A fluorometric assay for measuring deamidase (lysosomal protective protein) using high-performance liquid chromatography

A rapid and sensitive assay method for the determination of deamidase activity is reported. This method is based on fluorometric detection of a dansylated dipeptide, 5-dimethylaminonaphthalene-1-sulfonyl-D-Tyr-Val (N-Dns-D-Tyr-Val), enzymatically formed from the substrate 5-dimethylaminonaphthalene-1-sulfonyl-D-Tyr-Val-NH2 (N-Dns-D-Tyr-Val-NH2), after separation by high-performance liquid chromatography (HPLC) using a C-18 reversed-phase column by isocratic elution. This method is sensitive enough to measure N-Dns-D-Tyr-Val at concentrations as low as 100 fmol, yields highly reproducible results and requires less than 8.5 min per sample for separation and quantitation. The optimum pH for deamidase activity was 4.0-4.5. Greater than 5 mM of reduced glutathione was needed for maximal enzyme activity. The Km and Vmax values were respectively 125 microM and 14.12 pmol/micrograms/h with the use of enzyme extract obtained from mouse spleen. Deamidase activity was strongly inhibited by Ag+, Cu2+, diisopropylfluorophosphate, and p-chloromercuriphenylsulfonic acid. Among the organs examined in a mouse, the highest specific activity of the enzyme was found in spleen. The sensitivity and selectivity of this method will aid in efforts to examine the physiological role of this enzyme.

[Outpatient chemotherapy with continuous infusion of 5-fluorouracil (CI 5-FU) and intravenous bolus leucovorin (IVB LV) in advanced gastrointestinal cancer: the second report]

This study was designed to evaluate the efficacy, toxicity, and quality of life (QOL) of outpatient chemotherapy with 5-FU and LV in advanced gastrointestinal cancer. Treatment consisted of CI 5-FU 450 mg/body/day, days 1-28, IVB LV 30 mg/body q wk (schedule, sch. A) and CI 5-FU 200 mg/m2/day, days 1-28, IVB LV 20 mg/m2 q wk (sch. B). 5-FU was administered with the Baxter infusor (0.5 ml/hr). Oral UFT (400-600 mg/day) was administered after these chemotherapy. Sixteen patients (pts) (sch. A 9 pts, sch. B 7 pts) with advanced gastrointestinal cancer have been treated to maintain the efficacy of prior inpatient chemotherapy. Twenty pts treated as adjuvant chemotherapy were added to evaluate toxicity and QOL. The median time to progression in sch. A was 3.0 months and sch. B was 2.4 months. Grade 3 or 4 toxicities of mucositis were seen 40% in sch. A and 0% in sch. B. Grade 1 or 2 skin toxicities were seen 100% in sch. A and 52% in sch. B. Mean score of QOL in sch. A was 78.0 +/- 11.5, sch. B was 89.5 +/- 7.8 ranked between inpatient chemotherapy (5-FU + CDDP 59.0 +/- 13.8) and UFT (91.8 +/- 6.1). In conclusion, these schedule of 5-FU and LV combination offers a high patient QOL and is suitable for advanced gastrointestinal cancer treatment.

[Marked bone marrow necrosis preceding acute monoblastic leukemia]

Bone marrow necrosis is rarely diagnosed during life but is more often seen at autopsy by accident. The prognosis of patients with bone marrow necrosis secondary to neoplastic disease is extremely poor. We described a 53-year-old man with bone marrow necrosis preceding acute monoblastic leukemia. He was admitted in June, 1994, for continuous back pain and marked elevation of serum lactate dehydrogenase. After admission, a hematologic examination showed progressive pancytopenia in peripheral blood and bone marrow necrosis. He was diagnosed as AML (M5) from the sudden appearance of leukemic blasts in the peripheral blood two months later. Induction therapy was immediately administered according to JALSG-92 protocol. The patient suffered from tumor lysis syndrome after chemotherapy, but complete remission was achieved by dialysis.

Structures of nine oxygenated 4-methylene sterols from Hachijo marine sponge Theonella swinhoei

Nine new sterols have been isolated from a marine sponge, Theonella swinhoei. Of these, seven sterols were found to be conicasterol derivatives [(24R)-4-methylene-24-methyl-8(14)-cholesten-3 beta-ol] oxygenated at carbon-7 and/or carbon-15. The other two were (24R)-7 beta,8 beta-epoxy-14 alpha-methoxy-4-methylene-24-methylcholestan- 3 beta-ol and (24R)-8,14-seco-8,14-dioxo-4-methylene-24-methylcholestan-3 beta-ol.

