Biomedical subjects

W H Hsu

Publications and source records attributed to W H Hsu.

At least 55 records · Page 3Linked to original sources

PubMed1998

Ultrasound-guided small-bore Elecath tube insertion for the rapid sclerotherapy of malignant pleural effusion.

BACKGROUND: Traditional pleurodesis for malignant pleural effusion is performed by large-bore chest tube insertion with the instillation of sclerosing agents after the compressed lung re-expansion and pleural fluid drainage of 100-150 ml/day. This study was carried out to evaluate the possibility of rapid sclerotherapy for malignant pleural effusions by insertion of a small-bore Elecath tube (12-French) under ultrasound guidance and intrapleural injection of bleomycin 60 IU. METHODS: Twenty-six patients, with 28 cytopathologically proven malignant pleural effusions (two patients had bilateral pleural effusions) and receiving the insertion of the Elecath tube for drainage, were included in our series. This rapid and short-term sclerosing method was performed and completed by intrapleural injection of bleomycin when the pleural effusion had been clearly drained by the small-bore Elecath tube and the compressed lung had fully re-expanded on follow-up chest radiographs. RESULTS: Twenty patients with 22 pleural effusions underwent the intrapleural injection of bleomycin, with the results of pleurodesis being complete response 41% (9/22), partial response 36% (8/22) and failure 23% (5/22). Interestingly, among the 17 successful procedures of pleurodesis (complete response and partial response), 71% (12) procedures could be completed within 2 days (seven within one day and five within 2 days). The remaining unsuccessful procedures carried out on six patients without the injection of bleomycin were due to a non-re-expanded lung (n = 3) and inadequate drainage (n = 3); of these, four patients also received the large-bore chest tube insertion after the removal of the Elecath tube, but the compressed lung still could not re-expand. The complications of the bleomycin injection were fever [77% (17/22)], vomiting [14% (3/22)] and hiccup [5% (1/22)]. CONCLUSION: The method of rapid sclerotherapy for malignant pleural effusions by small-bore Elecath tube is promising, with a success rate achieving 77%, usually within 2 days.

Bleomycin↗

PubMed1998

DNA hybridization and electrokaryotype study of some Candida species.

Some Candida species which were similar to each other in phenotypic characteristics were studied by chemotaxonomic and molecular taxonomic comparison including the ubiquinone systems, electrophoretic karyotypes, DNA base composition and DNA relatedness. Candida viswanathii and Candida lodderae showed similar electrophoretic karyotypes and DNA base composition and demonstrated 89 to 91% DNA relatedness, confirming their synonymy.

Base Composition↗

PubMed1998

The effect of large-dose prednisolone on patients with obstructive lung disease associated with consuming sauropus androgynus.

BACKGROUND: In 1995, the consumption of the vegetable Sauropus androgynus in order to reduce weight led to an outbreak of patients with obstructive ventilatory impairment. The pathologic findings showed bronchiolitis obliterans with or without organized pneumonia. Steroid therapy was used in an attempt to reverse the pulmonary dysfunction even though the pathogenesis was unknown. METHODS: In this retrospective study, we reviewed the response of seven non-smoking female patients who were consuming Sauropus androgynus to large-dose prednisolone therapy (prednisolone > 0.5 mg/kg/day, > 30 days). Conventional pulmonary function testing (PFT) was used to assess patient lung function. RESULTS: All patients had greatly reduced forced expiratory volume in one second (FEV1) before and after steroid treatment. There was no significant change in the parameters of PFT, such as FEV1, forced vital capacity (FVC), FEV1/FVC, and carbon monoxide diffusion capacity (DLco) after prednisolone therapy. CONCLUSIONS: Large-dose steroid therapy was unable to relieve the obstructive ventilatory impairment present in patients after consuming Sauropus androgynus.

Adult↗

PubMed1998

Ultrasound-guided fine needle aspiration biopsy in the diagnosis of pulmonary cryptococcosis.

