Pharmacological characterization of a nonpeptide bradykinin B2 receptor antagonist, FR165649, and agonist, FR190997

1. The nonpeptide bradykinin (BK) B2 receptor antagonist, FR165649 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacetyl ]-N-methylamino]benzyloxy]-2-methylquinoline), and agonist, FR190997 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl) cinnamidoacetyl]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridyl methoxy)quinoline) have been identified. These compounds have a common chemical structure, and the 2-pyridylmethoxy group is the only structural difference between them. 2. Both FR165649 and FR190997 displaced [3H]-BK binding to B2 receptors in guinea-pig ileum membranes, with an IC50 of 4.7 x 10(-10) M and 1.5 x 10(-9) M, respectively. They also displaced [3H]-BK binding to B2 receptors in human lung fibroblast IMR-90 cells, with an IC50 of 1.6 x 10(-9) M and 9.8 x 10(-10) M, respectively. 3. In guinea-pig isolated ileum-preparations, FR165649 had no agonistic effect on contraction and caused parallel rightward shifts of the concentration-response curves to BK on contraction. Analysis of the data produced a nominal pA2 value of 9.2+/-0.1 (n=5) and a slope of 1.4+/-0.1 (n=5). On the other hand, FR190997 induced concentration-dependent contraction of guinea-pig ilea with a pD2 of 7.9+/-0.2 and the contraction was inhibited by a specific peptide bradykinin B2 receptor antagonist, Hoe 140 (D-Arg-[Hyp3, Thi5, D-Tic7, Oic8]BK) in a non-competitive manner. 4. In IMR-90 cells, FR165649 had no agonistic effect on phosphatidyl inositol (PI) hydrolysis and caused parallel rightward shifts (approximately 200 fold shift at 10(-7) M) of the concentration-response curves to BK on PI hydrolysis. FR190997 induced concentration-dependent PI hydrolysis in IMR-90 cells with a pD2 of 8.4+/-0.1, and this effect was inhibited by Hoe 140. 5. These results indicate that FR165649 and FR190997 are, respectively, a potent bradykinin B2 receptor antagonist and agonist, and that the agonistic activity depends on the small part of the nonpeptide ligand. FR165649 and FR190997 may be useful tools for studying the relationship between ligands and receptors.

Production of mice deficient in genes for interleukin (IL)-1alpha, IL-1beta, IL-1alpha/beta, and IL-1 receptor antagonist shows that IL-1beta is crucial in turpentine-induced fever development and glucocorticoid secretion

Interleukin (IL)-1 is a major mediator of inflammation and exerts pleiotropic effects on the neuro-immuno-endocrine system. To elucidate pathophysiological roles of IL-1, we have first produced IL-1alpha/beta doubly deficient (KO) mice together with mice deficient in either the IL-1alpha, IL-1beta, or IL-1 receptor antagonist (IL-1ra) genes. These mice were born healthy, and their growth was normal except for IL-1ra KO mice, which showed growth retardation after weaning. Fever development upon injection with turpentine was suppressed in IL-1beta as well as IL-1alpha/beta KO mice, but not in IL-1alpha KO mice, whereas IL-1ra KO mice showed an elevated response. At this time, expression of IL-1beta mRNA in the diencephalon decreased 1.5-fold in IL-1alpha KO mice, whereas expression of IL-1alpha mRNA decreased >30-fold in IL-1beta KO mice, suggesting mutual induction between IL-1alpha and IL-1beta. This mutual induction was also suggested in peritoneal macrophages stimulated with lipopolysaccharide in vitro. In IL-1beta KO mice treated with turpentine, the induction of cyclooxygenase-2 (EC 1.14.99.1) in the diencephalon was suppressed, whereas it was enhanced in IL-1ra KO mice. We also found that glucocorticoid induction 8 h after turpentine treatment was suppressed in IL-1beta but not IL-1alpha KO mice. These observations suggest that IL-1beta but not IL-1alpha is crucial in febrile and neuro-immuno-endocrine responses, and that this is because IL-1alpha expression in the brain is dependent on IL-1beta. The importance of IL-1ra both in normal physiology and under stress is also suggested.

Influence of cellular incorporation of n-3 eicosapentaenoic acid on intracellular Ca2+ concentration and membrane potential in vascular smooth muscle cells

Long-term treatment with n-3 eicosapentaenoic acid (EPA) has been shown to exert hypotensive effects and have beneficial effects on atherosclerosis. To elucidate one of the underlying mechanisms of these effects, intracellular calcium concentration [Ca2+]i, and resting membrane potential were measured in rat vascular smooth muscle cells (A7r5 cell) treated with EPA, using Ca2+-sensitive dye fura-2 AM and the patch clamp technique. The alterations in fatty acid compositions of phospholipids and cell migration after treatment with EPA (30 microM) for 6 h-7 days were also examined. After treating cells with EPA, the EPA and DPA (docosapentaenoic acid) content of the phospholipid fraction (mol.%) increased in a time-dependent manner. Alternatively, arachidonic acid (AA) decreased, and then the ratio of EPA and AA (EPA/AA) increased significantly. The resting [Ca2+]i decreased from 170 +/- 46 nM (n = 16) in control cells to 123 +/- 29 nM (n = 16) in cells treated with EPA (30 microM) for 7 days. Vasopressin (100 nM), endothelin-1 (100 nM) and platelet-derived growth factor (PDGF 5 ng/ml) evoked an initial peak of [Ca2+]i, followed by a smaller sustained rise of [Ca2+]i in the presence of extracellular Ca2+. In EPA-treated cells, both the peak and the sustained rise of [Ca2+]i induced by these agonists decreased in comparison to the control cells. EPA treatment also decreased the transient [Ca2+]i rise evoked by these agonists in the absence of extracellular Ca2+. Under the current clamp condition, resting membrane potential was significantly higher in EPA-treated cells (-49.8 +/- 10.4 mV, n = 41) than in control cells (-44.6 +/- 7.4 mV, n = 41, P < 0.05), and the input resistance of the cell was lower in EPA-treated cells, while cell size and capacitance were not statistically different. In addition, long-term treatment with EPA for 7 days significantly inhibited PDGF-induced cell migration. These results suggest that cellular incorporation of n-3 eicosapentaenoic acid attenuates intracellular mechanisms related to changes of [Ca2+]i and affects membrane potential, thereby inhibiting migration of vascular smooth muscle cells. These actions of EPA may contribute to its vasorelaxant and antiatherosclerotic effects.

