Coupled oscillator systems of cultured cardiac myocytes: fluctuation and scaling properties

Isolated and cultured neonatal cardiac myocytes exhibit autonomous rhythmic contraction, and their dynamics vary dramatically depending on the extent of mutual coupling among individual myocytes. We study the temporal changes of interbeat interval series in aggregated systems of spontaneously beating cultured neonatal rat cardiac myocytes and observe a rich variety of complex, nonlinear features such as frequent alternations, bistability, and periodic spikes. Fluctuation analysis of the interval series reveals that there occurs a transition in scaling behavior from persistent correlations to antipersistent correlations as the coupling develops with incubation time. Additionally, we perform computer simulations using interacting Bonhoeffer-van der Pol oscillators to understand the effects of coupling on the fluctuation dynamics of each constituent oscillator. We find that the formation of strong and heterogeneous coupling among the oscillators is a key factor to yield the complexity in the interval series as well as in the scaling behavior.

Improvement of adult Still's disease with granulocyte and monocyte adsorption apheresis

Adult Still's disease is characterized by a high spiking fever, transient skin rash, and polyarthralgia. Joint pain is one of the major complaints and is often intractable. We assessed the efficacy of granulocyte and monocyte adsorption apheresis (GCAP) therapy for treating arthralgia in adult Still's disease. A 33-year-old woman with adult Still's disease who suffered from recalcitrant arthralgia resistant to systemic corticosteroids was treated with GCAP therapy. She underwent five GCAP treatments at 5-day intervals. Her joint pain responded dramatically to the GCAP therapy, suggesting that GCAP may be useful for treating adult Still's disease. We present a detailed description of the patient and this novel therapy.

Nitric oxide produced during ischemia is toxic but crucial to preconditioning-induced ischemic tolerance of neurons in culture

The present study investigated the roles of nitric oxide (NO) in preconditioning (PC)-induced neuronal ischemic tolerance in cortical cultures. Ischemia in vitro was simulated by subjecting cultures to both oxygen and glucose deprivation (OGD). A sublethal OGD (PC) significantly increased the survival rate of neurons when cultures were exposed to a lethal OGD 24 h later. Both the inhibition of nitric oxide synthase (NOS) and scavenging of NO during PC significantly attenuated the PC-induced neuronal tolerance. In addition, exposure to an NO donor emulated the PC. In contrast, the inhibition of NOS and the scavenging of NO during lethal OGD tended to increase the survival rate of neurons. This study suggested that NO produced during ischemia was fundamentally toxic, but critical to the development of PC-induced neuronal tolerance.

Mediastinal Solitary Fibrous Tumor: Report of a Case with Direct Invasion to the Trachea

The solitary fibrous tumors in the pleura are a rare entity that is usually adhesive and sometimes invasive. Because of its benign feature, complete surgical resection is generally considered. We describe a very rare case of mediastinal solitary fibrous tumor arised or invaded into the tracheal wall, which was surgically resected with combined cylindrical resection of the trachea.

Spectral and correlation analyses of the verapamil-induced conversion of ventricular fibrillation to tachycardia in isolated rat hearts

Ventricular tachycardia (VT) is considered to be the most common precursor of ventricular fibrillation (VF). However, the mechanisms underlying the transition from VT to VF remain unclear. Here, we investigated whether and how perfusion of the heart with verapamil, a blocker of L-type calcium channels, changed the macro-dynamics of the heart between VT and VF. The experiments were performed with Langendorff perfused isolated rat hearts, in which left ventricular pressure and left ventricular cardiomyogram were measured. Sustained VT or VF was induced by burst pacing of the left ventricular muscles. During sustained VF, verapamil perfusion resulted in the conversion of VF to VT. A cross-correlation analysis between left ventricular cardiomyogram and left ventricular pressure revealed that the correlation coefficient was small during VF, but became larger during VT. This study showed that inactivation of L-type Ca(2+) channels occurred during verapamil-induced conversion of pacing-induced sustained VF to VT, and characterized the changes in macro-dynamics of the heart associated with the transition.