The purpose of this study was to assess the safety and reliability of ultrasound-guided fine needle aspiration biopsy (US-guided FNAB) combined with modified Papanicolaou's staining in the diagnosis of pulmonary cryptococcosis. The study included 10 patients (9 men, 1 woman, 28-70 yr). Percutaneous US-guided FNAB was performed through a puncture probe with central channel guidance (n = 8) or in a 'free-hand' manner (2), depending on the size of the lesion and the experience of the operator. Sonography disclosed homogeneously hypoechoic lesions with air bronchograms over the peripheral or central portion in nine patients, and occasional heterogeneous echogenicity with necrotic tissue without air bronchogram in one. Thirteen lesions were found on the chest radiographs of the 10 patients; these could be divided into three patterns: infiltrates (2), nodules or masses (7), and consolidation (4). Using US-guided FNAB and immediate modified Papanicolaou's stain, a diagnosis of pulmonary cryptococcosis was confirmed in nine of the 10 patients. The remaining case was proven by surgical resection. No major complications developed after US-guided FNAB. We conclude that this technique, combined with modified Papanicolaou's staining, provides a safe, rapid, and reliable method for diagnosing pulmonary cryptococcosis.

Adult↗

PubMed1998

Production and properties of a raw-starch-degrading amylase from the thermophilic and alkaliphilic Bacillus sp. TS-23.

The optimum temperature and initial medium pH for amylase production by Bacillus sp. TS-23 were 55 degrees C and 8.5 respectively. Maximum amylase activity was obtained in a medium containing peptone and soluble starch as nitrogen and carbon sources. Activity staining revealed that two amylases with molecular masses of 150 and 42 kDa were produced when maltose, soluble starch or amylose was used as carbon source for growth, whereas only the 150 kDa protein was detected in the medium containing water-insoluble carbon sources. A raw-starch-degrading amylase was purified from culture supernatant of Bacillus sp. TS-23. The molecular mass of the purified amylase was estimated at 42 kDa by electrophoresis. The enzyme had a pI of 4. 2. The optimal pH and temperature for activity were 9.0 and 70 degrees C respectively. The thermoactivity of the purified enzyme was enhanced in the presence of 5 mM Ca2+; under this condition, enzyme activity could be measured at a temperature of 90 degrees C. The enzyme was strongly inhibited by Hg2+, Pb2+, Zn2+, Cu2+ and EDTA, but less affected by Ni2+ and Cd2+. The enzyme preferentially hydrolysed high-molecular-mass substrates with an alpha-1, 4-glucosidic bond except glycogen. The raw starches were partly degraded by the purified amylase to yield predominantly oligosaccharides with degrees of polymerization 3, 4 and 5.

Bacillus↗

PubMed1998

Treatment results of 17 patients with diffuse pleural mesothelioma.

Treatment for diffuse pleural mesothelioma is very difficult. A retrospective study is established for analyzing the experiences in management of such a rare but fatal disease. From May 1960 to August 1996, 17 patients underwent treatment for pathologically confirmed malignant pleural mesothelioma at Veteran General Hospital-Taipei. The chart records were carefully reviewed and surgical specimens were reconfirmed by the pathologist. Single or combined treatment protocols with surgery, chemotherapy, and radiotherapy had been used according to the clinical situation. Pathological staging was recorded according to the Butchart staging system. Gender, smoking, asbestos exposure, histology, and survival were analyzed. There were 17 patients in total, including 15 males and 2 females with a mean age of 62 years. The most common symptoms were chest pain, cough, dyspnea and weight loss. For getting definite pathological diagnosis, the most sensitive procedures were video-assisted thoracic biopsy and open lung biopsy. In spite of trying multiple different treatment protocols, disease staging ( p = 0.0186) and the epithelial pathological type ( p = 0.0353) were the significant prognostic factors in our series. Prognosis of diffuse pleural mesothelioma is very poor. It was predominant in nen and no definite relationship with smoking or asbestos exposure was noted in our series, but it was relatively better in patients with early-stage and epithelial-type disease. Further efforts to improve the survival should be delivered on more aggressive cytoreductive surgery with early postoperative concurrent chemo-radiotherapy.