Monamidocin, a novel fibrinogen receptor antagonist. I. Production isolation, characterization and structural elucidation

Monamidocin, a novel fibrinogen receptor antagonist, has been isolated from the culture broth of Streptomyces sp. NR 0637 BY carbon adsorption, n-BuOH extraction, SP-Toyopearl, silica gel 60 silanised and Sephadex LH-20 column chromatographies and preparative HPLC. The molecular formula of monamidocin has been determined to be C15H22N4O4 from HRFAB-MS and 13C NMR spectral data. The structure of monamidocin has been determined to be N-[(S)-5-guanidino-2-hydroxypentanoyl]-L-phenylalanine by 2D NMR experiments.

[A case of surgical retrieve of migrated microcatheter]

This is a report of an accidental breakaway of a microcatheter during endovascular embolization for cerebral arteriovenous malformation occurring in a 48-year-old female. She had a sudden onset of cerebral herniated signs caused by a large hemorrhage in the region of the right parietal lobe. An angiogram showed a large arteriovenous malformation in the same region. 48 days after emergency evacuation of the hematoma and clipping of a feeding artery, we performed endovascular embolization using a microcatheter as assistant therapy for total removal of the nidus. However, accidentally, the microcatheter broke and migrated to the distal middle cerebral artery. Although we tried to retrieve the catheter using a loop snare, we had no success. We eventually retrieved it by open surgery next day. Fortunately the migrated catheter could be seen through a cortical artery, so after trapping it by using elastic thread and cutting off the artery we were able to extract the migrated catheter. Finally we were able to remove the nidus totally without other complications. Since breaking and migration of a microcatheter is a rare but possible accident, we should be prepared to cope with it appropriately.

Insulin resistance in skeletal muscle of the male Otsuka Long-Evans Tokushima Fatty rat, a new model of NIDDM

The Otsuka Long-Evans Tokushima Fatty rat is a new inbred obese strain with a late onset and chronic course of spontaneous hyperglycaemia in the male, and is considered to be a model of non-insulin-dependent diabetes mellitus [1, 2]. Fat distribution analysis showed a typical accumulation of intra-abdominal visceral fat in Otsuka Long-Evans Tokushima Fatty rats compared with a control strain, Long-Evans Tokushima Otsuka rats. To examine the insulin sensitivity of Otsuka Long-Evans Tokushima Fatty rats, we performed euglycaemic hyperinsulinaemic clamp experiments in vivo in rats under anaesthesia on this strain and on Long-Evans Tokushima Otsuka rats. The Otsuka Long-Evans Tokushima Fatty rats showed lower values for the glucose infusion rate (60% of the control at 12 weeks old and 20-30% of the control at 18, 24, 30 and 39 weeks old) than age-matched controls, indicating the development of insulin resistance with age. Hindlimb perfusion experiments in vitro also showed a 45% decrease of insulin-stimulated glucose uptake in Otsuka Long-Evens Tokushima Fatty rats in the diabetic stage. These results indicate that insulin resistance exists in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats. To obtain information on the mechanism of insulin resistance in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats, the insulin binding, autophosphorylation and tyrosine kinase activity of their partially-purified insulin receptors in vitro were compared with those from control rats. The results showed no marked differences in these insulin receptor functions between diabetic and control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural elucidation of aculeximycin. IV. Absolute structure of aculeximycin, belonging to a new class of macrolide antibiotics

Aculeximycin (1) produced by Streptosporangium albidum possesses a 30-membered polyhydroxy macrocyclic lactone and five sugars including aculexitriose. We have described the determination of the planar structure of N-diacetylated aculeximycin (2) using degradation products, which were obtained by DBU-methanol treatment, ozonolysis and periodative oxidation. In order to determine the relative and absolute configurations of aculeximycin, first, the relative and absolute configurations of the degradation products 10, 11, 12 and 13 were determined. Rychnovsky's method was very useful to determine the relative configurations of these degradation products, and CD exciton chirality and the modified Mosher's methods were applied to determine their absolute configurations. From these results, fourteen out of the twenty asymmetric centers in aculeximycin were determined to be 5S, 17R, 20S, 21R, 23R, 24R, 29S, 30R, 31S, 34R, 35S, 36S and 37R. The absolute configurations at C-14 and C-15 on the hemiketal ring were confirmed using 12 obtained by the partial glycol bond cleavage of 9. Absolute configurations of the remaining asymmetric centers were determined by spectral analysis of 15 and NOE experiment on 1. From these results, the absolute configuration of 1 was determined to be 5S, 7R, 10S, 11R, 14R, 15S, 17R, 19R, 20S, 21R, 23R, 24R, 25S, 29S, 30R, 31S, 34R, 35S, 36S and 37R.