Microneurography in anesthetized rats for the measurement of sympathetic nerve activity in the sciatic nerve

Microneurography is widely used for the measurement of human peripheral sympathetic nerve activity (SNA) in conscious subjects by virtue of its low invasive nature, but has rarely been employed in animal experiments. Because the low invasive nature sometimes is very useful even in animal experiments, we tested its feasibility for the measurement of SNA in the sciatic nerve of the anesthetized rat, aiming in particular to establish a methodology for measurement. A tungsten microelectrode was inserted into the nerve exposed at the thigh level to detect the "spontaneous, intermittent burst" signal that is one of the main characteristics of compound SNA. Such signals were found in more than 70% of experiments after surgical operators became accustomed to the method. Whenever such signals were detected, electrical stimulation of the sympathetic chain resulted in induced action potentials detected with the microelectrode after a reasonable conduction period. The spikes were successfully reduced after administration of hexamethonium bromide, a sympathetic ganglion blocker. On the other hand, induced spikes were never observed when we failed to find the "spontaneous, intermittent burst" signal. The results demonstrate the feasibility of microneurography in evaluating SNA in anesthetized small animals, and that the "spontaneous, intermittent burst" signal may be sufficient to identify SNA.

Ruthenium red-induced transition from ventricular fibrillation to tachycardia in isolated rat hearts:

INTRODUCTION

Ventricular tachycardia (VT) is considered to be the most common precursor of ventricular fibrillation (VF) and sudden cardiac death. However, the mechanisms underlying the transition from VT to VF remain unclear despite more than a century of study. Here, we investigated whether perfusion of the heart with blockers of mitochondrial Ca(2+) uniporter changed the macrodynamics of the heart between VT and VF.

METHODS

The experiments were performed using Langendorff perfused isolated rat hearts in which left ventricular pressure (LVP) and left ventricular cardiomyogram (LVCMG) were measured. Sustained VT or VF was induced by burst pacing of the left ventricular muscles.

RESULTS

During pacing-induced sustained VF, perfusion of the heart with ruthenium red (RR) or Ru 360, blockers of mitochondrial Ca(2+) uniporter, resulted in the reversible conversion of VF to VT. In contrast, during pacing-induced sustained VT, perfusion of the heart with spermine, an activator of mitochondrial Ca(2+) uptake, resulted in the reversible conversion of VT to VF, and the effect was antagonized by cotreatment with RR. In addition, RR-induced conversion of VF to VT was antagonized by cotreatment with S(-)-Bay K8644 (Bay K), an activator of L-type Ca(2+) channels, suggesting that the inactivation of L-type Ca(2+) channels was responsible for the RR-induced effect on the macrodynamics of hearts. In fact, perfusion with verapamil, an antagonist of L-type Ca(2+) channels, during pacing-induced sustained VF, resulted in the conversion of VF to VT.

CONCLUSION

This study demonstrated that perfusion of isolated rat hearts with blockers of Ca(2+) uptake by mitochondria resulted in the reversible conversion of pacing-induced sustained VF to VT, suggesting that changes in mitochondrial Ca(2+) uptake were possibly involved in the transition between VT and VF.

Evaluation of lung volume reduction surgery (LVRS) based on long-term survival rate analysis

OBJECTIVE

Lung volume reduction surgery (LVRS) is an effective therapy for some patients with end-stage emphysema. In most cases, functional improvement is maximized during the first 6 months after surgery and decreases steadily afterwards. This study was aimed at gaining further understanding of the optimal candidates for LVRS and survival rates.

METHODS

62 patients with LVRS were selected according to the inclusion criteria. Changes in lung function were evaluated by FEV1, VC, RV, TLC, DLCO, PaO2, and PaCO2, and survival rates were analyzed at 12, 24, 36, and 48 months. Patients with LVRS were divided into two groups--those surviving after 48 months and those not surviving after 48 months--and analyzed according to group.

RESULTS

The overall survival rate at 2 years and 4 years was 81.0 % and 67 %, respectively, with LVRS. VC, FEV1, TLC, DLCO, PaO2, and PaCO2 were potential factors leading to mortality according to univariate analysis. Multivariate analysis demonstrated that DLCO was the only independent factor that could predict the post-LVRS prognosis; the other factors failed as independent factors. Preoperatively, the FEV1 percentage predicted gave a good index for post-LVRS survival.

CONCLUSIONS

Patients with higher preoperative FEV1 values had higher survival rates. These favorable long-term survival rates might justify LVRS for treating selected patients with severe emphysema. Additionally, DLCO turned out to be the only predictive factor for high mortality risk 4 years after LVRS. DLCO may thus be a very important marker in surgical planning.