Adolescent↗

PubMed1998

Surgery for achalasia: long-term results in operated achalasic patients.

Achalasia is a functional disorder of the alimentary tract due to decreased or absent peristalsis of the esophageal body and obstructive outlet of the esophagus. Surgical treatment, eg. esophagomyotomy of the lower esophageal sphincter (LES), was one choice for resolving the problem and its effect was affirmative from reviews of many internationally authorized articles. However, few reports have ever questioned the long-term effects of it. From January 1968 to May 1996, 159 esophageal achalasic patients, 90 males and 69 females, were admitted due to dysphagia or food regurgitation. One hundred and forty-five patients had received 158 operations related to this benign motor disorder. The majority of patients received either modified Heller esophagomyotomy (M) or M plus modified Belsy Mark IV antireflux procedure (M+W) for primary treatment of their esophageal disorder, while conditional selection with addition of esophageal resection as advanced procedures for failure of primary surgery. We retrospectively studied these patients, collected their preoperative and postoperative clinical results, analyzed the causes of recurrent symptoms, compared the long-term results in different surgical procedures and searched for the pathogenesis of their failure. The results disclosed that the overall success rate for both methods was 73.1% with 85.7% for patients receiving M+W (56) and 64.9% of M (77) only. Through long-term follow-up, we had an improvement rate of 97.4% at an early stage and 53.3% for M at a late stage and 98.4% and 55.6% for M+W, respectively. The postoperative natural course of achalasic patients could be seen and progressive deterioration of the operated patients with time was noted. Several factors might contribute to the causes of unsuccessful surgery. We summarized them as incomplete myotomy, fused or healed myotomy, gastroesophageal reflux (GER), mucosal hernia and co-combined antireflux procedure by hypercalibrated or floppy wrapping. Esophagomyotomy or myotomy plus antireflux procedure for the esophagus could be concluded to rather effective in the long-term but palliative treatments for achalasia chronic deterioration of the results could be found for both of them. Defective myotomy and GER may be the major causes for their failure. The choice of types of surgery between M and M+W was not the cause of the unsuccessful results whereas the operative strategy and procedures would have a certain significance on the long-term effect.

Adolescent↗

PubMed1997

Glucose-dependency of bradykinin-induced insulin secretion from the perfused rat pancreas.

In order to investigate the glucose dependency of bradykinin (BK)-induced insulin secretion, rat pancreata were perfused in situ with BK (1 microM) for 30 min in the presence of glucose concentrations of 0 - 20 mM. Glucose (6 mM) alone maintained a steady baseline insulin secretion which was 6.7 %/- 0.5 ng/min (n = 4). The rate of insulin secretion in the presence of 0 and 1 mM glucose was approximately 70 - 80% and approximately 60-70% less, respectively, than in the presence of 6 mM glucose. The perfusate glucose concentrations of 10 and 20 mM induced a biphasic and dose-dependent insulin secretion, characterized by a transient increase followed by a sustained phase; the sustained phase was higher than the transient increase. BK failed to change insulin secretion in the absence of extracellular glucose. When BK was administered in 1 mM glucose, it induced a transient insulin release peak which was 2.8-fold of the insulin secretion induced by 6 mM glucose, then the insulin concentrations of the effluents decreased gradually to the levels that were slightly higher than that induced by the 1 mM glucose alone, but lower than that induced by 6 mM glucose. After BK was administered in 6 mM glucose, it induced a transient insulin release peak that was 3.6-fold of the baseline level, and followed by a sustained insulin secretion phase which was approximately 50% higher than that of the 6 mM glucose control group. When BK was perfused with 10 or 20mM glucose, it induced a similar insulin secretion pattern as in the glucose alone groups. However, the combination of glucose (10 or 20 mM) and BK induced a higher transient insulin release peak, which was 7.8- and 12-fold of the baseline level, respectively. Also, the BK-glucose-induced sustained phase was higher than the transient peak. BK caused a greater potentiation of insulin secretion in 20 mM glucose than in 10 mM glucose. Taken together, our findings suggest that 1) BK requires the presence of glucose to stimulate insulin secretion and 2) BK induces insulin secretion in a glucose concentration-dependent manner; the higher the glucose concentration, the greater the potentiation in BK-induced insulin secretion.

