infected tissue and the predgets, which were used on the ascending aorta. Then closed the wound by the muscle flap closure. The chronic fistula were closed, and the functional and cosmetic results were excellent.

[An experience of transjugular intrahepatic portosystemic shunt in the treatment of gastroesophageal varices]

Transjugular intrahepatic portosystemic shunt (TIPS) using an 8-mm Gianturco-Rösch Z stent was performed in 10 patients with liver cirrhosis admitted due to ruptured gastroesophageal varices. The treatment was successful in 9 patients, and the portal pressure decreased form 25 mmHg to 17 mmHg immediately after TIPS and to 15 mmHg 2 weeks after TIPS. The patency of the shunt was maintained adequately in the patients examined 3 months after TIPS. Endoscopy 1 month after TIPS showed improvements in the gastroesophageal varices in all patients. Hemobilia and intraperitoneal bleeding were observed in 1 patient each during procedure. Transient jaundice was observed in 2 and increase in the blood ammonia level were noted in 3 (one of whom had hepatic encephalopathy) postoperatively. All these complications could be treated easily. TIPS which brings about an immediate marked reduction in the portal pressure appears to be promising as a new treatment for portal hypertension.

Amino acid replacements at binding sites of monoclonal antibody in the F1-ATPase beta subunit from Escherichia coli caused altered subunit interactions

The monoclonal antibodies (mAb), beta 12 and beta 31, against the beta subunit of Escherichia coli F1-ATPase (Miki, J., Matsuda, T., Kariya, H., Ohmori, H., Tsuchiya, T., Futai, M., and Kanazawa, H. (1992) Arch. Biochem. Biophys. 294, 373-381) recognize the amino-terminal portion of the maximal 104 residues that are not exposed to the surface of the F1-ATPase. To identify the epitope residues within these 104 residues, we introduced random mutations in the region, and clones without binding activity to the mAb, beta 12 and beta 31, were screened. beta subunits defective in binding with mAb beta 12 or beta 31 had amino acid replacements at residues 26, 40, 52, 71, and 74 or at residues 40, 41, 43, 44, 46, and 52, respectively. These residues could be part of the epitope and are possibly located close together. We tested the effects of the mutations on oxidative phosphorylation-dependent growth by introducing expression plasmids of the beta subunit gene with the point mutations into the beta-less mutant, JP17. The alpha and beta subunits were missing from the JP17 membranes, and both subunits were assembled functionally after expression of the beta subunit was induced by introducing the expression plasmid. The replacement of Leu-40 by Pro caused the amounts of the alpha and beta subunits on the membranes to be reduced less than 20% of the amounts in wild type. The replacement of Glu-41 by Lys caused a loss of the alpha subunit on the membranes, without any decrease in the beta subunit. These results indicated that the mutation of Leu-40 to Pro affects the essential role of the beta subunit in the assembly of the alpha and beta subunits on the membranes and that the mutation of Glu-41 to Lys partly affects it. The amino-terminal region of the beta subunit, in particular its ternary structure, including residues 40 and 41, plays an important role in the molecular assembly of the alpha and beta subunits on the membranes.

Fine structure of the canine taste bud with special reference to gustatory cell functions

Canine taste buds were observed by transmission electron microscopy with special reference to the gustatory cell function. The cells forming the taste bud were divided into five types: four of these corresponded to the previously reported Types I, II, III and IV (basal cell); another type, a slender, immature-looking cell located at the outermost layer, was identified as the peripheral cell known in the rat. The Type I cell was supportive in nature, located between other cell types and enveloping nerve fibers. This cell apically secretes dense mucous substances. The Type II cell was in broad contact with nerve fibers and constantly contained a subsurface cistern beneath them. In the dog, this cell was characterized by a large supranuclear Golgi apparatus. The Type III cell was, as in other animals, regarded as the gustatory cell since it made synaptic contacts with nerves and contained synaptic vesicles. Numerous large corded vesicles were intermingled with some small clear vesicles. In addition to accumulating to the synaptic areas, the vesicles often filled the base of the cell, which was irregularly thickened, showing a more or less extensive contact with the basement membrane. In this area, numerous large cored vesicles approached the cell base. Blood capillaries close to the base of the taste bud were fenestrated in the endothelium. These findings supported a hypothesis that the transmitters may be released from the base of the gustatory cell and possibly exert paracrine and endocrine (hemocrine) effects. The salivary gland of Ebner was suggested as one such target. The nerve terminals on the Type III cell also contained synaptic vesicles, suggesting a reciprocal nature of the synapses. The Type IV cell was the immature basal cell which has been established in other species; mitosis could be seen in this cell.