The agonist of the protease-activated receptor-1 (PAR) but not PAR3 mimics thrombin-induced vascular endothelial growth factor release in human smooth muscle cells

Thrombin, a serine protease generated by the activation of the blood coagulation cascade following vessel injury, induces vascular endothelial growth factor-(VEGF) release. However, the molecular mechanism of thrombin-induced VEGF release is largely unknown. Anagonist of protease-activated receptor-i (PARI), SFLL-RNPNDKYEPF, mimicked thrombin-induced VEGF release in human vascular smooth muscle (HVSM) cells, as determined by enzyme-linked immunosorbent assay, reverse transcriptase-polymerase chain reaction, and Northern blotting. In contrast, the agonist of PAR3, TFR- GAP, did not affect VEGF release or expression. SFLL-RNPNDKYEPF, but not TFRGAP, up-regulated [Ca2-]i.Moreover, the calcium ionophone A23187 was found to trigger VEGF release in HVSM cells. Thrombin-inducedVEGF release was blocked by anti-thrombin, heparin, a synthetic thrombin receptor inhibitor E5510, the calcium chelator BAPTA, the protein kinase C inhibitor calphostin C, and the MEK1/2 inhibitor U0126. Thus, our data show that thrombin caused VEGF release via PARI activation in a manner dependent on [Ca2+]i and p44/42 downstream from the receptor activation.

Anandamide induces apoptosis in human endothelial cells: its regulation system and clinical implications

Anandamide (AEA), an endogenous cannabinoid, is generated by macrophages during shock conditions, and is thought to be a causative mediator of septic shock. Thus, we hypothesized that AEA plays a crucial role in endothelial cell (EC) injury. Here, we demonstrate that AEA induces apoptosis in a time-and dose-dependent manner in human umbilical vein endothelial cells (HUVECs). AEA triggered phosphorylation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen activated protein kinase. AEA also showed a marked increase of interleukin Ibeta- converting enzyme (ICE)CED-3 family protease (caspase-3) activity. AEA-induced EC death was inhibited by a selective vanilloid receptor 1 (VR1) antagonist, capsazepine, and was enhanced by a VR1 agonist, capsaicin, indicating that AEA induces apoptosis in ECs via VR1. In conclusion, we propose that AEA may play a crucial role in EC injury under conditions of shock, and that the use of inhibitors of the AEA regulation system may have a therapeutic effect under these conditions.

Video-assisted thoracic needle aspiration cytology for malignancy of the peripheral lung

BACKGROUND

The technique of video-assisted thoracic fine-needle aspiration cytology (VAT-FNA) to the lung has been described in very few publications, and its diagnostic role has not been evaluated so far. Thus current studies focus on whether the diagnostic role could be applied usefully to VAT-FNA of peripheral lung lesions.

METHODS

Between January 1995 and January 2000, a total of one hundred and twenty-eight cases of VAT-FNA on lung tumors were reviewed retrospectively. The superficial lung was visualized a part of directly or indirectly by scope and a 22-gauge needle inserted for FNA. Material was expressed onto glass slides, and smears were stained by our modified quick-stain method. The cytological diagnoses based on VAT-FNA were reviewed and compared with the final histopathological diagnoses.

RESULTS

The cytological diagnosis was true positive in 100 cases (93.5% sensitivity), whereas the true negative result in 20 cases was 95.2% specificity. The false-positive rate was 4.8%, and false-negative results were 6.5%. The accordance in all malignant cases between cytology and histology was 73.8%. VAT-FNA caused no difficulties in any of the cases.

CONCLUSION

The application of VAT-FNA to the peripheral lung lesion is not only useful, cost-beneficial, safe and minimally invasive but also accurate. Especially, this method may play an important role in cases of suspected malignancy in peripheral cases.

[Surgical treatment for esophageal cancer in elderly patients over 75 years of age]

We performed 127 esophageal resections for the esophageal cancer patient from December 1995 to September 2001. It was separated to under 70 years old patients group (group I), 71-74 years old patients group (group II), and over 75 years old patients group (group III).

RESULTS

Postoperative complication was occurred in 53 cases (41.7%) within all of 127 esophageal resected cases. It was 33.7% in group I, 53.6% in group II, 62.5% in group III. Four years survival rate of each group is 38.3% in group I, 44.6% in group II, 31.3% in group III. It is significantly better in group II rather than in group III. Operative death rate is 12.5% (2 cases) in group III, 7.1% (2 cases) in group II, 3.6% (3 cases) in group I, and it is gradually higher and higher by patient's age.