Animals↗

PubMed1997

The effect of bradykinin on secretion of insulin, glucagon, and somatostatin from the perfused rat pancreas.

To evaluate the effect of bradykinin (BK) on rat islet alpha, beta, and delta cells, the rat pancreas was perfused in situ with BK (1 mumol/L) for 30 minutes via a cannula placed in the celiac artery. Insulin, glucagon, and somatostatin concentrations in the effluent were measured to determine the effect of BK on the secretion of these hormones. The BK concentration of the rat pancreas was also measured. Basal secretion of insulin, glucagon, and somatostatin in medium containing 6 mmol/L glucose was maintained at 6.5 +/- 0.5 ng/mL 124 +/- 8 pg/mL, and 511 +/- 22 pg/mL (n = 12), respectively. BK (1 mumol/L) induced a transient peak that was 3.7-fold of the baseline concentration within 3 minutes, followed by a sustained level that was approximately 50% higher than baseline. BK also transiently increased glucagon secretion with a peak that was 1.7-fold of the baseline concentration within 3 minutes, without a sustained secretion phase. BK caused a reduction in somatostatin secretion within 3 minutes to a level of 60% to 70% of the baseline concentration. The BK concentration of the rat pancreas was 3.42 +/- 1.45 micrograms/g protein (n = 5), which was approximately 3 mumol/L. We concluded that BK stimulated insulin secretion, transiently increased glucagon secretion, and decreased somatostatin secretion during the 30-minute perfusion of the rat pancreas.

Analysis of Variance↗

PubMed1997

A gene encoding for an alpha-amylase from thermophilic Bacillus sp. strain TS-23 and its expression in Escherichia coli.

An alpha-amylase gene from Bacillus sp. strain TS-23 was cloned and expressed by using its own promoter on the recombinant plasmid pTS917 in Escherichia coli. A cell fractionation experiment revealed that approximately 60% of the amylase activity was in the periplasmic space. Analysis and activity staining of the concentrated supernatant fraction by SDS-polyacrylamide gel electrophoresis showed an apparent protein band with a mol. wt of approximately 65,000. The amylase gene (amyA) consisted of an open reading frame of 1,845 bp encoding a protein of 613 amino acids with a calculated mol. wt of 69,543. The predicted amino acid sequence showed high homology with Bacillus species, E. coli and Salmonella typhimurium alpha-amylases. Deletion of 96 amino acids from the C-terminal portion of the amylase did not result in the loss of amylolytic activity. The truncated amylase, deletion of the first 50 amino acids from the N-terminus, was overexpressed in E. coli system and refolded to yield an activable enzyme.

Amino Acid Sequence↗

PubMed1997

Lactose-induced expression of Bacillus sp. TS-23 amylase gene in Escherichia coli regulated by a T7 promoter.

Bacillus sp. TS-23 amylase gene was amplified by polymerase chain reaction and cloned into the pET23(+) transcription vector. Lactose induction of Escherichia coli BL21(DE3) cells harbouring this recombinant plasmid resulted in the extracellular production of gene products. By the addition of 20 mmol l-1 lactose, the amylase activity of fermentation broth had a specific activity of 21 U mg-1 of protein.

Bacillus↗

PubMed1997

Alpha2-adrenergic receptor-mediated Ca2+ influx and release in porcine myometrial cells.