Met-enkephalin-Arg6-Gly7-Leu8-like immunoreactivity in mammalian taste buds

Light-microscopic immunocytochemistry for various bioactive peptides including some gastroenteropancreatic hormones and a neuronal enzyme, neuron-specific enolase (NSE), was applied to taste buds in the circumvallate papillae of rats, mice and guinea pigs. In all the species positive immunoreactivities were demonstrated for Met-enkephalin-Arg6-Gly7-Leu8 (Met-Enk-8). The Met-Enk-8-like immunoreactivity was confined to parts of the spindle-shaped bud cells. These cells in rats and guinea pigs displayed a concomitant immunoreactivity for NSE. In the mouse taste buds, however, there appeared no such correlation between the immunoreactivities. Considering our previous data, the present finding supports a possibility that opioid peptide(s) derived from preproenkephalin A might be the transmitter(s) of the gustatory cell.

Exocrinopathy resembling Sjögren's syndrome induced by a murine retrovirus

BACKGROUND

Sjögren's syndrome (SS) is characterized by lymphocytic infiltration into, and destruction of exocrine glands, resulting in dryness of the mouth and eyes. The disease is considered to have an autoimmune etiology, however, its etiopathogenesis remains largely unknown. Recently, retrovirus is suggested to participate in the pathogenesis of SS, because SS-like lesions are reported in HIV infection or in human T cell leukemia virus type I infection. Moreover, human intracisternal A-type retroviral particles are reported to be detected in SS patients. During the course of our study on the histopathology of mice infected with a murine retrovirus, we happened to find SS-like exocrinopathy in those mice.

EXPERIMENTAL DESIGN

Four-week-old C57BL/6 (B6) mice were injected intraperitoneally with LP-BM5 murine leukemia virus. This virus is known to induce splenomegaly, lymphadenopathy followed by lymphoid malignancy, and profound immunodeficiency in sensitive strains of mice. From 4 to 16 weeks after the virus inoculation, the infected mice were sacrificed and their submandibular and lacrimal glands were analyzed light and electron microscopically and immunohistochemically. The existence of the virus in the lesion in situ was also analyzed by the same method, and additionally by a polymerase chain reaction method.

RESULTS

Periductal lymphocytic infiltration into the submandibular and lacrimal glands was observed in all the virus-infected mice at 4 weeks after the infection and progressed with time. Extraglandular lymphocytic infiltration was also observed in liver, kidney, lung, and pancreas. Immunohistochemical examination revealed that most infiltrating cells into the glands were composed of CD3+ T cells (CD4-dominant), Mac-1+ cells, and B220+ cells. The virus genome was detected in submandibular glands by immunohistochemistry or by polymerase chain reaction. In addition, retroviral particles were secreted into the lumen of exocrine ducts of submandibular glands.

CONCLUSIONS

This might be an SS animal model that is induced by a certain defined retrovirus. This experimental system might provide us with valuable information for analyzing the mechanisms of how a retrovirus could induce SS.

Comparison of portal pressure with intravascular esophageal variceal pressure (IEVP) directly measured with a flexible indwelling needle

Intravascular esophageal variceal pressure (IEVP) was measured using a flexible indwelling needle and compared with wedged hepatic venous pressure (WHVP) in 38 patients with liver cirrhosis. There was a high correlation between IEVP and WHVP; the former was lower than the latter, indicating the presence of a pressure gradient. Bleeders with a history of esophageal variceal rupture showed higher IEVP value than non-bleeders without a history of rupture, even though no difference in WHVP was observed. IEVP in the post-endoscopic injection sclerotherapy (EIS) group, even in those with endoscopic findings of large varices, was lower than that in the untreated groups. These results suggest that IEVP is a factor in the hemodynamics of patients with portal hypertension and that its measurement may be helpful in elucidating the pathophysiology of esophageal varices.

[Propranolol for prophylaxis of first hemorrhage in cirrhotic patients with esophageal varices--a controlled study comparing with sclerotherapy]

To compare the efficacy of oral propranolol and sclerotherapy in the prevention of first hemorrhage from esophageal varices, 65 cirrhotic patients with moderate to large esophageal varices and no history of bleeding were included in the prospective controlled trial. After randomization, 33 patients received propranolol at a does reducing the heart rate by 25%; 32 patients were treated with intra-variceal and extra-variceal injection of ethanolamine oleate. On entry to the trial, the two groups were comparable in terms of clinical and biological parameters. The patients were observed for up to 60 months, with an average of 31 months. Nine patients bled (5 in propranolol and 4 in sclerotherapy) during follow-up. No significant difference were observed between propranolol and sclerotherapy in the cumulative bleeding rate and survival. The multivariate Cox model indicated that drug compliance in the propranolol group and high portal pressure in the sclerotherapy group were factors predictive of the first hemorrhage. These data support that propranolol and sclerotherapy are of comparable value in preventing the first hemorrhage in cirrhotic patients with esophageal varices.