Abnormality of very long-chain fatty acids of erythrocyte membrane in alcoholic patients

Profiles of very long-chain fatty acids were studied in the erythrocyte membrane of five alcoholic patients. We identified three fatty acids as cis-16-pentacosenoic acid (C25:1), cis-17-hexacosenoic acid (C26:1), and hexacosenoic acid (C26:1), and hexacosanoic acid (C26:0) by gas chromatography-mass spectrometry. The ratios of C26:1/C22:0, C26:0/C22:0, C24:1/C22:0, and C24:0/C22:0 were increased. These findings suggest that active oxygen species or free radicals generated by chronic alcohol consumption in alcohol patients interrupt the peroxisomal beta-oxidation of fatty acids, because very long-chain fatty acids are mainly metabolized by the peroxisomal beta-oxidation system. This is the first study showing accumulation of very long-chain fatty acids in the erythrocyte membrane of alcoholic patients.

Molecular maturation and functional expression of mouse polymeric immunoglobulin receptor

Mouse polymeric immunoglobulin receptor (pIgR) cDNA was stably introduced into a hamster-derived fibroblastic cell line, Chinese hamster ovary (CHO) cell, by the calcium phosphate method. Surface expression of pIgR was detected by immunostaining and FACS analysis. The immunoprecipitated products of cell lysates revealed that the molecular mass of the most mature form of pIgR was approximately 120 kDa. Western blotting and metabolic labeling experiments followed by immunoprecipitation with an anti-mouse secretory component (SC) Ab demonstrated the existence of a 110 kDa immature form of pIgR. The reason for the existence of two forms of pIgR molecule was examined by conducting pulse-chase experiments which revealed the pIgR underwent molecular maturation. During this process, the 110 kDa form of pIgR was converted into a 120 kDa form by glycosylation. Moreover, tunicamycin treatment revealed the core form of pIgR had a molecular mass of approximately 100 kDa. The pIgR expressed on the surface of the transfectant could specifically bind and take up mouse polymeric IgA (MOPC 315), suggesting that, at least in this mouse system, cell type-specific molecules are not necessary for surface pIgR expression and polymeric immunoglobulin (pIg) binding and uptake.

Presence of polysialic acid and HNK-1 carbohydrate on brain glycoproteins from beta-1,4-galactosyltransferase-knockout mice

Polysialic acid and HNK-1 carbohydrate are expressed on Gal beta 1-->4GlcNAc outer chains of N-linked sugar chain of neural cell recognition molecules at certain developmental stages and involved in neural tissue formation. Targeted inactivation of the mouse beta-1,4-galactosyltransferase (beta-1,4-GalT) gene resulted in short life of the mice which supposedly do not have such carbohydrate antigens but have no defects in neural tissue formation. Analysis of the mutant mouse brain glycoproteins revealed that polysialic acid and HNK-1 carbohydrate are normally expressed in an age-dependent manner. In support of this, protein bands reacted with Ricinus communis agglutinin-I, which interacts with oligosaccharides terminated with the Gal beta 1-->4GlcNAc group, and beta-1,4-GalT activity toward GlcNAc beta-S-pNP were detected in the mutant mouse brain, indicating that brain contains another functional beta-1,4-GalT important for the expression of the carbohydrate antigens.

Serum copper and ceruloplasmin activity at the early growing stage in foals

Serum concentrations of copper (Cu), zinc (Zn), manganese (Mn), calcium (Ca) and inorganic phosphorus (P), as well as antigenic ceruloplasmin (Cp) and oxidase activity as a functional index for copper metabolism, were measured in 10 foals (5 males and 5 females) and their dams. Samples were harvested from the foals within 1 wk after birth and monthly from 1 to 17 mo of age. Samples were collected from their dams in the perinatal period (monthly from 2 mo before delivery to 5 mo postpartum). Serum oxidase activity, antigenic Cp and Cu in foals were extremely low at 1 wk. Serum Cp had the lowest value of 17.0 +/- 8.0 (mean +/- SD) mg/dL within the 1st wk, then increased rapidly up to 43.7 +/- 5.8 mg/dL at 1 mo, and maintained this level until the 17th mo. Serum Zn in foals had the highest value of 73.2 +/- 13.1 micrograms/dL within 1 wk, then decreased to 38.3 +/- 5.9 micrograms/dL by 17 mo. Serum Mn, Ca and P in mares were almost stable and within established reference ranges for our laboratory in the perinatal period, and these values in foals were also in the normal range. Even on appropriate feeding, serum Cu, Cp and oxidase activity were quite low a few weeks after birth, while a higher proportion of Cp-binding copper was found in the foals. This might be caused by the limited synthesis of ceruloplasmin in this period. These data suggest that newborn foals are in a critical situation of marginal copper status in the early stage of growth.

Internal thoracic-carotid bypass surgery for Takayasu's arteritis

BACKGROUND

Various carotid reconstructions have been used in Takayasu's arteritis (TA) to relieve brain ischemic insult. The indications and guidelines for surgical management, however, have remained poorly defined. The authors present a new reconstructive procedure using the sequential internal thoracic artery (ITA) as the donor for bypass surgery to supplement the cerebral blood flow.

CASE DESCRIPTION

A 38-year-old woman presented with three episodes of syncope. The patient was admitted to our hospital and was diagnosed with TA. Before the operation, the patient was designated to undergo aortocarotid bypass using saphenous veins. However, a dilated ascending aorta with an extremely thin wall made it impossible. Finally, we decided to use the ITA as the donor for bypass surgery. This patient is now free of cerebral ischemic insult 8 months after the operation.

CONCLUSION

Although the procedure is still at a preliminary stage, a successful case is briefly described.

An anti-human VEGF monoclonal antibody, MV833, that exhibits potent anti-tumor activity in vivo

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor for tumor angiogenesis and growth. We previously established the immunoneutralizing monoclonal antibodies (MAbs) to human VEGF, and showed that MV101 (IgG1) and MV303 (IgG2a) inhibited the growth of human solid tumor xenografts in nude mice. Then, we tried to develop another immunoneutralizing anti-VEGF MAb that exhibited more potent antitumor activity than MV101 or MV303. We obtained more than 140 clones of hybridomas that were producing anti-VEGF MAb from the mice immunized with recombinant human VEGF121. Among them, 26 clones showed the immunoneutralizing activity and MV833 possessed the most potent antitumor activity in vivo. A total of 9 i.p. administrations of 25 microg of MV833 inhibited the growth of human fibrosarcoma HT-1080 solid tumor xenografted in nude mice more potently than MV101 or MV303. Moreover, only 1 i.v. administration of 100 microg of MV833 on Day 1 after tumor inoculation also significantly inhibited the growth of HT-1080 in vivo, whereas MV101 and MV303 did not. All three MAbs inhibited the growth of human umbilical vein endothelial cells (HUVEC) induced by VEGF121 and the binding of 125I-labeled VEGF121 to HUVEC to a similar extent. The binding of MV101 and MV303 to VEGF121 was cross-competitive; however, MV833 weakly competed with the binding of MV101 to VEGF121. These findings indicated that MV833 recognized the region(s) of VEGF differently than MV101 or MV303, and this difference contributed to the superiority of antitumor activity of MV833.