[Expression of hepatocyte growth factor (HGF) in LEC rats at various phases of hepatitis and hepatoma]

The role of hepatocyte growth factor (HGF) in LEC rats were investigated at various phases of liver diseases by the detection of HGF expression, using ELISA assay, mRNA analysis and immunohistochemistry. Levels of plasma HGF increase in the fulminant hepatitis phase, decreased during chronic/cholangiofibrosis phase, and in some LEC rats, high levels of HGF were observed in hepatoma phase. HGF mRNA level in the liver was very high in fulminant hepatitis phase and low in chronic hepatitis phase. In hepatoma phase, HGF mRNA level was intermediate or high in the liver. In fulminant hepatitis phase, HGF mRNA level in the lung was slightly increased, while it was almost stable in the kidney in all the conditions studied. Immunohistochemical studies revealed that the frequency of HGF positive cells increased remarkably in fulminant hepatitis phase, and that many of them were located at the portal triads. Fewer HGF-positive cells were found in chronic hepatitis phase and were not found in the tissue of cholangiofibrosis. HGF was found in the surface of hepatocellular carcinoma cells and in the cytoplasm of the non-epithelial cells in cancerous liver tissues. HGF-positive cells appeared 24h after partial hepatectomy, diffusely, and HGF mRNA increased earlier in the kidney and lung than in the liver. Moreover, HGF mRNA level was higher in the lung than in the liver. These results suggest that in the natural course of spontaneous hepatitis and hepatoma in LEC rats, HGF is expressed mainly in the liver and that HGF may play an important role in the regeneration of hepatocytes in a paracrine manner. In contrast, after partial hepatectomy, HGF produced in the lung may be effective for liver regeneration in an endocrine manner.

Mechanisms of the potent and long-lasting antihypertensive action of the new calcium channel blocker pranidipine. Evidence for strong affinity to the calcium channels or membranes

To elucidate the mechanisms of the potent and long-lasting antihypertensive action of pranidipine (CAS 99522-79-9, OPC-13340), a wash-out experiment in isolated rat aorta preparations and a displacement binding experiment of (+)[3H]PN200-110 (isradipine) with pranidipine and other dihydropyridines to porcine skeletal T-tubules was conducted. It was revealed that the inhibition of KCl-induced contraction by pranidipine remained complete even after washing out the drug 9 times. Also, pranidipine had the lowest Ki value for (+)[3H]PN200-110 binding in skeletal T-tubules. The lipophilicity of pranidipine measured by octanol-buffer partition coefficient was the highest among the tested compounds, and the order of lipophilicity coincided with the order of potency in the displacement binding experiments. These results suggest that pranidipine has a very high affinity to Ca channels or to T-tubule membranes, and strongly support the "membrane-bilayer pathway hypothesis" which assumes the partitioning of the drug into the lipid bilayer before drug binding to Ca channels as an explanation of the potent and long-lasting action of pranidipine compared with other dihydropyridines.

Mice deficient for the IL-3/GM-CSF/IL-5 beta c receptor exhibit lung pathology and impaired immune response, while beta IL3 receptor-deficient mice are normal

The receptors for IL-3, GM-CSF, and IL-5 share a common beta subunit (beta c), and mice have an additional IL-3 beta subunit (beta IL3). We have independently generated mice carrying null mutations of each molecule. beta c mutant bone marrow showed no response to GM-CSF or IL-5, whereas IL-3 stimulation of beta c or beta IL3 mutant bone marrow was normal. beta c mutant mice showed lung pathology consisting of lymphocytic infiltration and areas resembling alveolar proteinosis, and also exhibited low basal numbers of eosinophils. Infection of beta c mutant mice by Nippostrongylus brasiliensis resulted in the absence of blood and lung eosinophilia. Animals repopulated with beta c mutant bone marrow cells showed slower leukocyte recovery and reduced eosinophil numbers. These data define the role of beta c in vivo, and show a phenotype that is likely to be the cumulative effect of loss of GM-CSF and IL-5 stimulation.