Mesenchymal chondrosarcoma of the jaw--report of a case and review of 41 cases in the literature

A case of mesenchymal chondrosarcoma in the mandible of a 35-year-old woman is presented. In a thorough survey of the world literature, 41 cases of mesenchymal chondrosarcoma occurring the jaw are reviewed.

Arginine vasopressin increases perinuclear [Ca2+] in single cultured vascular smooth muscle cells of rat aorta

The effects of arginine vasopressin (AVP, 10(-7) M) on the spatial dynamics of intracellular [Ca2+] in single cultured smooth muscle cells of the rat aorta were studied by digital imaging microscopy using the fluorescent Ca2+ indicator fura-2. The nuclear and cytosolic regions were distinguished by the fluorescent image excited at 380 nm. Changes in intracellular [Ca2+] were expressed as percent increases in the ratios of fluorescence intensity at 500 nm excited by 340 and 380 nm. AVP increased the nuclear and cytosolic [Ca2+] in Ca(2+)-containing (control) (285 +/- 27 and 172 +/- 22%, respectively) or Ca(2+)-free (203 +/- 26 and 121 +/- 15%, respectively) solutions. However, caffeine (20 mM) and ryanodine (20 microM) greatly attenuated the [Ca2+] increase induced by AVP in both regions (61 +/- 21 and 42 +/- 15%, respectively). On the ratio image, the nuclear region was discriminated from other regions at the peak response to AVP in preparations treated with caffeine and ryanodine, whereas the outline of the nuclear region was indistinct in untreated preparations. The finding implies that caffeine- and ryanodine-responsive Ca2+ storage sites may exist in the region surrounding the nucleus. The results suggest that the region surrounding the nucleus may be one of the important Ca2+ storage sites with regard to the responses of rat aortic smooth muscle cells to AVP.

Solitary plasmacytoma of the mandible. Case report and review of the literature

A case of solitary plasmacytoma of the mandible is presented. Review of the literature disclosed the following characteristics regarding the clinical course and prognosis. The patients ages ranged from 34 to 76 years, with a mean of 53 years; there was a marked preponderance of males. The site of predilection was the posterior portion of the mandible. The common symptom was a non-painful swelling of the mandible of long duration, and radiological features were non-specific. Monoclonal immunoglobulin was initially detected in 42% of the evaluated patients. The majority of patients were treated with radiation therapy with a mean dose of 48Gy with or without surgery. The period of follow-up ranged from 4 months to 12 years, and 17% of the patients progressed to multiple myeloma within 1 year.

Effect of neuropeptide Y on human bronchus and its modulation of neutral endopeptidase

BACKGROUND

Neuropeptide Y (NPY) and neutral endopeptidase have been shown to regulate the response of airway smooth muscle. However, their interactions have not been studied.

METHODS

To determine the role of NPY and endogenous neutral endopeptidase in regulating the effects of NPY, we investigated the effects of NPY and a neutral endopeptidase inhibitor, phosphoramidon, on the contractile response of isolated human bronchial segments to electrical field stimulation (EFS).

RESULTS

Concentrations of up to 10(-6) mol/L of NPY did not change resting tension. NPY inhibited the cholinergic contractions induced by EFS at 5 Hz dose-dependently. Phosphoramidon (10(-5) mol/L) enhanced the inhibitory effect of NPY on EFS-induced contractions at 5 Hz. NPY (3 x 10(-7) mol/L) shifted the frequency-response curve for EFS (1 to 50 Hz) to the right and significantly increased the mean logarithm of frequency that produced 50% of maximal contraction (control: 0.54 +/- 0.07 versus NPY: 0.79 +/- 0.09, p < 0.05). Phosphoramidon (10(-5) mol/L) did not affect the frequency response to EFS, but enhanced the inhibitory effect of NPY (3 x 10(-7) mol/L) on frequency response to EFS, resulting in a significant increase in the mean logarithm of frequency that produced 50% of maximal contraction (NPY: 0.79 +/- 0.09 versus NPY plus phosphoramidon: 1.18 +/- 0.15, p < 0.05). NPY (3 x 10(-7) mol/L) did not affect the response of tissues to exogenously applied acetylcholine.

CONCLUSIONS

These observations suggest that NPY inhibits the output of acetylcholine from nerve endings and that endogenous neutral endopeptidase modulates the effect of NPY in the human airway by inactivating this peptide.