Antagonism of peptidoleukotrienes and inhibition of systemic anaphylaxis by RG 12525 in guinea pigs

RG 12525 was determined to be a specific, competitive and orally effective antagonist of the peptidoleukotrienes, LTC4, LTD4 and LTE4, in several assays utilizing guinea pigs. In vitro, RG 12525 competitively inhibited 3H-LTD4 binding to lung membranes (Ki = 3.0 +/- 0.3 nM) and competitively antagonized the spasmogenic activity of LTC4, LTD4 and LTE4 on lung strips (KB values = 3 nM) with greater than 8000 fold selectivity. In vivo, RG 12525 orally inhibited LTD4 induced wheal formation (ED50 = 5 mg/kg with a t1/2 = 10 hrs at 9 mg/kg), LTD4 induced bronchoconstriction (ED50 = 0.6 mg/kg), and anaphylactic death (ED50 = 2.2 mg/kg with a t1/2 = 7 hrs at 10 mg/kg) and antigen induced bronchoconstriction (ED50 = 0.6 mg/kg). RG 12525 represents a significant improvement in receptor affinity and oral efficacy and thus, is a valuable pharmacological tool to evaluate peptidoleukotrienes in allergic diseases.     

The human renin infused rat: use as an in vivo model for the biological evaluation of human renin inhibitors

The human renin infused rat model (HRIRM) was used as an in vivo small-animal model for evaluating the efficacy of a collection of inhibitors of human renin. The intravenous infusion of recombinant human renin (2.4 microg x kg(-1) x min(-1)) in the ganglion-blocked, nephrectomized rat produced a mean blood pressor response of 47+/-3 mm Hg (1 mm Hg = 133.3 Pa), which was reduced by captopril, enalkiren, and losartan in a dose-dependent manner following oral administration, with ED50 values of 0.3+/-0.1, 2.5+/-0.9, and 5.2+/-1.6 mg/kg, respectively. A series of peptidomimetic P2-P3 butanediamide renin inhibitors inhibited purified recombinant human renin in vitro in a concentration-dependent manner, with IC50 values ranging from 0.4 to 20 nM at pH 6.0, with a higher range of IC50 values (0.8-80 nM) observed at pH 7.4. Following i.v. administration of renin inhibitors, the pressor response to infused human renin in the HRIRM was inhibited in a dose-dependent manner, with ED50 values ranging from 4 to 600 microg/kg. The in vivo inhibition of human renin following i.v. administration in the rat correlated significantly better with the in vitro inhibition of human renin at pH 7.4 (r = 0.8) compared with pH 6.0 (r = 0.5). Oral administration of renin inhibitors also resulted in a dose-dependent inhibition of the pressor response to infused human renin, with ED50 values ranging from 0.4 to 6.0 mg/kg and the identification of six renin inhibitors with an oral potency of <1 mg/kg. The ED50 of renin inhibitors for inhibition of angiotensin I formation in vivo was highly correlated (r = 0.9) with the ED50 for inhibition of the pressor response. These results demonstrate the high potency, dose dependence, and availability following oral administration of the butanediamide series of renin inhibitors.     

Therapeutic evaluation of free and liposome-encapsulated atovaquone in the treatment of murine leishmaniasis

