Pharmacokinetics and safety of roledumab, a novel human recombinant monoclonal anti-RhD antibody with an optimized Fc for improved engagement of FCγRIII, in healthy volunteers.

BACKGROUND AND OBJECTIVES: A human recombinant monoclonal anti-RhD IgG may be useful to prevent RhD allo-immunization. Roledumab is such an antibody with a glycosylation pattern optimized for biological activity. The objective of the study was to assess the safety and pharmacokinetics of roledumab in healthy RhD-negative volunteers. MATERIALS AND METHODS: A total of 46 subjects received doses of 30-3000 µg i.v. of roledumab or placebo using a double-blind escalating single-dose design; 12 of these subjects also received 300 µg i.m. of roledumab. Subjects were followed for 6 months after administration. Serum roledumab concentrations were determined using flow cytometry. RESULTS: Fourteen treatment-emergent adverse events related to treatment were reported in nine subjects, with no apparent difference in their frequency or nature after placebo or roledumab administration. No anti-roledumab antibodies were detected. AUC(last) increased from 4·4 ng/ml.day at 30 µg i.v. to 2257 ng/ml.day at 3000 g i.v. The t(½) ranged from 18 to 22 days, and the absolute bioavailability after i.m. administration was between 73% and 80%. CONCLUSION: Roledumab is safe and well tolerated in healthy RhD-negative volunteers and shows a pharmacokinetic profile similar to that of polyclonal anti-RhD immunoglobulin.

Isolation, cloning, and expression of a new murine zinc finger encoding gene.

With the aim of identifying genes involved in cartilage differentiation, we have used a subtractive hybridization strategy with cDNAs from a chondrocytic cell line (MC615) and mRNAs from a mesenchymal precursor cell line (10T1/2). We have isolated a cDNA clone representing a novel mouse gene. The predicted 368-amino acid protein, designated ZF-12, contains four C(2)H(2)-type zinc finger motifs and one region homologous to the LeR domain, a finger-associated structural domain. ZF-12 mRNAs are expressed during embryonic development and in different organs in adult, including rib cartilage. These data suggest that ZF-12 might play an important role not only in cartilage differentiation, but also in basic cellular processes.

FruR-mediated transcriptional activation at the ppsA promoter of Escherichia coli.

The start site of transcription of the ppsA gene, whose expression is controlled by the regulatory protein FruR in Escherichia coli, was determined by primer extension of in vivo transcripts. The interactions of the ppsA promoter with either RNA polymerase or FruR factor were analysed by the base removal method. Our results indicate that: (i) the RNA polymerase binding site has a -10 extended module but lacks its -35 hexamer; (ii) FruR binds to a target DNA region centered around position -45.5 upstream of the ppsA gene. In addition, circular permutation analysis showed that, upon binding to its site, FruR induces a sharp bend of 120 degrees in the DNA helix, which suggests a crucial involvement of FruR-induced bending in ppsA promoter activation. Direct contacts between the upstream activating DNA and RNA polymerase were studied in an in vitro transcription assay by using reconstituted RNA polymerase mutants containing Ala substitutions in C-terminal domain of their alpha subunit. The alpha[L262A], alpha[R265A] and alpha[N268A] substitutions, which caused the most drastic reduction in the FruR-mediated activation of the ppsA promoter, had previously been shown to inhibit the upstream element-mediated activation at the rrnBP1 promoter.

Role of angiotensin subtype 2 receptor in neointima formation after vascular injury.

The role of angiotensin receptor subtypes 1 and 2 was assessed on neointima formation after injury in rat carotid artery. The effects of angiotensin converting enzyme inhibition by perindopril (3 mg.kg-1 x day-1 p.o.) and selective blockade of angiotensin subtype 1 receptors by DuP 753 (5 and 30 mg.kg-1 x day-1 p.o.) were compared on proliferative response to balloon injury. In rats treated 6 days before and for 14 days after injury, perindopril significantly reduced (-76%, p < 0.01) myointimal hyperplasia. In contrast, DuP 753 at 5 mg.kg-1 x day-1 did not modify the hyperplastic response to balloon catheterization. Only at 30 mg.kg-1 x day-1 was DuP 753 able to reduce neointima formation (-47%, p < 0.05). This dose was equipotent to perindopril on the renin-angiotensin system as assessed by the pressor response to angiotensin II and angiotensin I. Therefore, blockade of subtype 1 receptors was a less effective means of suppression of myointimal growth than angiotensin converting enzyme inhibition, suggesting that another angiotensin receptor subtype or converting enzyme substrates are involved in this process. For the determination of whether angiotensin subtype 2 receptors were implicated, the specific subtype 2 receptor antagonist CGP 42112A (1 mg.kg-1 x day-1) was continuously infused perivascularly for 14 days in the vicinity of the injured carotid artery. CGP 42112A was as effective in preventing neointima formation as perindopril (-73%, p < 0.01, versus -76%, p < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of beta-adrenergic receptors by tertatolol: an additional mechanism for beta-adrenergic blockade.