CONCLUSIONS

(1) In the esophageal cancer patient over 75 years old, postoperative complication rate is higher than under 74 years old patients, and prognosis is significantly poor rather than in 70-74 years old patients group. (2) In the esophageal cancer patient over 75 years old, we considered it is good indication of esophagectomy for stage I and stage II patient without preoperative complication, however, there are no operative indication for stage III and stage IV patient.

Increased vulnerability to ischemia/reperfusion-induced ventricular tachyarrhythmias by pre-ischemic inhibition of nitric oxide synthase in isolated rat hearts

INTRODUCTION

The relationship between vulnerability to reperfusion-induced ventricular tachyarrhythmias, such as ventricular tachycardia (VT) and fibrillation (VF), and the endogenous activity of nitric oxide synthase (NOS) has not been well documented. The objective of the present study was to clarify whether the vulnerability to reperfusion-induced VT/VF changes with preishemic, sustained inhibition of NOS.

METHODS

The experiments were performed using Langendorff-perfused isolated rat hearts, in which left ventricular pressure (LVP) and left ventricular cardiomyograms (LVCMGs) were measured.

RESULTS

A pre-ischemic, sustained inhibition of NOS resulted in an increased vulnerability to reperfusion-induced VT/VF, and the increase was markedly attenuated by co-treatment with L-arginine or by post-ischemic treatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of tetrahydrobiopterin (BH(4)) synthesis. We then tried to elucidate whether nitric oxide (NO) and superoxide were produced during reperfusion, and ATP-sensitive potassium channels (K(ATP)), especially mitochondrial ATP-sensitive potassium channels (mitoK(ATP)), are involved in the increased vulnerability. Post-ischemic inhibition of NOS and treatment with a NO scavenger attenuated the increased vulnerability to reperfusion-induced VT/VF, but post-ischemic treatment with a superoxide scavenger did not. In addition, post-ischemic treatment with S-nitroso-N-acetyl-DL-penicillamine (SNAP), a NO donor, or with diazoxide, a selective opener of mitoK(ATP), increased the VT/VF duration during reperfusion. The increased vulnerability to VT/VF was attenuated by the treatment with a selective mitoK(ATP) blocker.

CONCLUSION

The results suggest that a pre-ischemic, sustained inhibition of NOS increases the vulnerability to reperfusion-induced VT/VF, and the NO-mitoK(ATP) pathway is one of the possible factors contributing to the increased vulnerability to VT/VF.

Possible Involvement of Apoptotic Death of Myocytes in Left Ventricular Remodeling after Myocardial Infarction

Pathophysiological roles of apoptosis in post-infarction left ventricular (LV) remodeling have not been well characterized. This study showed that TUNEL- or cleaved caspase-3-positive myocytes were identified late after ligation of the left coronary artery in rats, suggesting that apoptotic myocyte death contributed to the morphological change associated with LV remodeling.

Selective blockade of astrocytic glutamate transporter GLT-1 with dihydrokainate prevents neuronal death during ouabain treatment of astrocyte/neuron cocultures

Glutamate (Glu) is a major excitatory neurotransmitter of the mammalian central nervous system and under normal conditions plays an important role in information processing in the brain. Therefore, extracellular Glu is subject to strong homeostasis. Astrocytes in the brain have been considered to be mainly responsible for the clearance of extracellular Glu. In this study, using mixed neuron/astrocyte cultures, we investigated whether astrocytic Glu transporter GLT-1 is crucial to the survival of neurons under various conditions. Treatment of the mixed cultures with a low concentration of Glu did not produce significant death of neurons. However, cotreatment with dihydrokainate (DHK), a specific blocker of GLT-1, resulted in significant neuronal death that was suppressed by an antagonist of N-methyl-D-aspartate (NMDA) receptors. These results suggested that astrocytic GLT-1 participated in the clearance of extracellular Glu and protected neurons from NMDA receptor-mediated toxicity. When the cultures were treated with ouabain, an inhibitor of Na(+)/K(+)-ATPase, a low concentration of Glu resulted in massive neuronal death that was also suppressed by cotreatment with an antagonist of NMDA receptors. In this case, however, cotreatment with DHK significantly protected neurons from death, suggesting that GLT-1 was responsible for the death of neurons. The present study provides evidence suggesting that astrocytes use their Glu transporter GLT-1 to protect neurons from Glu toxicity, but, ironically, also use GLT-1 to kill neurons through Glu toxicity depending on their status.