[Color Doppler signal enhancement with SH/TH-508 in pancreatic tumors]

In this report, we showed the efficacy of a new contrast agent (SH/TA-508, Schering AG, Germany) for color Doppler imaging of the pancreatic tumors. In pancreatic ductal cancer, no enhancement of the lesion was observed, but vascular invasion by cancer became to be easily evaluated. On the other hand, hypervascular tumors such as islet cell tumor and cystadenocarcinoma, were increased in color Doppler signals of vessels by SH/TA-508. We concluded that SH/TA-508 was useful for evaluating the vascular invasion by pancreatic cancer as well as vascularity of hypervascular mass and solid component of cystic neoplasma.

Increase in serum vascular endothelial growth factor levels during altitude training

The present study was performed to evaluate the effects of physical exercise at altitudes on serum vascular endothelial growth factor (VEGF) levels. Eight subjects underwent intensive swimming training for 21 days at 1886 m. After altitude training commenced, red blood cell (RBC) counts and erythropoietin levels increased, but both haemoglobin and haematocrit levels did not change significantly. The serum level of VEGF, measured by means of a highly sensitive chemiluminescence (ELISA), showed a transient decrease 10 days after start of the altitude training, thereafter increasing significantly to reach a peak level 19 days later, rising from 23.0 +/- 5.3 to 46.0 +/- 14.6 pg mL-1 (P < 0.05 vs. before). On return to low altitude in Japan, the level of VEGF decreased, and 1 month later had returned to initial levels. Endurance training at altitudes increases serum VEGF levels; this could be an adaptive reaction to hypoxic conditions. This result suggests that VEGF may provide a new physiological parameter for hypoxic stress imposed by high altitude training.

Significance of circulating hepatocyte growth factor level as a prognostic indicator in primary breast cancer

The circulating hepatocyte growth factor (HGF)/scatter factor level is frequently increased in advanced cancer patients. In this study, we have assessed the prognostic value of the circulating HGF level determined by enzymatic immunoassay in primary breast cancer patients. Of 200 primary breast cancer patients, 54 (27.0%) showed the increase of serum HGF level according to the age-matched cutoff values. The prognosis of the patients with the increased HGF level was statistically worse than that of the patients with normal HGF level (P = 0.0001, log-rank test). Multivariate analysis confirmed that the increase in HGF level was an independent prognostic indicator in primary breast cancer patients. In the background analysis, the increase in serum HGF level was significantly associated with tumor size, nodal status, and histological evidence of venous invasion. The data indicate that up-regulation of the circulating HGF level may predict systemic tumor spread and early relapse in primary breast cancer patients.

A novel class of orally active non-peptide bradykinin B2 receptor antagonists. 1. Construction of the basic framework

A novel class of potent, selective, and orally active non-peptide bradykinin (BK) B2 receptor antagonists were designed and synthesized starting from 8-benzyloxyimidazo[1,2-a]pyridine derivative 2. The unique screening lead (2) was discovered by a two-step intentional random screening process, involving recognition of the relationship between BK and angiotensin II (Ang II) and the common structural features. Systematic chemical modification of 2 elucidated the structural requirements essential for B2 binding affinity leading to the identification of 8-[[3-(N-acylglycyl-N-methylamino)-2,6-dichlorobenzyl]oxy]-3-halo- 2- methylimidazo[1,2-a]pyridine skeleton as the basic framework of this new series of B2 antagonists. A molecular modeling study suggested the key role of the N-methylanilide moiety at the 3-position of the 2,6-dichlorobenzene ring to allow these compounds to adopt the characteristic active conformation. The representative lead compounds inhibited the specific binding of [3H]BK to guinea pig ileum membrane preparations expressing B2 receptors, with nanomolar IC50S and also displayed in vivo functional antagonistic activities against BK-induced bronchoconstriction in guinea pigs at an oral dose of 1 mg/kg. Pharmacokinetic studies of compounds 47c and 50b in rats highlighted their excellent oral bioavailabilities, indicating that they represent the first orally active non-peptide B2 antagonists reported to date.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 1: Hemodynamic effects in normal dogs and dogs with acute heart failure

Cardiovascular effects of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine), a calcium channel blocker, were investigated in anesthetized normal dogs and dogs with acute heart failure (AHF), and compared with those of nitroglycerin (NTG). In open-chest anesthetized dogs, NIC (0.1-10 micrograms/kg/min i.v.) dose-dependently increased cardiac output (CO) and coronary blood flow as well as decreased mean blood pressure (MBP). NIC had no effect on heart rate (HR) or maximum rate of rise of left ventricular pressure (max. dp/dt). In contrast (0.1-10 micrograms/kg/min i.v.) decreased MBP, but did not change the other cardiovascular parameters. NIC and NTG did not prolong PQ, QRS or QTc intervals. In addition, NIC was effective in the presence of dobutamine. In the anesthetized dog model of ischemic AHF induced by coronary ligation, and ischemia/angiotensin II-induced AHF, NIC (1 and 3 micrograms/kg/min i.v.) increased CO and stroke volume, and reduced total peripheral resistance without decreasing HR or cardiac contractility. Furthermore, in the ischemia/angiotension II-induced AHF model, NIC decreased left ventricular end-diastolic pressure (LVEDP). In contrast, NTG (1-10 micrograms/kg/min i.v.) decreased LVEDP in both AHF models; but did not increase CO. These results suggest that NIC improves hemodynamics in dogs with AHF mainly by reducing afterload without adversely affecting the cardiac contractility or conduction system, while NTG exerts its effect on AHF by reducing preload. NIC injection would thus appear to be beneficial in the treatment of AHF.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 2: Effect on myocardial metabolism

The effect of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine) on myocardial metabolism was investigated in an experimental model of ischemic acute heart failure (AHF) induced by coronary ligation in anesthetized dogs. The left anterior descending and/or circumflex coronary ligation decreased coronary sinus blood flow (CBF), maximum rate of rise of left ventricular pressure (max. dp/dt), cardiac output (CO) and stroke volume (SV), and increased left ventricular end-diastolic pressure, indicating the development of AHF. In this ischemic AHF model, NIC (3 micrograms/kg/min i.v. infusion for 15 min) increased CBF, CO and SV, and reduced systemic and coronary artery resistances, resulting in the improvement of AHF. During the effective period, NIC decreased myocardial oxygen consumption and the coronary arterio-venous difference of oxygen content, carbon dioxide pressure and pH. At the same time, NIC did not decrease the lactate extraction. These results suggest that NIC improves hemodynamics and the balance of myocardium oxygen supply and demand in dogs with AHF by means of reducing afterload and dilating coronary artery.