[Proton MR spectroscopy in patients with unilateral temporal lobe epilepsy]

The authors assessed proton magnetic resonance spectroscopy (1H-MRS) in patients with unilateral refractory temporal bole epilepsy. The subjects consisted of 20 patients (those with brain tumors, trauma, malformations or definite organic lesions were excluded) and 10 normal volunteers. 1H-MRS and MRI were performed using a 1.5 tesla machine. 1H-MRS was achieved using point-resolved spectroscopy (PRESS) or the stimulated echo acquisition mode (STEAM), and a 3 x 3 x 3 cm volume of interest was positioned at the hippocampus. N-Acetyl-aspartate (NAA) and choline-containing substance (Cho) signals were evaluated. The results showed decreased NAA and elevated Cho or asymmetry of both NAA and Cho in the epileptogenic focus in 19/20 cases. The reductions in NAA presumably reflect neuronal loss, while the elevation of Cho probably represents membrane break down within the lesion. These abnormalities were observed in 19/20 cases (95%), whereas abnormal magnetic resonance imaging was detected in only 6/20 (30%) of the patients. Thus, 1H-MRS appears to be a useful, non-invasive modality for evaluating metabolic changes in epileptogenic foci, and these metabolic changes can serve as a more sensitive indicator than magnetic resonance imaging.

Differing distribution of hepatocyte growth factor-positive cells in the liver of LEC rats with acute hepatitis, chronic hepatitis and hepatoma

Using anti-rat hepatocyte growth factor (HGF) antibody, we investigated the distribution of HGF-positive cells in the liver tissues of LEC rats at various phases of liver diseases. During the phase of fulminant hepatitis, HGF-positive cells increased remarkably, and many of them were localized at the portal triads; these cells were identified from their shape as non-epithelial cells. A reduced number of HGF-positive cells was observed during the phase of chronic hepatitis, while no HGF-positive cells were seen in the tissue of cholangiofibrosis. During the phase of carcinoma, staining revealed that both the hepatocellular carcinoma cells and the non-epithelial cells in cancerous liver tissue were HGF-positive. These results suggest that, in LEC rats, HGF may play an important role in the regeneration of hepatocytes as well as in the development of hepatocellular carcinoma.

Panclicins, novel pancreatic lipase inhibitors. II. Structural elucidation

Panclicins A-E are novel and potent pancreatic lipase inhibitors produced by Streptomyces sp. NR 0619. Their structures have been elucidated based on NMR and FAB-MS experiments. The relative configurations have also been determined by NMR experiments. The absolute stereochemistry has been determined by the chiral HPLC analysis of the hydrolysates of panclicins A and B and by modified Mosher's method on a derivative of panclicin A. They are structurally related to beta-lactone esterase inhibitors of microbial origin, lipstatin, valilactone, ebelactones and esterastin. Panclicins also contain a beta-lactone structure with two alkyl chains, one of which has an N-formylalanyloxy or N-formylglycyloxy substituent.

[Surgical treatment for ossification of the posterior longitudinal ligament of the cervical spine]

The surgical results in 37 patients with cervical myelopathy due to ossification of the posterior longitudinal ligament of the cervical spine were described. This series consisted of 32 patients who underwent anterior decompression with anterior cervical fusion using bone grafts obtained from cervical vertebral bodies, and 5 patients who underwent expansive laminoplasty or laminectomy as a method of posterior decompression. 6 out of 32 patients with anterior cervical fusion were operated on at one level, 18 at two levels and 8 at three levels. The patients were out of bed within two days and treated using a soft collar for 3 months. In all patients, the symptoms improved postoperatively. Postoperative X-ray films showed solid bone fusion in all patients with anterior cervical fusion at a mean follow up time of one year and nine months (range 6 months to 3 years 6 months). Anterior angulation was found in one (3%) out of 32 patients who underwent anterior cervical fusion. Concerning the method of operation, the authors think that anterior decompression is to be recommended for cases with ossification within three consecutive vertebrae and posterior decompression should be applied to cases in which anterior decompression is very difficult. If necessary, a two-stage combined decompression is recommended.