The use of drug delivery systems may reduce the toxicity and improve the activity of anti-leishmanial compounds. The activity of atovaquone (ATV)-loaded liposomes was compared by determination of median effective doses (ED(25) and ED(50)), with that of free ATV in a murine model of visceral leishmaniasis induced by Leishmania infantum. On day 0, mice were infected intravenously with 4.10(7) promastigotes and treated via the tail vein on days 15, 17 and 19 by free drug in a DMSO/cremophor/water solution (0.2 to 1.6 mg/kg body weight) or by liposomal drug (0.04 to 0.32 mg/kg body weight). Mice were killed and livers and spleens were removed and weighed on day 21 p.i. and liver parasite burdens evaluated using the Stauber method. Effective doses were determined using the Hill representation relating the percentage of parasite suppression to the dose. Liposomal ATV was significantly more effective than the free drug in reducing liver parasites (61.6% of parasite suppression at a dose of 0.32 mg/kg vs 34.9% at a dose of 1.6mg/kg). Liposomal ATV was 23 times more active than the free drug (ED(25) value=0. 02+/-0.01 mg/kg vs 0.46+/-0.15 mg/kg for free drug). It was not possible to obtain the ED(50) for free ATV because the dose-response curve reached a plateau around 33% of parasite suppression. Conversely, the ED(50) for liposomal ATV was 0.17+/-0.05 mg/kg. 100% efficacy of bound ATV could be obtained with a concentration of 1. 77+/-0.35 mg/kg. A significant decrease in spleen weights was also observed reflecting a leishmanicidal activity of ATV. These results suggest that liposome loaded ATV is more efficacious than the free drug against Leishmania infantum in this murine model.     

Diazen-1-ium-1,2-diolated nitric oxide donor ester prodrugs of 5-(4-hydroxymethylphenyl)-1-(4-aminosulfonylphenyl)-3-trifluoromethyl-1H-pyrazole and its methanesulfonyl analog: synthesis, biological evaluation and nitric oxide release studies

A new class of hybrid nitric oxide-releasing anti-inflammatory (AI) ester prodrugs (NONO-coxibs 12a-b) wherein an O(2)-acetoxymethyl 1-(2-carboxypyrrolidin-1-yl)diazen-1-ium-1,2-diolate (11, O(2)-acetoxymethyl PROLI/NO) NO-donor moiety was covalently coupled to the bromomethyl group of 5-(4-bromomethylphenyl)-1-(4-aminosulfonylphenyl)-3-trifluoromethyl-1H-pyrazole (9a), and its methanesulfonyl analog (9b), were synthesized. The diazen-1-ium-1,2-diolate compounds 12a-b released a low amount of NO upon incubation with phosphate buffer (PBS) at pH 7.4 (6.1-8.2% range). In comparison, the percentage NO released was significantly higher (76-77% of the theoretical maximal release of two molecules of NO/molecule of the parent hybrid ester prodrug) when the diazen-1-ium-1,2-diolate ester prodrugs 12a-b were incubated in the presence of rat serum. These incubation studies suggest that both NO and the anti-inflammatory 5-(4-hydroxymethylphenyl)-1-(4-aminosulfonylphenyl)-3-trifluoromethyl-1H-pyrazole (10a), and its methanesulfonyl analog (10b), would be released from the parent NONO-coxib 12a or 12b upon in vivo cleavage by non-specific serum esterases. The hydroxymethyl compounds 10a-b were weak inhibitors of the cyclooxygenase-1 (COX-1) and COX-2 isozymes (IC(50)=3.7-10.5 microM range). However, the hydroxymethyl compounds 10a-b and the parent NONO-coxibs 12a-b exhibited good AI activities (ED(50)=76.7-111.6 micromol/kg po range) that were greater than that exhibited by the reference drugs aspirin (ED(50)=710 micromol/kg po) and ibuprofen (ED(50)=327 micromol/kg po), but less than that of celecoxib (ED(50)=30.9mumol/kg po). These studies indicate hybrid ester AI/NO-donor prodrugs (NONO-coxibs) constitutes a plausible drug design concept targeted toward the development of selective COX-2 inhibitory AI drugs that are devoid of adverse cardiovascular effects.     

The involvement of intracellular calcium ion concentration and calmodulin in the 25-hydroxylation of cholecalciferol in ovine and rat liver