Neuropeptides in the livers of mice during bacterial infections

Neuropeptides such as substance P (SP) and vasoactive intestinal peptide (VIP) are known to act as immunomodulators. We investigated the induction of SP and VIP in the livers of mice infected with Listeria monocytogenes or injected with Tsukamurella paurometabolum. VIP was detected in the livers of mice after L. monocytogenes infection by an immunohistochemical technique and preproVIP mRNA, which was detected by reverse transcription-polymerase chain reaction (PCR), was induced post infection. However, no SP was detected. In contrast, SP, but not VIP was detected within granulomas in the livers of T. paurometabolum-injected mice, suggesting VIP and SP might be selectively induced in the liver by different bacterial infections.

Elevated plasma nitrate in patients with crush syndrome caused by the Kobe earthquake

We investigated the nitric oxide profile in the plasma of ten healthy controls and 29 patients hurt by the Kobe Earthquake. The levels of nitrite (NO2-) and nitrate (NO3-) were measured simultaneously by high-performance liquid chromatography (HPLC) with UV detection using the Griess reaction after the reduction of nitrate to nitrite. Arginine consumed in food or diet-derived nitrite had no effect on the plasma nitrite and nitrate contents of the healthy volunteers. Plasma nitrate was elevated in the crush syndrome patients; whereas neither nitrite nor nitrate was increased in patients with normal renal function. This finding suggests increased nitric oxide synthesis, decreased excretion of nitric oxide in the crush syndrome or both.

GTP-binding protein gamma12 subunit phosphorylation by protein kinase C--identification of the phosphorylation site and factors involved in cultured cells and rat tissues in vivo

We have demonstrated previously that the GTP-binding protein gamma12 subunit is a selective substrate for phosphorylation by protein kinase C among various gamma subunits in vitro, and that a serine residue in the N-terminal region is involved. In the present study, we first determined that the site of phosphorylation was Ser1 with antibodies developed against two N-terminal peptides containing phosphorylated Ser1 and Ser2, respectively. Using an antibody recognizing phosphorylated gamma12 and Swiss 3T3 cells rich in this protein, gamma12 was found to be phosphorylated by stimulation of quiescent cells with various reagents, such as phorbol 12-myristate 13-acetate (PMA), NaF, fetal calf serum, lysophosphatidic acid, endothelin, and growth factors. Pertussis toxin completely and partially prevented phosphorylation of gamma12 induced by lysophosphatidic acid and fetal calf serum and by endothelin, respectively, suggesting a contribution of G(i/o). Phosphorylation of gamma12 was limited when cells were stimulated by a single reagent, even with PMA, a strong activator of protein kinase C, whereas simultaneous stimulation with lysophosphatidic acid and either PMA or platelet-derived growth factor induced a synergistic increase of phosphorylation, suggesting physiological roles for GTP-binding proteins and protein kinase C in combination. Phosphorylated gamma12 was also detected in various tissues of untreated rats. Its decrease by pertussis toxin treatment also suggested the involvement of G(i/o) in vivo.

Effects of a nonpeptide bradykinin B2 receptor antagonist, FR167344, on different in vivo animal models of inflammation

1. The effects of a novel, potent and orally active nonpeptide bradykinin B2 receptor antagonist, FR167344 (N-[N-[3-[(3-bromo-2-methylimidazo[1,2-a]pyridin-8-yl)oxymethyl]-2 ,4-dichlorophenyl]-N-methylaminocarbonylmethyl]-4-(dimethylamin ocarbonyl) cinnamylamide hydrochloride) were tested in three different in vivo models of inflammation. 2. Oral administration of FR167344 inhibited carrageenin-induced paw oedema in rats (carrageenin: 1%, 0.1 ml per animal, intraplantar), with an ID50 of 2.7 mg kg(-1) at 2 h after carrageenin injection (n=10 or 11). 3. Oral administration of the compound also inhibited kaolin-induced writhing (kaolin: 250 mg kg(-1), i.p.) in mice, with ID50 of 2.8 mg kg(-1) in 10 min writhing and 4.2 mg kg(-1) in 15 min writhing (n=19 or 20). 4. Additionally, oral administration of FR167344 inhibited caerulein-induced pancreatic oedema with an ID50 of 13.8 mg kg(-1) as well as increases in amylase and lipase of blood samples with ID50 of 10.3 and 7.4 mg kg(-1), respectively, in rats (n=10). 5. These results show that FR167344 is an orally active, anti-inflammatory and anti-nociceptive agent in carrageenin-induced paw oedema, kaolin-induced writhing and caerulein-induced pancreatitis. FR167344 may have therapeutic potential against inflammatory diseases by oral administration and it may be a useful tool for studying the involvement of B2 receptors in various in vivo models of inflammation.

Omega-3 polyunsaturated fatty acids inhibit migration of human vascular smooth muscle cells in vitro

Arterial smooth muscle cell migration from the media to the intima is a crucial process in the pathogenesis of atherosclerosis. Platelet-derived growth factor (PDGF) has been proposed to play a key role in the development of advanced atherosclerotic lesions by stimulating the migration and proliferation of vascular smooth muscle cells. Polyunsaturated fatty acids (PUFA) of the omega-3 series, extracted from fish oil has been shown to have beneficial effects on atherosclerosis. In this study, we evaluated the effects of omega-3 PUFA on the migration of human aortic smooth muscle cell (hASMC) in vitro. The migration assay was performed according to the Capsoni's method using transwell culture plates. PDGF, fibrinogen or 10% FCS significantly stimulated hASMC migration, however, omega-3 PUFA significantly inhibited PDGF-induced migration of hASMC. These results suggest that the inhibitory effect of omega-3 PUFA on cell migration may be an important aspect by which omega-3 PUFA exerts its antiatherosclerotic influence.