We studied the mechanisms underlying alpha2-adrenergic receptor (AR)-mediated increase in intracellular free calcium ([Ca2+]i) in freshly dispersed myometrial cells from sows in the luteal phase of the estrous cycle. After the blockade of beta-ARs with propranolol, epinephrine increased [Ca2+]i dose-dependently in both the presence and absence of extracellular Ca2+. The rank order of alpha antagonists in inhibiting [Ca2+]i response to epinephrine was yohimbine > WB4101 >> prazosin in both the presence and absence of extracellular Ca2+, suggesting that epinephrine acts on alpha(2A)-ARs to increase Ca2+ influx as well as Ca2+ release from intracellular stores. Thapsigargin, the blocker of the Ca2+ pump in the sarcoplasmic reticulum, abolished the release but did not affect the influx. Pertussis toxin (PTX) inhibited the influx but failed to change the release. Nimodipine, an L-type Ca2+ channel blocker, nearly abolished the influx. The peak increase in [Ca2+]i caused by epinephrine was reached within 20 sec of administration. Intracellular cAMP concentrations were also decreased at 20 sec post-epinephrine. Epinephrine enhanced the L-type Ca2+ channel current, whereas forskolin suppressed it. Maximization of intracellular cAMP content by applying 8-bromo-cAMP (100 microM) blocked the effect of epinephrine on the current. U-73122, a phospholipase C inhibitor, reduced the Ca2+ release by epinephrine and oxytocin. Our results suggested that 1) activation of alpha2-ARs induces Ca2+ influx through opening L-type Ca2+ channels as well as inducing Ca2+ release from intracellular stores, and 2) a PTX-sensitive G protein couples negatively to adenylyl cyclase, leading to a decrease in cAMP formation which may be involved in the activation of Ca2+ channels. In addition, our results are consistent with the coupling of alpha2-ARs to a PTX-insensitive G protein (G(q)) to release Ca2+ from intracellular stores.

Adenylate Cyclase Toxin↗

PubMed1997

Ultrasound-guided fine needle aspiration biopsy in the diagnosis of chronic pulmonary infection.

Fourteen patients, with abnormalities on their chest radiographs found over a period of > or = 4 weeks and diagnosed as chronic pulmonary infections in the follow-up, underwent ultrasound-guided fine-needle aspiration biopsy (US-guided FNAB). Six patients also underwent color Doppler ultrasound examination before needle aspiration biopsy. Nine patients had a confirmed diagnosis [tuberculosis (n = 1), cryptococcosis (n = 3), actinomycosis (n = 2), and aspergillosis (n = 1)] or a suggestive diagnosis [caseating granulomatous inflammation (n = 1) and caseous necrosis (n = 1)] made after US-guided FNAB. The remaining 5 patients were finally diagnosed by US-guided large-bore cutting biopsy (n = 1, tuberculosis) and surgical resection [aspergillosis and organized pneumonia (n = 1), mucormycosis and organized pneumonia (n = 1), penicillium infection and organized pneumonia (n = 1), and cryptococcosis (n = 1)]. In 8 patients receiving gray scale US examination only, complications developed in 2 patients after US-guided FNAB [minimal pneumothorax (n = 1) and hemoptysis (n = 1)]. Of the 6 patients who also underwent color Doppler US examination, 4 had detectable blood vessels within the lesion. Thus, the site for US-guided FNAB was changed in 2 patients to prevent injury to prominent blood vessels. There were no complications observed following color Doppler US examination. We conclude that US-guided FNAB is useful for diagnosing chronic pulmonary infections, and color Doppler US is valuable for preventing injury to blood vessels.

Adult↗

PubMed1997

Surgical treatment of endobronchial tuberculosis.

The incidence of tuberculosis remains fairly high in some developing countries. Endobronchial tuberculosis may cause bronchostenosis, with potentially severe respiratory symptoms, atelectasis and secondary pneumonitis. Thirty-two surgically treated cases of tuberculous bronchostenosis (33 operations) are presented. In 13 cases-segmental resection or lobectomy was performed with bronchoplastic procedures. Anastomotic stenosis necessitated pneumonectomy 5 years later in one of the 13 and one patient had wound infection. Nineteen patients underwent pulmonary resection without bronchoplasty. Apart from the patient with anastomotic stenosis, all 32 were symptom-free in the follow-up period. Forced expiratory volume was significantly improved in the ten tested patients with bronchoplasty. The results suggest that surgical treatment is safe for endobronchial tuberculosis with poor response to specific chemotherapy. In addition to checking progression of the disease, bronchoplasty helps to preserve lung function. Appropriate chemotherapy should be given for 9-12 months perioperatively to prevent recurrence and restenosis.