Smoking behavior, initiating and cessation factors among Japanese nurses: a cohort study

The prevalence of smoking among Japanese nurses, specially in their twenties, is higher than that among the general female population. To examine smoking behavior, smoking initiating and cessation factors, we conducted a cohort study through questionnaire survey, targeting nurses (n=1572) working at 11 hospitals located in Tokyo metropolitan area. The first survey was conducted using a confidential questionnaire on smoking, followed by a second survey conducted in the same manner on the same subjects two years later. As to smoking status after two years, 8% (95%CI=1.5%) started smoking and 6% (95%CI=1.4%) quitted resulting in a 2% increase in the prevalence of current smoking. The average nicotine dependence for nurses who were smokers in the two surveys rose from 3.9 to 4.3 (P<0.05). Smoking behavior of mother, friends, or superiors at work had a significant influence on smoking behavior of nurses. As to smoking cessation factors, the idea that women and medical workers should not smoke, and living with family each had a significant influence. Considering the fact that 6% of nurses in this study succeeded in quitting smoking within two years, it is required that anti-smoking education be conducted at medical institutions to decrease the prevalence of current smoking among the nurses in Japan.

Relationship between the activation of cyclic AMP responsive element binding protein and ischemic tolerance in the penumbra region of rat cerebral cortex

Application of a brief period of ischemia, i.e. preconditioning treatment of the middle cerebral artery territory, has been known to produce ischemic tolerance, reducing cerebral infarction volume in the penumbra region after lethal ischemia. However, little is known about the molecular mechanisms responsible for preconditioning-induced ischemic tolerance. In the present study, we examined the difference in the phosphorylation pattern of cyclic AMP responsive element binding protein (CREB) after 1 h of focal cerebral ischemia between preconditioned and non-preconditioned rats by immunohistochemistry and Western blotting. The phosphorylation of CREB in the penumbra region was more rapidly enhanced in the preconditioned rats than in the non-preconditioned rats after 1 h of ischemia. The result suggested that the immediate enhancement in the phosphorylation of CREB in the penumbra region prevented the spread of infarction in the preconditioned rats.

[Surgical therapy for patients with thymoma or thymic carcinoma; based on WHO classification]

The treatment strategy for patients with thymoma or thymic carcinoma still has not been confirmed, and the molecular biologic characteristics of these tumors have not been defined also. We have emphasized the clinical significance of this classification so far by the research cooperation with professor Müller-Hermelink, the institute of pathology, Würzburg University. This time, We introduced clinico-pathological findings based on the new WHO classification in 59 Case of thymic epithelial tumor and reffered the treatment strategy for patients with thymic cancer.

Photolytic flash-induced intercellular calcium waves using caged calcium ionophore in cultured astrocytes from newborn rats

Waves of elevated intracellular free calcium that propagate between neighboring astrocytes are important for the intercellular communication between astrocytes as well as between neurons and astrocytes. However, the mechanisms responsible for the initiation and propagation of astrocytic calcium waves remain unclear. In this study, intercellular calcium waves were evoked by focal photolysis of a caged calcium ionophore (DMNPE-caged Br A23187) in cultured astrocytes from newborn rats. The focal photolysis of the caged compound resulted in the increase in intracellular calcium in a single astrocyte, and this increase then propagated to neighboring astrocytes. We also analyzed the spatiotemporal characteristics of the intercellular calcium waves, and estimated the propagation pathways for them. The method using a caged calcium ionophore described in this study provides a new in vitro model for the analysis of intercellular calcium waves.

Increased resistance to nitric oxide cytotoxicity associated with differentiation of neuroblastoma-glioma hybrid (NG108-15) cells

Nitric oxide (NO), synthesized by the enzyme nitric oxide synthase (NOS), acts as an intercellular messenger associated with various physiological and pathological events. In this study, we investigated whether there exits a difference in the vulnerability to NO-induced cytotoxicity between undifferentiated and differentiated NG108-15 cells, and if so, the mechanisms responsible for the difference. Following a 7- to 8-day exposure to dibutyryl cAMP (dbcAMP), NG108-15 cells exhibited a neuron-like morphology associated with the expression of the neuronal protein, synaptophysin, and with increased NADPH-d activity. Neuron-like differentiated NG108-15 cells acquired resistance to exogenously applied NO. This increased resistance to NO toxicity in differentiated cells was almost completely cancelled out by inhibiting the activity of superoxide dismutase (SOD), but not by inhibiting the activity of NOS. The present study suggested that the activity of SOD increased in parallel with the activity of NOS associated with differentiation and was crucial for the acquired resistance to NO toxicity in differentiated cells.