Epicoprostanol found in adipocere from five human autopsies

Adipocere formation is well known as a later postmortem change. We collected adipocere from five male victims which had been submerged under the sea or fresh water for 1 mon to 4 yr. Fresh subcutaneous fat of a male victim who died from a cerebral contusion was used as the control. The samples were homogenized, and the lipids were extracted with chloroform and methanol followed by injection into a gas chromatograph and a gas chromatograph-mass spectrometer. We detected hydroxy fatty acids (10-hydroxyoctadecanoic acid and 10-hydroxyhexadecanoic acid) as well as 10-ketooctadecanoic acid in adipocere, but not in the control. In addition, we found for the first time a cholesterol-related peak with a molecular ion of 388 in adipocere and identified it as epicoprostanol, suggesting not only oxidation but also reduction had occurred during the formation of adipocere. In addition, we showed the time-course of epicoprostanol accumulation. The relationship between the time of adipocere formation and the characteristic lipid composition is discussed.

Antianginal effects of YM430, a novel calcium entry-blocking and beta-adrenoceptor-blocking agent in several experimental angina models

1. We evaluated the antianginal effects of YM430 in several experimental models in vitro and in vivo. 2. In isolated dog coronary artery, YM430 (10(-8)-10(-6) M) inhibited 3,4-diaminopyridine-induced rhythmic contractions with an IC50 value of 59.2 nM. 3. In anesthetized rats, YM430 (10-100 mg/kg PO) inhibited arginine vasopressin-induced ST-segment depression with an IC50 value of 36.6 mg/kg PO. 4. In anesthetized dogs, YM430 (0.3 mg/kg IV) significantly inhibited ST-segment elevation induced by coronary artery occlusion. 5. These findings suggest that YM430 may be of value in the treatment of various types of angina pectoris such as variant and stable angina.

The polymeric immunoglobulin receptor (secretory component) in a human intestinal epithelial cell line is up-regulated by interleukin-1

Secretory component (SC or polymeric immunoglobulin receptor) on mucosal epithelial cells mediates transcytosis of polymeric immunoglobulin into external fluids and functions as a receptor for polymeric immunoglobulin. SC expression in a human colonic adenocarcinoma cell line, HT-29 has been reported to be up-regulated by various cytokines, such as interferon-gamma, tumour necrosis factor-alpha and interleukin-4 (IL-4). However, up-regulation of SC by IL-1 is controversial. In this study, we investigated the effect of human recombinant IL-1 alone on SC expression in HT-29 cells in detail. Immunocytochemistry and Northern blot analysis revealed that IL-1 beta increased both the number of SC-positive cells and SC mRNA expression. Enzyme-linked immunosorbent assay revealed that IL-1 beta enhanced secretion by HT-29 cells in both time- and dose-dependent manners. IL-1 alpha had the same effects on HT-29 cells. Northern blot analysis demonstrated that cycloheximide and actinomycin D abolished the effect of IL-1. Moreover, we detected IL-1 receptor (IL-1R) type I mRNA in HT-29 cells by polymerase chain reaction (PCR) and sequenced the PCR-amplified product. We think that it reflects the possibility of the presence of IL-1R in HT-29 cells. From these data, we concluded that IL-1 beta and IL-1 alpha play regulatory roles in SC expression, and their effects depend on de novo protein synthesis and transcription.

Molecular cloning and characterization of the promoter of the human N-methylpurine-DNA glycosylase (MPG) gene

The promoter region of the human N-methylpurine-DNA glycosylase (MPG) gene was cloned and characterized. The cloned segment contains two first exons that were earlier identified and named exons 1a and 1b. These were found to be separated by approximately 800 bp. The minimal promoter region was identified upstream to the distal exon 1a, by transient transfection, and no promoter activity was found in the region in between exons 1a and 1b, suggesting that transcription starts at a single site which is then processed to generate mRNAs of the isoforms. The promoter sequence is G and C rich and contains neither TATA box, nor apparent CAAT sequences, although a partially matched CAAT sequence was identified just downstream to the minimal promoter.

Pharmacological characterization of a novel, orally active, nonpeptide bradykinin B2 receptor antagonist, FR167344

To investigate the pathophysiological role of bradykinin and to develop a drug for inflammatory diseases, we discovered an orally active, nonpeptide bradykinin B2 receptor antagonist, FR167344, N-[N-[3-[(3-bromo-2-methylimidazo[1,2-a]pyridin-8-yl)oxymethyl]-2, 4dichlorophenyl]-N-methylaminocarbonylmethyl]-4-(dimethyl aminocarbonyl) cinnamylamide hydrochloride. This compound competitively displaced [3H]bradykinin binding to bradykinin B2 receptors present in guinea-pig ileum membrane with an IC50 value of 6.6 X 10(-10) M. In isolated guinea-pig ileum preparations, it also antagonized bradykinin-induced contraction with a pA2 value of 9.3. In human lung fibroblast IMR-90 cells, FR167344 displaced [3H]bradykinin binding to human bradykinin B2 receptors with an IC50 value of 1.3 X 10(-8) M, but not [3H]des-Arg10-kallidin binding to human bradykinin B1 receptors. In vivo, oral administration of FR167344 inhibited bradykinin-induced bronchoconstriction in guinea pigs and the bradykinin-induced hypotensive response for 6 h in rats. These results show that FR167344 is a potent, selective, orally active and long acting bradykinin B2 receptor antagonist.

Nonpeptide mimic of bradykinin with long-acting properties at the bradykinin B2 receptor

Kinins, members of a family of peptides released from kininogens by the action of kallikreins, exhibit a variety of biological activities including vasodilation, increased vascular permeability, contraction of smooth muscle cells, and activation of sensory neurons. However, investigation of the physiological actions of kinins has been greatly hampered because its effects are curtailed by rapid proteolysis in blood, lung, and liver. We describe the pharmacological characteristics of a novel nonpeptide bradykinin receptor agonist FR190997 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacetyl ]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoli ne). FR190997 markedly stimulated phosphatidylinositol hydrolysis in Chinese hamster ovary cells permanently expressing the human bradykinin B2 receptor. The response of phosphatidylinositol hydrolysis was antagonized by the B2 receptor selective antagonist Hoe 140 (D-Arg-[hydroxyproline3,beta-thienylalanine4,D-Tic7,++ +Oic8]bradykinin). In competitive experiments using membranes prepared from Chinese hamster ovary cells expressing the human bradykinin receptor subtypes, FR190997 showed a high affinity binding to the B2 receptor with IC50 value of 5.3 nM and no binding affinity for the B1 receptor. In vivo, FR190997 mimics the biological action of bradykinin and induces hypotensive responses in rats with prolonged duration. Therefore, FR190997 is a highly potent and subtype-selective nonpeptide agonist which displays high intrinsic activity. This compound should represent a powerful tool for further investigation of the physiology and pathophysiology of bradykinin receptors.