Fatty acid hydroxylase of the fungus Fusarium oxysporum is possibly a fused protein of cytochrome P-450 and its reductase

Fatty acid subterminal (omega-1 approximately omega-3) hydroxylase of the fungus Fusarium oxysporum was solubilized from the microsomal fraction and partially purified. The hydroxylase activity was recovered into a single active fraction, and its spectral nature showed the presence of cytochrome P-450 (P-450). Fatty acid hydroxylase activity was markedly restored upon addition of FAD, FMN, and/or hemin to the eluted fraction. The fraction also exhibited other properties characteristic of both a hemeprotein and a flavin-containing reductase. These results are highly indicative that the fungal hydroxylase is a fused protein containing both P-450 and its reductase domains. In this aspect the fungal enzyme resembles bacterial P-450BM3, although it is membrane-bound unlike the bacterial counterpart.

Evaluation of the patency of an extracranial-intracranial bypass using magnetic resonance angiography with selective presaturation of bypass vessels

Three-dimensional time-of-flight magnetic resonance (MR) angiography using radiofrequency presaturation pulses was used to evaluate the patency of extracranial-intracranial (EC/IC) bypass in 11 patients. Presaturation causes signal loss in the vascular territory supplied by the presaturated EC/IC bypass graft. In all patients with a patent EC/IC bypass graft confirmed on conventional angiography, disappearance of the signal of the middle cerebral artery receiving blood flow from the bypass graft was clearly observed on MR angiograms with presaturation, indicating patency of the EC/IC bypass graft. MR angiography with presaturation pulses is a noninvasive and repeatable method for evaluation of the function of an EC/IC bypass graft.

[Effects of pranidipine (OPC-13340), a novel 1,4-dihydropyridine derivative Ca-antagonist, on isolated porcine coronary contraction and acute myocardial ischemia in the pig]

Pranidipine (OPC-13340) is a novel, potent and long-acting 1,4-dihydropyridine derivative Ca-antagonist being developed for clinical use as an antihypertensive and antianginal drug. Pranidipine at concentrations of 10(-9) - 10(-6) M suppressed the contraction induced by serotonin (10(-8) - 10(-5) M) or histamine (10(-8) - 10(-4) M) in isolated porcine coronary arteries in a non-competitive and concentration-dependent manner. The potency of this effect of pranidipine was almost similar to that of nifedipine. In anesthetized open-chest pigs with coronary artery occlusion, pranidipine at a dose of 10 micrograms/kg, i.v. lowered blood pressure and increased heart rate, peak dP/dt and % segment shortening of the non-ischemic zone before occlusion. Pranidipine inhibited the ST elevation of the electrocardiogram and the increase in left ventricular end-diastolic pressure during ischemia. These results suggest that pranidipine might relieve symptoms via inhibition of coronary spasm and reduce myocardial ischemia due to reduction of both preload (left ventricular end-diastolic pressure) and afterload (blood pressure).

Effect of vagotomy on hyperactivity and increased dopamine turnover induced by intraperitoneal administration of thyrotropin-releasing hormone

Thyrotropin-releasing hormone (TRH) injected intraperitoneally at doses of 10 mg/kg and 20 mg/kg induced marked hyperactivity in rats. Although regional levels of brain dopamine and its metabolites (DOPAC and HVA) in vagotomized rats did not differ from those in sham-operated controls, the (DOPAC + HVA)/dopamine ratio, an indicator of dopamine turnover, was significantly higher in the nucleus accumbens of TRH-treated sham-operated rats than that in untreated sham-operated controls. TRH injection induced hyperactivity only in sham-operated rats and not in subdiaphragmatic bilaterally vagotomized rats. Similarly, bilateral vagotomy completely abolished the TRH-induced increases in dopaminergic turnover in the nucleus accumbens. These results suggest that the dopaminergic system in the nucleus accumbens is involved in hyperactivity induced by TRH, and that TRH mainly affects peripheral receptors. The vagal nerve may be the major pathway from the visceral organs to the brain involved in the etiology of hyperactivity.