Effect of dietary control on plasma nitrate level and estimation of basal systemic nitric oxide production rate in humans

It is of great interest and value to evaluate the systemic nitric oxide (NO) production rate in humans under various conditions. However, the currently available estimation methods are troublesome and time-consuming. We thus aimed at developing a simple method to estimate the basal systemic NO production rate in humans based on a steady-state analysis, i.e., a balance between the systemic NO production rate and the total nitrate elimination rate. Plasma nitrate concentrations of young healthy volunteers (n = 7 in group 1: n = 9 in group 2) were measured for 2 days. In group 1, all subjects had the same meals for 7 days prior to the plasma nitrate measurement. In group 2, all subjects were allowed free diets. The plasma nitrate concentrations were highly influenced by dietary nitrite/nitrate intake in both groups and reached the steady-state levels after 14-h fasting. Accordingly, the basal systemic NO production rates were estimated from the plasma nitrate concentrations after 14-h fasting (group 1, 630 +/- 37 nmol min(-1) = 0.78 +/- 0.03 micromol kg(-1) h(-1); group 2, 597 +/- 45 nmol min(-1) = 0.66 +/- 0.05 micromol kg(-1) h(-1), P = not significant vs group 1). These estimated values were comparable to the values obtained by other methods. In conclusion, the present estimation method with 14-h fasting using a single-compartment analysis was found to be a simple approach to quantitative evaluation and intra- and interindividual comparisons of the basal systemic NO production rates in humans.

[Clinical study of double primary cancer involving the lung in resected cases]

Among all cases of surgically resected lung cancer, there were 56 cases (16.1%) of double primary cancer. The common sites of the other primary cancer was the stomach (19 cases), followed by large intestine (9 cases), urinary bladder (7 cases) and pharinx-larynx (7 cases). One patient had triple cancers. In all cases of double primary cancer, 46 cases were metachronous, 10 of which were cases of initial lung cancer. The 5-year survival rate of double primary cancer was 39.7%. Good result was obtained in metachronous cases with initial lung cancer. Most of prognosis of double primary cancer was determined by that of lung cancer. In more than half of initial cancer, the second primary cancer was detected by symptoms. So, special attention to the possibility of double primary cancer in patients with resected lung cancer is necessary for improvement of prognosis.

Serosal application of Ba(2+) induces oscillatory chloride secretion via activation of submucosal cholinergic neurones in guinea-pig distal colon

The enteric nervous system regulates ion and fluid secretion in the mammalian intestine at both resting and stimulated conditions. To determine the type and activation mechanism of neurones involved, mucosa-submucosa sheets isolated from guinea-pig distal colon were studied in vitro in Ussing chambers. Serosal addition of 0.5-1 mM barium (Ba(2+)), a potassium (K(+)) channel inhibitor, caused oscillatory increases in short-circuit current (I(sc)). Mean values of the size and frequency of I(sc) were 369.1 microA cm(-2) and 2.3 min(-1). The oscillatory I(sc) induced by the low concentrations of Ba(2+) was blocked by either higher concentrations of Ba(2+) (2-5 mM) or other K(+) channel inhibitors, such as tetraethylammonium (TEA) (1 mM) and quinine (20 mM). The Ba(2+)-induced oscillatory I(sc) was also inhibited by tetrodotoxin (TTX) and atropine. In a nominally Ca(2+) free solution plus serosal addition of 0.1 mM ethylene glycol-bis (beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), a Ca(2+) chelator, the oscillatory I(sc) slowed and diminished. Further, the Ba(2+)-induced oscillatory I(sc) was partially inhibited by apical addition of 100 microM 5'-nitro-2-(3-phenylpropylamino)benzoic-acid (NPPB), a Cl(-) channel inhibitor, and completely disappeared in a low Cl(-) solution (11 mM) on both sides. On the other hand, application of either cimetidine, a histamine H(2) receptor antagonist, or hexamethonium, a nicotinic antagonist, to the serosal side did not affect the Ba(2+)-induced oscillatory I(sc). In conclusion, the Ba(2+)-induced oscillatory I(sc) is the transepithelial Cl(-) current which is stimulated by activation of cholinergic neurones in submucosal plexus of guinea-pig distal colon.