Macrophage antigen-1 positive cells are essential in the defense against Theiler's virus strain GD VII infection in the spinal cord

Acute encephalomyelitis caused by Theiler's virus strain GD VII resembles human poliomyelitis, and T cells are essential in eliminating the virus from the brain, though not from the spinal cord. We speculated that macrophage-lineage cells might play a crucial role in eliminating the virus from the spinal cord. To analyse the role of macrophage-lineage cells in the infection, antibodies specific for beta2 integrin, as well as an anti-leukocyte function antigen 1 (LFA-1) monoclonal antibody (MAb) and an anti-complement receptor type 3 (CR3) MAb were used to deplete the corresponding cell populations in Theiler's virus-infected mice. Infiltration of CD8+ T cells into the brain and spinal cord was inhibited by the administration of the anti-LFA-1 MAb, and viral replication was augmented only in the brain. The number of CD4+ T cells and macrophage antigen-1 (Mac-1[+]) cells in the brain and spinal cord were not decreased by anti-LFA-1 MAb treatment. Anti-CR3 MAb treatment led to decrease of Mac-1(+) cells in the brain and spinal cord. The viral replication in the spinal cord of anti-CR3 MAb treated mice was augmented, but not that in the brain. These results indicate that the defense mechanism against Theiler's virus strain GD VII is dependent on Mac-1(+) cells in the spinal cord.

Characterization of FR173657, a novel nonpeptide B2 antagonist: in vitro and in vivo studies

Bradykinin (BK) is involved in different pathophysiological conditions, including allergic and (or) inflammatory reactions. Thus, BK antagonists are considered as a potential drug in allergic and (or) inflammatory diseases. Orally active BK antagonist would be desirable for this purpose. Here, we describe the pharmacological characterization of FR173657 ((E)-3-(6-acetamido-3-pyridyl)-N-[N-[2,4-dichloro-3-[(2-methyl-8- quinolinyl)oxymethyl]phenyl]-N-methylaminocarbonylmethyl]acr ylamide) obtained from our screening for nonpeptide, orally active B2 antagonists. (i) FR173657 antagonized [3H]BK binding with IC50 values of 4.6 x 10(-10) and 8.6 x 10(-9) M in membrane preparations of guinea pig ileum and lung, respectively. FR173657 inhibited [3H]BK binding to A431, W138, and IMR90 cell lines of human origin with IC50 values of 2.0 x 10(-9), 2.3 x 10(-9), and 1.7 x 10(-9) M, respectively. FR173657 did not affect [3H]des-Arg10-kallidin (B1 ligand) binding onto IMR90 cells. (ii) FR173657 inhibited guinea pig ileum contractions by BK (6 x 10(-8) M) with an IC50 value of 6.1 x 10(-9) M. Acetylcholine- and histamine-induced contraction of guinea pig ileum was unaffected by FR173657. (iii) Oral administration of FR173657 dose-dependently inhibited BK (5 micrograms/kg) and dextran sulfate (activator of kinin-kallikrein cascade) induced bronchoconstriction with ED50 values of 0.075 and 0.057 mg/kg, respectively. In conclusion, FR173657 is a selective potent, orally active B2 receptor antagonist that can be used to investigate the role of BK in allergic and inflammatory diseases.

Clinical, pathological, and etiologic aspects of acquired dermal melanocytosis

To study the pathogenesis of acquired dermal melanocytosis (ADM), we reviewed the clinical, immunohistochemical, and ultrastructural features of 34 cases (female, 33, and male, 1) of ADM. The patients' ages at onset ranged from 8 to 51 years and averaged 26.8 +/- 12.7 years. There was a positive family history. Gray-brown macules were mostly recognized on the face. Not only active dermal melanocytes but also non-pigmented c-KIT- and TRP-2-positive immature melanocytes were detected in the dermis. Taken together those clinical and histological findings, activation of pre-existing immature melanocytes by sunlight, estrogen, and/or progesterone, and some other factors, may be the most likely mode of the development of ADM. Moreover, using cultured murine neural crest cells as a model of c-KIT-positive immature melanocytes, we confirmed that endothelin-1, which is produced and secreted by keratinocytes after UV-irradiation, affects melanocytes and accelerated melanogenesis.

Cloning and characterization of mammalian 8-hydroxyguanine-specific DNA glycosylase/apurinic, apyrimidinic lyase, a functional mutM homologue

8-Hydroxyguanine (8-OH-G) is one of the major DNA oxidation products implicated in mutagenesis induced by oxygen radical-forming agents, including ionizing radiation. It is also believed to be involved in spontaneous mutation induced by metabolically produced oxygen radicals. A mammalian homologue of 8-OH-G glycosylase/apurinic, apyrimidinic lyase (mutM homologue, MMH) has been identified in the EST database (for expressed sequence tags) through a homology search with yeast OGG1 protein. The human MMH protein (hMMH), 34% identical to the yeast OGG1 protein, is a member of the DNA repair protein superfamily. The hMMH gene was composed of seven exons, with the alternate last exon, exon 8, producing three major alternative splicing isoforms, because splicing of the sixth intron was optional. The hMMH protein expressed in Escherichia coli revealed the glycosylase activity and apurinic, apyrimidinic lyase activity on duplex DNA containing 8-OH-G. The hMMH protein can rescue a spontaneous mutator strain of E. coli lacking mutM and mutY. By the introduction of recombinant hMMH, the rate of mutation, the formation of rifampicin-resistant revertants, was reduced by 4-7 fold. Genomic structure analysis showed that 3' exons of the hMMH gene are transcribed on the antisense strand of the calcium-dependent calmodulin kinase 1 gene.

Acute effects of thromboxane dual blocker (KDI-792) on different portions of lower limb blood flow--a study using Doppler ultrasonography and laser Doppler flowmetry in type 2 diabetic patients

The acute effects of a newly synthesized thromboxane dual blocker (KDI-792), a combined thromboxane synthase inhibitor and receptor antagonist, on lower limb circulation were examined using two-dimensional color and pulse Doppler ultrasonography and laser Doppler flowmetry. A randomized single-masked, placebo-controlled trial was performed on 36 type 2 diabetic patients with minimally impaired baseline flow. The anatomical cross-sectional area (CSA), maximum flow velocity (MFV) and flow volume index (FVI) in the right dorsal pedis artery (DPA) and right femoral artery (FA) were determined by Doppler ultrasonography before and 45 and 90 minutes after the administration of either 100 or 200 mg of KDI-792 to the dose groups or placebo to the control group. Periflux blood flow (PBF) in the right foot was determined simultaneously by laser Doppler flowmetry. Both CSA and MFV in the dose groups were significantly increased in both the FA and DPA. FVI was markedly increased from 21.4 +/- 3.7 to 68.3 +/- 26.8 in the DPA (M +/- SD, P < 0.01) and from 365.4 +/- 35.3 to 771.7 +/- 75.7 in the FA (P < 0.01) in the 200 mg dose group. In the 100 mg dose group, FVI was markedly increased from 20.0 +/- 8.7 to 68.3 +/- 26.8 (P < 0.01) in the DPA and from 372.5 +/- 130.0 to 677.5 +/- 187.8 (P < 0.01) in the FA. PBF was also increased in both dose groups (from 4.15 +/- 1.4 to 7.0 +/- 4.0 ml/min/100 g tissue in the 200 mg dose group, P < 0.01), whereas there were no significant changes in either measurement in the control group. There were no significant changes in pulse rate or blood pressure after administration in either the dosage group or the placebo group. These and previous findings indicate that a single administration of KDI-792 markedly increases lower limb blood flow and might have a more potent vasodilating effect than that of prostaglandin I2 derivatives.