Adolescent↗

PubMed1997

Lung injury related to consuming Sauropus androgynus vegetable.

BACKGROUND: Taking Sauropus androgynus, a Malaysian food, to reduce weight began as a fad in Taiwan in 1994. Some advocates of this fad developed pulmonary dysfunction. The aim of this study is to report the lung injury in patients taking Sauropus androgynus. METHODS: From July 1995 to November 1995, we investigated 104 nonsmoking patients (one male and 103 females) with chest roentgenography, pulmonary function, test, and Technetium 99m-labeled diethylene triamine penta-acetate (Tc-99m DTPA) radioaerosol inhalation lung scintigraphy. RESULTS: Among the 90 patients receiving Tc-99m DTPA inhalation lung scan, 46 (51.1%) patients had increased clearance of Tc-99m DTPA from lung and 20 (22.2%) patients had inhomogeneous deposition of the submicronic radioaerosol. Eighteen (18/100) patients had obstructive ventilatory impairment in pulmonary function test. Analyzing the results, we found that the patients with respiratory symptoms (n = 42) took more vegetables (p = 0.016), had increased clearance of Tc-99m DTPA (p = 0.010) and had lower FEV1 (p = 0.001), FEV1/FVC (p < 0.001), FEF25-75 (p = 0.001), VC (p = 0.002) and DLCO (p = 0.009) than the patients without respiratory symptoms (n = 62). FEV1 and FEV1/FVC were significantly reduced in patients with severe impairment of alveolar permeability. The cumulative dosage and duration of exposure were significantly associated with the reduction of FEV1 and FEV1/FVC. CONCLUSION: The lung injury after taking Sauropus androgynus involves alveoli and/or small airways and is manifest as obstructive ventilatory impairment with inhomogeneous aerosol distribution and increased lung epithelial permeability.

Adolescent↗

PubMed1997

Effect of U-73122 on calcium channel activity in porcine myometrial cells and pancreatic beta-cell line RINm5F.

AIM: To study the effect of U-73122, putative phospholipase C (PLC) inhibitor, on cytosolic Ca2+ concentration ([Ca2+]i) and voltage-dependent calcium channels (VDCC). METHODS: To record whole cell calcium current (ICa) by perforated patch-clamp and to measure cytosolic free calcium concentration ([Ca2+]i) with Fura-2. RESULTS: U-73122 inhibited KCl-induced and Bay-K-8644-induced increase in [Ca2+]i dose-dependently. U-73122 decreased markedly depolarization-induced ICa both in RINm5F and porcine myometrial cells in a concentration-dependent manner. The effect of U-73122 was more potent in porcine myometrial cells than that in RINm5F cells. U-73343 (an analog of U-73122), that does not inhibit PLC, also reduced the ICa by 50%. CONCLUSION: U-73122 inhibited VDCC and [Ca2+]i in both RINm5F and porcine myometrial cells.

Animals↗

PubMed1997

Leakage of intrathoracic oesophagovisceral anastomoses in adenocarcinoma of the gastric cardia: changes in serial APACHE II scores and their prognostic significance.