The effect of Ca2+ ion concentration on the 25 hydroxylation of tritiated cholecalciferol (3HD3) was investigated using homogenates of ovine liver from vitamin D replete sheep. A significant decrease in the production of 25 hydroxycholecalciferol (25OHD3) was observed when the concentration of Ca2+ in the homogenate was raised above 0.68 mmol/l by the addition of calcium gluconate. Similarly, a final concentration of 37 mumol EGTA/1 (equivalent to a Ca2+ concentration of 26.5 nmol/l) was associated with a 50% reduction of 25OHD3 production. That is, a broad bell-shaped relationship was observed between the production of 25OHD3 and the Ca2+ concentration in the homogenate. These changes in the rate of production of 25OHD3 were reproduced with hepatocytes from vitamin D replete rats, prepared by collagenase perfusion, using the drugs dantrolene sodium (DaNa) to reduce (ED50 = 57 mmol/l) and veratridine to increase (ED50 = 550 mmol/l) the intracellular Ca2+ concentration. Hepatocytes from vitamin D replete rats also showed a reduction in 25 hydroxylation of D3 (ED50 = 6 ng/ml) in response to the addition of 1-25 dihydroxycholecalciferol (1-25 (OH)2D3). The calmodulin antagonists; W7, compound 48/80, trifluoperazine (TFP) and calmidazolium (R24571) were all found to effect a dose response inhibition of the 25 hydroxylation of cholecalciferol by homogenates of ovine liver. R24571 had a similar inhibitory effect (ED50 = 70 mumol/l) upon the 25 hydroxylase enzyme of rat hepatocytes. It is concluded that the 25 hydroxylation of cholecalciferol in liver of vitamin D replete rats and sheep is calcium sensitive and is reduced in the presence of increased concentrations of 1,25(OH)2D3. Calmodulin may also be involved in the regulation of hepatocyte 25-hydroxylase activity by Ca2+.     

Interaction of antidepressants with 4-aminopyridine.

Systemic administration of 4-Aminopyridine at a dose of 4 mg/kg (4-AP) induces hypothermia in mice. Scopolamine (ED50 = 0.26 mg/kg) and two tricyclic antidepressants, desipramine (ED50 = 1.82 mg/kg) and IM/P/3/4 (ED50 = 8.95 mg/kg) completely antagonize 4-AP-induced hypothermia, whereas minaprine (0.1-0.25 mg/kg), a non-tricyclic antidepressant, reverts only 45% of the maximal effect of 4-AP. Oxotremorine at a dose of 0.05 mg/kg (OXO) induces a hypothermic effect comparable to that of 4-AP. Scopolamine (ED50 = 0.011 mg/kg) completely reverts OXO-induced hypothermia whereas desipramine and IM/P/3/4 never produce more than 60% of antagonism over a wide range of doses. Minaprine does not affect OXO-induced hypothermia. These results suggest that the interaction of antidepressants with cholinergic function occurs mainly at the pre-synaptic level.     

硫化氢对离体豚鼠乳头状肌的电生理效应

应用细胞内微电极技术,观察硫化氢（hydrogen sulfide,H2S）对离体豚鼠乳头状肌细胞的电生理效应。结果表明：（1）NaHS （H,S的供体,50、100、200μmol/L）可浓度依赖地缩短正常乳头状肌的动作电位时程。（2）对部分去极化乳头状肌,NaHS （100μmol／L）除缩短动作电位时程外,还降低动作电位幅值和超射值,减慢零相最大上升速度。（3）预先应用ATP敏感性钾（ATP- sensitive K＋,KATP）通道阻断剂格列苯脲（glibenclamide,Gli,20μmol／L）,可部分阻断NaHS（100μmol／L）的电生理效应。（4）预先应用L型钙通道开放剂Bay K8644（0．5μmol／L）,可部分阻断NaHS（100μmol／L）的电生理效应。（5）预先应用含Gli（20μmol／L）的无钙Krebs-Henseleit液灌流标本,可完全阻断NaHS（100μmol／L）的电生理效应。（6）DL-propargylglycine（PPG,一种胱硫醚-γ-裂解酶的不可逆抑制剂,200μmol／L）可延长正常乳头状肌的动作电位时程。以上结果提示,H,S可能通过兴奋KATP通道促进K＋外流,同时抑制Ca2＋内流,进而影响豚鼠乳头状肌电生理效应。乳头状肌中内源性H2S可能发挥重要的电生理作用。     