Dementia in a diabetic man

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Characterization of 30-kDa fragments derived from beta-conglycinin degradation process during germination and seedling growth of soybean

The degradation process of beta-conglycinin, a vicilin-type glycosylated storage protein of soybean seeds, during germination and seedling growth was examined by concanavalin A blotting combined with polyacrylamide gel electrophoresis. We detected and analyzed the structures of key intermediary fragments of 30 kDa derived from beta-conglycinin degradation, they were proved to be single-domain type subunits of beta-conglycinin. We show here a degradation process of beta-conglycinin: beta-conglycinin is subjected to limited proteolysis at exposed regions on the molecular surface, like domain junctions, generating 30-kDa single-domain fragments before non-specific proteolysis.

Growth retardation and early death of beta-1,4-galactosyltransferase knockout mice with augmented proliferation and abnormal differentiation of epithelial cells

Carbohydrate chains on a glycoprotein are important not only for protein conformation, transport and stability, but also for cell-cell and cell-matrix interactions. UDP-Gal:N-acetylglucosamine beta-1,4-galactosyltransferase (GalT) (EC 2.4.1.38) is the enzyme which transfers galactose (Gal) to the terminal N-acetylglucosamine (GlcNAc) of complex-type N-glycans in the Golgi apparatus. In addition, it has also been suggested that this enzyme is involved directly in cell-cell interactions during fertilization and early embryogenesis through a subpopulation of this enzyme distributed on the cell surface. In this study, GalT-deficient mice were produced by gene targeting in order to examine the pathological effects of the deficiency. GalT-deficient mice were born normally and were fertile, but they exhibited growth retardation and semi-lethality. Epithelial cell proliferation of the skin and small intestine was enhanced, and cell differentiation in intestinal villi was abnormal. These observations suggest that GalT plays critical roles in the regulation of proliferation and differentiation of epithelial cells after birth, although this enzyme is dispensable during embryonic development.

Pulmonary blood flow regulates plasma tissue plasminogen activator concentrations in patients with congenital heart defects

OBJECTIVE

The wall shear stress generated by blood flow regulates the expression of fibrinolytic proteins by endothelial cells in vitro. In the present study, the effects of pulmonary blood flow on fibrinolytic activity were studied in patients with congenital heart defects and pulmonary hypertension.

METHODS

Twenty-seven patients who underwent cardiac operation because of congenital heart defects were divided into four groups according to the severity of pulmonary hypertension. Group I consisted of seven patients with normal pulmonary artery pressure, group II consisted of nine patients with pulmonary hypertension caused by increased pulmonary blood flow, group III consisted of six patients with pulmonary hypertension caused by increased pulmonary vascular resistance, and group IV consisted of five patients with tetralogy of Fallot. Plasma concentrations of tissue plasminogen activator, plasmin, and thrombin were assayed as the inhibitor-bound forms.

RESULTS

The preoperative concentration of tissue plasminogen activator was higher in group II than in all other groups (p = 0.0003). However, the postoperative concentration decreased only in patients in group II when compared with the preoperative value (p = 0.01). By Pearson's correlation analysis, pulmonary blood flow was found to correlate with the preoperative concentration of tissue plasminogen activator (95% confidence interval = 3.99 to 10.58, p = 0.0001). No definite conclusion was found for the relationship between tissue plasminogen activator and plasmin concentration. Further, the preoperative thrombin concentration was similar in all groups.

CONCLUSIONS

These findings suggest that pulmonary blood flow may regulate the plasma concentration of tissue plasminogen activator in patients with congenital heart defects.

Studies on cardiac ingredients of plants. XIII: Chemical modification of gitoxin to cardiotonic compounds without vascular effect

Nitrated gitoxins (4) and bufotoxin homologues with various lengths of alkyl chain at C-3 of the steroid nucleus (10) were prepared from gitoxin (1). The pharmacological activities of the resulting compounds (4 and 10) were evaluated by measurement of inhibitory effect on NA+, K(+)-adenosine triphosphatase (ATPase) prepared from dog kidney, positive inotropic effect (PIE) on isolated guinea-pig papillary muscle preparations, and the effect on smooth muscle using the mesenteric artery from spontaneously hypertensive rats. Most of the compounds showed a smaller contractile effect on the arterial muscle. Among these compounds, gitoxin 3"-nitrate (4g) exhibited the most desirable biological activities, such as PIE comparable to that of 1, 1.25 times wider concentration-dependent range than 1, and lack of contractile activity on vascular muscle.

Eicosapentaenoic acid enhances nitric oxide production by cultured human endothelial cells

It is unclear whether the abnormal relaxation seen in diabetes is due to decreased levels of nitric oxide (NO) and how eicosapentaenoic acid (EPA, C20:5 omega 3) affects the endothelial production of NO. We investigated the effects of EPA ethyl ester (EPA-E) and elevated glucose on NO production by human endothelial cells (HUE). EPA-E (0.3 mM) significantly enhanced [NO2] production and the intracellular concentration of free Ca2+ within 3 min after EPA-E was added to the cultures. High levels of glucose (27.5 mM) significantly increased endothelial glucose, sorbitol and fructose, and inhibited [NO2-] production. However, EPA-E (0.3 mM) prevented the inhibition of [NO2-] production due to the activation of the Ca(2+)-calmodulin system of NO synthase. EPA-E decreased the glucose-mediated inhibition of NO production by HUE. These results suggest this agent might ameliorate endothelial dysfunction associated with diabetes.