Cyclothialidine, a novel DNA gyrase inhibitor. II. Isolation, characterization and structure elucidation

Cyclothialidine is a novel DNA gyrase inhibitor produced by Streptomyces filipinensis NR 0484. It was isolated from the culture broth by charcoal adsorption, Diaion HP-21, Amberlite CG-50, DEAE Toyopearl, and Toyopearl HW-40 SF column chromatography. The structure of cyclothialidine was determined to be a unique twelve membered lactone by amino acid analysis and various 2D-NMR experiments. Cyclothialidine inhibited Escherichia coli DNA gyrase with an IC50 of 30 ng/ml.

Hispidospermidin, a novel phospholipase C inhibitor produced by Chaetosphaeronema hispidulum (Cda) Moesz NR 7127. II. Isolation, characterization and structural elucidation

Hispidospermidin (1) is a novel phospholipase C inhibitor produced by Chaetosphaeronema hispidulum (Cda) Moesz NR 7127. Its structure (C25H47N3O) has been elucidated as a cage compound with a trimethylspermidine side chain based on various NMR studies, including 1H-1H COSY, 13C-1H COSY, HOHAHA, HMBC, COLOC and long range J C-H resolved 2D spectroscopy. The absolute configuration of 1 has been elucidated by modified Mosher's method on the (R)- and (S)-MTPA amides of a derivative of 1.

Ro 09-1470 is a selective inhibitor of P-450 lanosterol C-14 demethylase of fungi

Ro 09-1470 is a new antifungal agent that belongs to a series of compounds characterized by a tetrahydropyran skeleton with glycine and alkenyl side chains and that inhibits P-450 lanosterol C-14 demethylase (P-450(14DM)) of fungi (Y. Aoki, T. Yamazaki, M. Kondoh, Y. Sudoh, N. Nakayama, Y. Sekine, H. Shimada, and M. Arisawa, J. Antibiot. 45:160-170, 1992; S. Matsukuma, T. Ohtsuka, H. Kotaki, H. Sawairi, T. Sano, K. Watanabe, N. Nakayama, Y. Itezono, M. Fujiu, N. Shimma, K. Yokose, and T. Okuda, J. Antibiot. 45:151-159, 1992). We have studied the compound's mode of interaction with fungal P-450(14DM) and its selectivity for the fungal versus mammalian P-450 enzymes. Ro 09-1470 bound to the Saccharomyces cerevisiae P-450(14DM) by coordinating to the heme with one-to-one stoichiometry. Unlike the azole compounds, it interacted with both ferric and ferrous heme. It was active also against the P-450(14DM) of Candida albicans. Ro 09-1470 preferentially inhibited the yeast P-450(14DM), showing a 50% inhibitory concentration (IC50) of 0.47 to approximately 1.1 microM, which is much lower than the IC50s for rat hepatic P-450s catalyzing cholesterol biosynthesis (IC50 = 341 microM), p-nitroanisol O-demethylation (> 1,000 microM), aniline hydroxylation (> 1,000 microM), and aminopyrine N-demethylation (920 microM). The degree of selectivity for yeast P-450 was higher than that of ketoconazole.

Effects of the new long-acting dihydropyridine calcium antagonist pranidipine on the endothelium-dependent relaxation in isolated rat aorta in vitro

The action of methyl 3-phenyl-2 (E)-propenyl 1,4-dihydro-2,6-dimethyl- 4-(3-nitrophenyl)-3,5-pyridinedicarboxylate (pranidipine, OPC-13340, CAS 99522-79-9) on the endothelium-dependent relaxation in the isolated aorta in vitro was examined in comparison with other calcium antagonists (nifedipine, nitrendipine, nicardipine, diltiazem and verapamil). In the isolated aortic preparation of Wistar rats, acetylcholine (10(-5) mol/l), ATP (10(-5) mol/l or histamine (10(-5)-10(-4) mol/l) caused endothelium-dependent relaxation when the strips were previously contracted with prostaglandin F2 alpha. This endothelium-dependent relaxation recovered within a few minutes, although the mechanisms of this contraction after relaxation were not clear. The pretreatment with pranidipine for 20 min extended the duration of the endothelium-dependent relaxation, however, there was no potentiation in magnitude of the relaxation. This effect on the duration of endothelium-dependent relaxation was prominent in pranidipine, namely, other calcium antagonists tested had not this action at clinical concentrations. This phenomenon was also observed when the strips were pre-contracted with norepinephrine. This action of pranidipine might be some beneficial feature for therapeutic use of the compound.