The anticonvulsant activities of N-benzyl 3-methoxypropionamides

We recently reported that the ED50 value for (R,S)-2,3-dimethoxypropionamide (1) in the maximal electroshock (MES)-induced seizure test in mice was 30 mg/kg (Choi, D.; Stables, J.P., Kohn, H. Bioorg. Med. Chem. 1996, 4, 2105). This value is comparable to that observed for phenobarbital (ED50 = 22 mg/kg). Compound 1 is structurally similar to a class of MES-selective anticonvulsant agents, termed functionalized amino acids (2), that were developed in our laboratory. The distinguishing feature of 2 is the differential activities observed for enantiomers. In this study, we asked whether comparable differences in activities were observed in the MES-induced seizure test for (R)- and (S)-1. We developed stereospecific syntheses for these enantiomers and showed that both compounds exhibit nearly equal anticonvulsant activity in mice (i.p.) (MES ED50 = 79-111 mg/kg). The surprisingly high ED50 values for (R)- and (S)-1 required our redetermining the ED50 value for (R,S)-1. We revised this value to 79 mg/kg. A limited structure-activity relationship study for 1 was conducted. Special attention was given to the C(2) methoxy unit in 1. We found that replacement of this moiety led to only modest differences in the MES activities upon ip administration to mice. Significantly, we observed an enhancement in the anticonvulsant activity for (R,S)-N-benzyl 2-hydroxy-3-methoxypropionamide ((R,S)-6) upon oral administration to rats ((R,S)-6: mice (i.p.) ED50 > 100, < 300 mg/kg; rat (oral) ED50 = 62 mg/kg). The activities of 3-methoxypropionamides, functionalized amino acids, and related compounds are discussed.     

Synthesis and opioid activity of [Sar4]dermorphin-tetrapeptide analogues

The modification of the dermorphin-(1-4)-tetrapeptide structure led to analogues with potent opioid activity in vitro and in vivo. [Sar4]Tetrapeptides such as H2N-CH(NH)-Tyr-D-Ala-Phe-Sar-D-NH-CH(CH3)C6H5 (VII) whose terminal amino group is replaced by the guanidino function and whose C-terminus is amidated by (R)-(+)-alpha-methylbenzylamine, show peripheral and central opioid activities comparable to or higher than those of dermorphin. The potency of VII in the different tests was as follows: guinea-pig ileum (GPI) IC50 = 0.09nM, mouse Vas deferens (MVD) IC50 = 0.69nM, tail-flick ED50 = 8.91 pmol/mouse, i.c.v. and 4.54 mumol/kg, s.c. This dermorphin-(1-4)-tetrapeptide derivative is about 650 and 950 times as active as morphine in the two in vitro tests, respectively. The MVD/GPI potency ratio of the new peptides suggests a mu-type agonist behaviour.     

Pharmacological effects of oral E6123, a novel PAF antagonist, on biological changes induced by PAF inhalation in guinea pigs.

The effects of a newly synthesized PAF antagonist E6123, (S)-(+)-6-(2-chlorophenyl)-3-cyclopropanecarbonyl-8,11-dimethyl-2, 3,4,5- tetrahydro-8H-pyrido[4',3':4,5]thieno[3,2-f][1,2,4]triazolo [4,3-a][1,4]diazepine, on in vivo inhaled PAF-induced pulmonary changes were investigated. E6123 inhibited PAF inhalation-induced bronchoconstriction in guinea pigs with an ED50 value (p.o.) of 1.3 micrograms/kg which was lower than those of other PAF-antagonists such as WEB2347 (ED50 = 26 micrograms/kg) and Y-24180 (ED50 = 12 micrograms/kg). E6123 significantly inhibited PAF inhalation-induced eosinophil infiltration into the bronchiole and trachea, and bronchial hyperreactivity in guinea pigs after oral administration at 1 and 10 micrograms/kg, respectively. E6123 inhibited the PAF-induced increase in intracellular free calcium ion concentration ([Ca2+]i) in guinea pig eosinophils with an IC50 value of 14 nM. The present results suggest that E6123 may be beneficial for the treatment of asthma, in which PAF is assumed to be involved.     