Renal effect of YM435, a new dopamine D1 receptor agonist, in anesthetized dogs

The renal effects of YM435 ((-)-(S)-4-(3,4-dihydroxyphenyl)-7,8-dihydroxy -1,2,3,4-tetrahydroisoquinoline hydrochloride hydrate), a dopamine D1 receptor agonist, were investigated in anesthetized dogs. Intravenous infusion of YM435 (0.1-3 micrograms/kg per min) increased renal blood flow and decreased mean blood pressure in a dose-dependent manner with little effect on heart rate. Glomerular filtration rate, urine flow and urinary sodium excretion were concomitantly increased. The renal effect of YM435 by intravenous infusion at 0.3 microgram/kg per min was completely blocked by treatment with the selective dopamine D1 receptor antagonist SCH 23390 (7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazep ine hydrochloride). Furthermore, intravenous infusion of YM435 (0.3 microgram/kg per min) reversed the angiotensin II-induced decreases in renal blood flow, glomerular filtration rate, urine flow and urinary sodium excretion, and prevented the decrease in renal blood flow, glomerular filtration rate and urine flow induced by renal nerve stimulation and platelet-activating factor (PAF). These results suggest that intravenous administration of YM435 produces renal vasodilating and diuretic/natriuretic effects by stimulation of dopamine D1 receptors, and demonstrate that YM435 can inhibit angiotensin II-, renal nerve stimulation- and PAF-induced renal dysfunction.

Cardiovascular effects of YM430, a 1,4-dihydropyridine derivative with beta-adrenoceptor blocking activity, in dogs and rats

We evaluated the cardiovascular effects of YM430, a novel 1,4-dihydropyridine derivative with beta-adrenoceptor blocking activity, in dogs and rats. In anesthetized dogs, YM430 (0.01-0.3 mg/kg, i.v.) dose-dependently decreased mean blood pressure, total peripheral resistance and double product without increasing the heart rate. YM430 (0.01-0.3 mg/kg, i.v.) increased coronary artery as well as vertebral artery blood flow, whereas its effects on carotid, mesenteric, femoral and renal blood flow were small. At the same dose range as that which induced vasodilation effects, YM430 had little effect on the max. dp/dt or PQ-interval. In conscious dogs, YM430 (0.1-1 mg/kg, i.v.) produced dose-dependent hypotension with tachycardia. In conscious rats, oral dosing of YM430 (100 mg/kg p.o.) produced a long-lasting hypotensive effect with slight tachycardia. YM430 also inhibited isoproterenol (0.1 micrograms/kg i.v.)-induced tachycardia. These two effects of YM430 may be attributable to its calcium entry blocking and beta(1)-adrenoceptor blocking activity, respectively. The time course of the hypotensive (calcium entry blocking) effect of YM430 after oral dosing was very similar to that of its inhibition of isoproterenol-induced tachycardia (beta(1)-adrenoceptor blocking effect). These results indicate that the ratio of the two activities (calcium entry blocking and beta(1)-adrenoceptor blocking) of YM430 is constant after oral administration. In conclusion, YM430 could be both an antianginal and antihypertensive agent, because of its dual activities.

Hemodynamic characterization of YM435, a novel dopamine DA1 receptor agonist, in anesthetized dogs

The cardiovascular effects of YM435, a dopamine DA1 receptor agonist, were compared with those of dopamine in open-chest anesthetized dogs. Intravenous infusion of YM435 (0.1-3 microg/kg/min) increased renal blood flow and cardiac output and reduced renal vascular resistance and total peripheral vascular resistance, with a decrease in mean blood pressure, in a dose-dependent manner, with little change in heart rate. At 1 microg/kg/min i.v., renal blood flow increased by 20 +/- 7%, cardiac output increased by 14 +/- 6%, renal vascular resistance decreased by 22 +/- 4%, total peripheral vascular resistance decreased by 18 +/- 4%, and mean blood pressure decreased by 7 +/- 1%. The striking difference between the cardiovascular effects of YM435 and those of dopamine was that YM435 caused no vasoconstriction or increase in heart rate, even at high doses. The cardiovascular effects of YM435 (1 microg/kg/min i.v.) were almost completely inhibited by treatment with SCH 23390, a selective dopamine DA1 receptor antagonist. Furthermore, intravenous infusion of YM435 (0.1-3 microg/kg/min) dose-dependently reversed the increase in blood pressure and renal vascular resistance induced by angiotensin II or norepinephrine in closed-chest anesthetized dogs. Our results demonstrate that intravenous infusion of YM435 produces dose-dependent renal vasodilating and hypotensive effects by stimulation of dopamine DA1 receptors and suggest that YM435 may be useful for the parenteral treatment of acute elevation of blood pressure.

Inhibitory effects of omega-3 polyunsaturated fatty acids on receptor-mediated non-selective cation currents in rat A7r5 vascular smooth muscle cells

1. The effects of omega-3 polyunsaturated fatty acids on receptor-mediated non-selective cation current (Icat) and K+ current were investigated in aortic smooth muscle cells from foetal rat aorta (A7r5 cells). The whole-cell voltage clamp technique was employed. 2. With a K(+)-containing solution, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA, 30 microM) produced an outward current at a holding potential of -40 mV. This response was inhibited by tetraethylammonium (20 mM) or Cs+ in the patch pipette solution, and the reversal potential of the EPA-induced current followed the K+ equilibrium potential in a near Nernstian manner. 3. Under conditions with a Cs(+)-containing pipette solution, both vasopressin and endothelin-1 (100 nM) induced a long-lasting inward current at a holding potential of -60 mV. The reversal potential of these agonist-induced currents was about +0 mV, and was not significantly altered by the replacement of the extracellular or intracellular Cl+ concentration, suggesting that the induced current was a cation-selective current (Icat). 4. La3+ and Cd2+ (1 mM) completely abolished these agonist-induced Icat, but nifedipine (10 microM) failed to inhibit it significantly. 5. omega-3 polyunsaturated fatty acids (3-100 microM), EPA, DHA and docosapentaenoic acids (DPA), inhibited the agonist-induced Icat in a concentration-dependent manner. The potency of the inhibitory effect was EPA > DHA > DPA, and the half maximal inhibitory concentration (IC50) of EPA was about 7 microM. 6. Arachidonic and linoleic acids (10, 30 microM) showed a smaller inhibitory effect compared to omega-3 fatty acids. Also, oleic and stearic acids (30 microM) did not show a significant inhibitory effect on Icat. 7. A similar inhibitory action of EPA was observed when Icat was activated by intracellularly applied GTP gamma S in the absence of agonists, suggesting that the site of action of omega-3 fatty acids is not located on the receptor. 8. These results demonstrate that omega-3 polyunsaturated fatty acids can activate a K+ current and also effectively inhibit receptor-mediated non-selective cation currents in rat A7r5 vascular smooth muscle cells. Thus, the data suggest that omega-3 fatty acids may play an important role in the regulation of vascular tone.