OBJECTIVE: To evaluate changes in serial Acute Physiology and Chronic Health Evaluation (APACHE) II scores in patients with intrathoracic oesophageal anastomotic leaks and to assess their prognostic significance. DESIGN: Retrospective study. SETTING: Teaching hospital, Taiwan. SUBJECTS: 18 patients (4%) who developed intrathoracic oesophageal anastomotic leaks in a total of 491 patients who underwent oesophagogastrectomy for adenocarcinoma of the gastric cardia between 1980 and 1994. MAIN OUTCOME MEASURE: APACHE II scores in those that survived (n = 10) compared with those who died (n = 8). RESULTS: Of the 18 patients, 8 (44%) died. The preoperative general condition, biochemical data, and perioperative APACHE II scores were similar in the two groups. Leakage from the oesophageal anastomoses caused similar degrees of sepsis in the two groups in terms of APACHE II scoring, but the APACHE II scores of survivors started to decline within a week of initial management. In contrast, the APACHE II scores of those who died had increased one week after the leak had been diagnosed despite initial management. There were significant differences in the APACHE II scores of survivors and those who died from one week after leakage until discharge or death (p < 0.001). Only one patient (1/9) survived if the APACHE II score one week after diagnosis of the leak was more than 10. None died of the leak if the APACHE II scores were equal to or less than 10 after a week. CONCLUSIONS: Adequate surgical drainage, antibiotic cover according to the microbiological picture, and nutritional support are essential in the management of intrathoracic oesophageal fistulas. Early reoperation to close early leaks by simple suture or secondary wrapping and to improve local drainage is recommended. The APACHE II scoring system is valuable in evaluating the severity of sepsis caused by intrathoracic oesophagovisceral anastomosis leaks and may serve as an indicator of adequate management. Aggressive surgical measures should be considered if APACHE II scores rise during initial management.

APACHE↗

PubMed1997

Mechanisms of bradykinin-induced insulin secretion in clonal beta cell line RINm5F.

We investigated the mechanisms underlying bradykinin (BK)-induced rise in intracellular Ca++ concentration [Ca++]i and insulin secretion using clonal beta cell line RINm5F. Incubation with a range of concentrations of BK increased in concentration-dependent manners both insulin secretion (BK of 10 nM to 10 microM) and [Ca++]i (BK of 100 nM to 100 microM). In Ca++-containing medium, BK (1 microM) induced a biphasic [Ca++]i rise, which was characterized by a Ca++ peak and a sustained Ca++ phase. In the Ca++-free medium, BK failed to increase insulin secretion and induced only a Ca++ peak without the sustained Ca++ phase. Thapsigargin (1 microM), an inhibitor of the Ca++ pump in the endoplasmic reticulum, abolished the Ca++ peak and the sustained phase. Nimodipine (1 microM), a voltage-dependent Ca++ channel blocker, abolished the BK-induced sustained Ca++ phase and inhibited BK-induced insulin release. The BK1 receptor agonist des-Arg9-BK (1 microM) did not change either [Ca++]i or insulin secretion. Both the BK-induced insulin secretion and rise in [Ca++]i were inhibited by a selective BK2 receptor antagonist, HOE 140 (3.3-100 nM), in concentration-dependent manners but were not by a BK1 receptor antagonist des-Arg9,Leu8-BK (1 microM). Pretreatment with pertussis toxin (0.1 microg/ml) did not block the BK-induced insulin secretion or increase in [Ca++]i. U-73122 (4, 6 and 8 microM), a phospholipase C inhibitor, antagonized both the BK-induced insulin secretion and the increase in [Ca++]i in a concentration-dependent and parallel manner. BK increased intracellular concentrations of inositol-1,4,5-trisphosphate (IP3). Neither (p-amylcinnamoyl)anthranilic acid (100 microM), a phospholipase A2 inhibitor, nor N(G)-nitro-L-arginine methylester (100 microM), a nitric oxide synthase inhibitor, inhibited these effects of BK. Taken together, these findings suggested that in beta cells, BK activates BK2 receptors, which, in turn, activate a pertussis toxin-insensitive G protein. The G protein couples to phospholipase C, which promotes the formation of IP3 and diacylglycerol. IP3 releases [Ca++]i from the intracellular Ca++ store, probably the endoplasmic reticulum, which triggers Ca++ influx via voltage-dependent Ca++ channels and thus increases insulin secretion.

Bradykinin↗