Control of pepsin secretion by regulatory peptides in the rat stomach: comparison with acid secretion.

Previous studies of the control of pepsin secretion by neurohumoral agents showed some discrepancies between in vitro (isolated cells) and in vivo experiments. In the present work, the effects on pepsin secretion of CCK, pentagastrin, secretin, VIP, neurotensin, histamine, and methacholine were reinvestigated in conscious gastric fistula rats, in comparison to acid secretion. ED50's and doses inducing maximal responses were measured to directly compare the potency and efficacy of these substances. Methacholine was the most efficient (maximal response = 4.5 x basal level, ED50 = 1.3 mumol/kg.h) and CCK the most potent (ED50 = 1.9 nmol/kg.h) stimulant, whereas secretin was a potent (ED50 regulators of pepsin secretion in the rat. Pentagastrin and histamine did not stimulate pepsin output, as found by others with isolated chief cells in vitro. Neurotensin and large doses of VIP marginally inhibited pepsin secretion.     

A Potential Mechanism of High-Dose Ticagrelor in Modulating Platelet Activity and Atherosclerosis Mediated by Thymic Stromal Lymphopoietin Receptor

Abnormal expression of thymic stromal lymphopoietin (TSLP) and its receptor (TSLPR) was found in patients with acute coronary syndrome. Ticagrelor, an oral platelet ADP P2Y12 receptor antagonist, is widely used in these patients. The aim of this study was to verify whether different doses of ticagrelor regulated plaque progression and platelet activity by modulating TSLP/TSLPR. Seventy-five ApoE-/- mice were randomly divided into five groups: (1) high-cholesterol diet (HCD, n = 15); (2) HCD plus ticagrelor 25 mg/kg/d (T1, n = 15); (3) HCD plus ticagrelor 50 mg/kg/d (T2, n = 15); (4) HCD plus ticagrelor 100 mg/kg/d (T3, n = 15); and (5) a normal diet group (ND, n = 15). At day 0 and at week 16, blood lipids and serum TSLP levels, expression of TSLPR, CD62, and CD63, platelet aggregation, platelet ATP release, PI3K/Akt signaling pathway, and plaque morphology were assessed. HCD increased TSLPR expression and atherosclerosis progression but high-dose ticagrelor (100 mg/kg) moderated this trend. TSLPR was positively correlated with Akt1, platelet aggregation, corrected plaque area, and vulnerability index in the T3 group (P<0.01). In conclusion, low-dose ticagrelor only inhibited platelet activity. Besides this inhibition, high-dose ticagrelor modulated platelet activity and atherosclerosis mediated by TSLPR, potentially through the PI3K/Akt signal pathway.     

Cytoprotective and antisecretory properties of a non-diarrheogenic and non-uterotonic prostacyclin analog: U-68,215

U-68,215 [15-Cyclohexyl-9-deoxo-13,14-dihydro-2',9 alpha-methano-4,5,6,16,17,18,19,20-octanor-3-oxa-3,7-(1', 3'-interphenylene)-PGE1] is a stable prostacyclin analog. When given orally to rats, it is cytoprotective for the stomach (ED50: 0.8 micrograms/kg) and the intestine (ED50: 22 micrograms/kg), is gastric antisecretory (ED50: 35 micrograms/kg) and antiulcer (aspirin) (ED50: 5 micrograms/kg). The oral antisecretory ED50 in dogs is 50 micrograms/kg. It has a long duration of gastric cytoprotection: 8-10 hours compared to 3 hours for 16,16-dimethyl PGE2. Unlike most prostaglandins of the E type, it is not diarrheogenic (not enteropooling), it does not induce cellular proliferation of the gastrointestinal mucosa, when given twice a day for eight days, it is not uterotonic (in monkeys), and it does not prevent embryo implantation in hamsters. It inhibits ex vivo platelet aggregation (ED50: 300 micrograms/kg), but does not promote bleeding from cut vessels nor from gastric ulcers. U-68,215 lowers blood pressure at an oral dose corresponding to 1-5 times the antisecretory ED50 in rats and dogs, and to 150 times the cytoprotective ED50 in rats. It may be of therapeutic value in the treatment of conditions where inhibition of gastric acid secretion is desirable, e.g., gastric and duodenal ulcer, and in conditions responding to cytoprotection, e.g., stress ulcers, hemorrhagic gastritis and gastric erosions associated with nonsteroidal antiinflammatory drugs.     

A kinetic study of the gill (Na+, K+)-ATPase, and its role in ammonia excretion in the intertidal hermit crab, Clibanarius vittatus

To better comprehend the role of gill ion regulatory mechanisms, the modulation by Na(+), K(+), NH(4)(+) and ATP of (Na(+), K(+))-ATPase activity was examined in a posterior gill microsomal fraction from the hermit crab, Clibanarius vittatus. Under saturating Mg(2+), Na(+) and K(+) concentrations, two well-defined ATP hydrolyzing sites were revealed. ATP was hydrolyzed at the high-affinity sites at a maximum rate of V=19.1+/-0.8 U mg(-1) and K(0.5)=63.8+/-2.9 nmol L(-1), obeying cooperative kinetics (n(H)=1.9); at the low-affinity sites, hydrolysis obeyed Michaelis-Menten kinetics with K(M)=44.1+/-2.6 mumol L(-1) and V=123.5+/-6.1 U mg(-1). Stimulation by Na(+) (V=149.0+/-7.4 U mg(-1); K(M)=7.4+/-0.4 mmol L(-1)), Mg(2+) (V=132.0+/-5.3 U mg(-1); K(0.5)=0.36+/-0.02 mmol L(-1)), NH(4)(+) (V=245.6+/-9.8 U mg(-1); K(M)=4.5+/-0.2 mmol L(-1)) and K(+) (V=140.0+/-4.9 U mg(-1); K(M)=1.5+/-0.1 mmol L(-1)) followed a single saturation curve and, except for Mg(2+), obeyed Michaelis-Menten kinetics. Under optimal ionic conditions, but in the absence of NH(4)(+), ouabain (K(I)=117.3+/-3.5 mumol L(-1)) and orthovanadate inhibited up to 67% of the ATPase activity. The inhibition studies performed suggest the presence of F(0)F(1), V- and P-ATPases, but not Na(+)-, K(+)- or Ca(2+)-ATPases as contaminants in the gill microsomal preparation. (Na(+), K(+))-ATPase activity was synergistically modulated by NH(4)(+) and K(+). At 20 mmol L(-1) K(+), a maximum rate of V=290.8+/-14.5 U mg(-1) was seen as NH(4)(+) concentration was increased up to 50 mmol L(-1). However, at fixed NH(4)(+) concentrations, no additional stimulation was found for increasing K(+) concentrations (V=135.2+/-4.1 U mg(-1) and V=236.6+/-9.5 U mg(-1) and for 10 and 30 mmol L(-1) NH(4)(+), respectively). This is the first report to detail ionic modulation of gill (Na(+), K(+))-ATPase in C. vittatus, revealing an asymmetrical, synergistic stimulation of the enzyme by K(+) and NH(4)(+), as yet undescribed for other (Na(+), K(+))-ATPases, and should provide a better understanding of NH(4)(+) excretion in pagurid crabs.     

Evaluation of medetomidine/ketamine for short-term immobilization of variable flying foxes (Pteropus hypomelanus)

Four medetomidine/ketamine (M/K) doses (30 microg/kg/3 mg/kg; 40/4; 50/5; 60/6), administered by intramuscular injection, were evaluated for short-term immobilization of adult male variable flying foxes (Pteropus hypomelanus). The highest dose (60 microg/kg/6 mg/kg) produced a significantly faster induction (31 +/- 46 sec) than the lowest dose (30/3) (125 +/- 62 sec). The highest dose levels (50/5, 60/6) produced significantly longer immobilization times (52.5 +/- 25.7 min and 60.6 +/- 20.8 min, respectively) than did the lower doses (30/3, 40/4) (18.8 +/- 8.7 min and 31.0 +/- 14.3 min, respectively). The dose at which 50% of the bats were immobilized for > or = 30 min (ED(50)) was approximately 40 microg/kg/4 mg/kg. This dose produced a mean immobilization time of 31 +/- 14 min, bradypnea and bradycardia. In conclusion, a M/K dose of 50 microg/kg/5 mg/kg is recommended for greater than 30 min of relaxed immobilization in free-living variable flying foxes and is sufficient for safe collection of samples.     

Use of forskolin to study the relationship between cyclic AMP formation and bone resorption in vitro.

The effect of the adenylate cyclase activator forskolin on bone resorption and cyclic AMP accumulation was studied in an organ-culture system by using calvarial bones from 6-7-day-old mice. Forskolin caused a rapid and fully reversible increase of cyclic AMP, which was maximal after 20-30 min. The phosphodiesterase inhibitor rolipram (30 mumol/l), enhanced the cyclic AMP response to forskolin (50 mumol/l) from a net cyclic AMP response of 1234 +/- 154 pmol/bone to 2854 +/- 193 pmol/bone (mean +/- S.E.M., n = 4). The cyclic AMP level in bones treated with forskolin (30 mumol/l) was significantly increased after 24 h of culture. Forskolin, at and above 0.3 mumol/l, in the absence and the presence of rolipram (30 mumol/l), caused a dose-dependent cyclic AMP accumulation with an calculated EC50 (concentration producing half-maximal stimulation) value at 8.3 mumol/l. In 24 h cultures forskolin inhibited spontaneous and PTH (parathyroid hormone)-stimulated 45Ca release with calculated IC50 (concentration producing half-maximal inhibition) values at 1.6 and 0.6 mumol/l respectively. Forskolin significantly inhibited the release of 3H from [3H]proline-labelled bones stimulated by PTH (10 nmol/l). The inhibitory effect by forskolin on PTH-stimulated 45Ca release was significant already after 3 h of culture. In 24 h cultures forskolin (3 mumol/l) significantly inhibited 45Ca release also from bones stimulated by prostaglandin E2 (1 mumol/l) and 1 alpha-hydroxycholecalciferol (0.1 mumol/l). The inhibitory effect of forskolin on spontaneous and PTH-stimulated 45Ca release was transient. A dose-dependent stimulation of basal 45Ca release was seen in 120 h cultures, at and above 3 nmol of forskolin/l, with a calculated EC50 value at 16 nmol/l. The stimulatory effect of forskolin (1 mumol/l) could be inhibited by calcitonin (0.1 unit/ml), but was insensitive to indomethacin (1 mumol/l). Forskolin increased the release of 3H from [3H]proline-labelled bones cultured for 120 h and decreased the amount of hydroxyproline in bones after culture. Forskolin inhibited PTH-stimulated release of Ca2+, Pi, beta-glucuronidase and beta-N-acetylglucosaminidase in 24 h cultures. In 120 h cultures forskolin stimulated the basal release of minerals and lysosomal enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Discovery and stereoselective synthesis of the novel isochroman neurokinin-1 receptor antagonist 'CJ-17,493'

A novel central nervous system (CNS) selective neurokinin-1 (NK(1)) receptor antagonist, (2S,3S)-3-[(1R)-6-methoxy-1-methyl-1-trifluoromethylisochroman-7-yl]-methylamino-2-phenylpiperidine 'CJ-17,493' (compound (+)-1), was synthesized stereoselectively using a kinetic resolution by lipase-PS as a key step. Compound (+)-1 displayed high and selective affinity (K(i)=0.2 nM) for the human NK(1) receptor in IM-9 cells, potent activity in the [Sar(9), Met(O(2))(11)]SP-induced gerbil tapping model (ED(50)=0.04 mg/kg, s.c.) and in the ferret cisplatin (10mg/kg, i.p.)-induced anti-emetic activity model (vomiting: ED(90)=0.07 mg/kg, s.c.), all levels of activity comparable with those of CP-122,721. In addition, compound (+)-1 exhibited linear pharmacokinetics rather than the super dose-proportionality of CP-122,721 and this result provides a potential solution for the clinical issue observed with CP-122,721.     

Discovery of novel, orally active dual NK1/NK2 antagonists

Exploration of the SAR around selective NK2 antagonists, SR48968 and ZD7944, led to the discovery that naphth-1-amide analogues provide potent dual NK1 and NK2 antagonists. ZD6021 inhibited binding of [3H]-NKA or [3H]-SP to human NK1 and NK2 receptors, with high-affinity (K(i)=0.12 and 0.62nM, respectively). In functional assays ZD6021 had, at 10(-7)M, in human pulmonary artery pK(B)=8.9 and in human bronchus pK(B)=7.3, for NK1 and NK2, respectively. Oral administration of ZD6021 to guinea pigs dose-dependently attenuated ASMSP induced extravasation of plasma proteins, ED(50)=0.5mg/kg, and NK2 mediated bronchoconstriction, ED(50)=13mg/kg.     

Evaluation of the eutomer of 4-{3-(4-chlorophenyl)-3-hydroxypyrrolidin-1-yl}-1-(4-fluorophenyl)butan-1-one, {(+)-SYA 09}, a pyrrolidine analog of haloperidol

Enantiomeric separation of the racemic 4-{3-(4-chlorophenyl)-3-hydroxypyrrolidin-1-yl}-1-(4-fluorophenyl)butan-1-one, a pyrrolidine analog of haloperidol, {(+/-)-SYA 09}, and subsequent binding studies revealed that most of the binding affinity at dopamine and serotonin receptors resides in the (+)-isomer {(+)-SYA 09} or the eutomer. Further pharmacological evaluation of the eutomer revealed that it has a higher affinity for the dopamine D4 (DAD4) receptor subtype (Ki = 3.6 nM) than for the DAD2 subtype (Ki = 51.1 nM) with a ratio of 14.2 (D2Ki/D4Ki ratio = 14.2). In an animal model of antipsychotic efficacy, the (+)-SYA 09 was efficacious with an ED50 value of 1.6 mg/kg, i.p., and at twice this value, (+)-SYA 09 did not induce significant catalepsy in rats.     

EDRF对PE引起的大鼠主动脉缩血管效应的作用

本文研究ＥＤＲＦ（ｅｎｄｏｔｈｅｌｉｕｍ－ｄｅｒｉｖｅｄｒｅｌａｘｉｎｇｆａｃｔｏｒ,ＥＤＲＦ）对ＰＥ（ｐｈｅｎｙｌｅｐｈｒｉｎｅ）引起的大鼠主动脉收缩反应的影响。内皮完整和去内皮的大鼠主动脉环悬挂于器官浴槽中,测定血管的张力和收缩速度的变化。所有的实验在消炎痛（ｉｎｄｏｍｅｔｈａｃｉｎ,１０μｍｏｌ／Ｌ）存在下进行。用美兰（ｍｅｔｈｙｌｅｎｅｂｌｕｅ,ＭＢ,１０μｍｏｌ／Ｌ）或左旋硝基精氨酸（ＮＧ－ｎｉｔｒｏ－Ｌ－ａｒｇｉｎｉｎｅ,Ｌ－ＮＮＡ,３０μｍｏｌ／Ｌ）处理内皮完整的大鼠主动脉环,ＰＥ的剂量－收缩张力曲线明显左移,ＥＣ３０值均降低５倍,最大反应比率分别为１．６±０．４和１．６±０．５。在去内皮的大鼠主动脉环中,经ＭＢ和Ｌ－ＮＮＡ处理后,仍可见ＥＣ３０下降３倍,最大反应比率均为１．０±０．２。后者可能与血管平滑肌产生少量ＥＤＲＦ有关。我们的结果提示ＰＥ对血管的收缩反应也受血管内皮和平滑肌产生的ＥＤＲＦ的调控