Tertatolol is a potent new beta-blocker with no intrinsic sympathomimetic activity or beta 1/beta 2-receptor subtype selectivity. When given at therapeutic doses (5 mg/day) to human subjects it induced a reduction in the beta-adrenergic receptor number measured by 3H-CGP 12177 specific binding, without any change in the affinity on intact lymphocytes. This reduction was seen 7 hours (54%), 24 hours (35%), and 48 hours (30%) after a single drug dose. A similar receptor reduction was observed 7 hours (42%), 24 hours (37%), and 48 hours (15%) after 14 doses of the drug. In parallel, the pharmacologic efficacy of the drug was evident from the reduction in supine and upright heart rates and after submaximal exercise; heart rate was reduced to the same extent after single or repeated drug doses. The reduction of receptor number correlated well with the reduction in heart rate in the supine (P less than 0.001) and upright (P less than 0.01) positions and after exercise (P less than 0.02). In in vitro competitive binding experiments tertatolol was found to be a competitive inhibitor of beta-adrenergic receptors. However, on intact human lymphocytes preincubated with this drug, tertatolol reduced the density of beta-adrenergic receptors. We conclude that tertatolol, besides competitively inhibiting beta-adrenergic receptors, induced a marked and lasting decrease in the beta-adrenergic receptor number. This effect may be important for its beta-blocking effects.

Detection of an extended-10 element in the promoter region of the pckA gene encoding phosphoenolpyruvate carboxykinase in Escherichia coli.

The regulation of transcription of the pckA gene coding for phosphoenolpyruvate carboxykinase in Escherichia coli was analysed by site-directed mutagenesis of the promoter region and measurement of in vitro transcription initiation. Mutation of the guanine residue at position -14 to either cytosine or thymine was found to result in a drastic decrease of transcription, even in the presence of the natural -35 hexamer TTTCCA that differs by only two nucleotides from the consensus sequence TTGACA. It was concluded that the promoter region of pckA contains an extended -10 module, 5'-TG-3', located one base upstream of the -10 hexamer, which is crucial for transcription.

Acute central and renal haemodynamic responses to tertatolol and propranolol in patients with arterial hypertension following head injury.

We compared the central and renal haemodynamic effects of tertatolol, a new non-cardioselective beta-adrenergic blocking drug without partial agonist activity, with those of an equipotent dosage of propranolol in two groups of 10 patients each with acute cerebral injury who had developed systemic hypertension. After tertatolol, 5 mg orally, mean arterial pressure was unchanged, heart rate decreased by 22% (P less than 0.01) and cardiac index by 24% (P less than 0.01), while renal blood flow remained unchanged (-5%, NS). After 160 mg propranolol orally, mean arterial pressure was unchanged, heart rate decreased by 12% (P less than 0.01), cardiac index by 16% (P less than 0.01) and renal blood flow by 17% (P less than 0.01). There was a moderate rise in norepinephrine levels after tertatolol only. Thus in this particular model of acute hypertension, tertatolol acted as a potent beta-blocking agent but differed from propranolol by preserving renal perfusion.

New triazine derivatives as potent modulators of multidrug resistance.

A series of 70 triazine derivatives have been synthesized and tested for their capacity to modulate multidrug resistance (MDR) in DC-3F/AD and KB-A1 tumor cells in vitro, in comparison with verapamil (VRP), a calcium channel antagonist currently used in therapy as an antihypertensive drug, which also shows MDR modulating activity. Among the 12 selected compounds, 16 (S9788) showed high MDR reversing properties in vitro (300- and 6-fold VRP at 5 microM in DC-3F/AD and KB-A1 cells, respectively) and induced a strong accumulation of adriamycin. The relationship between the increase of ADR accumulation and the fold reversal induced by these compounds and their lack of effects on the sensitive DC-3F cells suggest that they act mainly by inhibiting the P-glycoprotein (Pgp) catalyzed efflux of cytotoxic agents, as already described for a majority of MDR modulators. In vivo, in association with the antitumor drug vincristine (0.25 mg/kg), 16 (100 mg/kg) increased the T/C by 39% in mice bearing the resistant tumor cell line P388/VCR. According to these interesting properties, 16 was selected for a clinical development because it was more bioavailable than 34, even though it was less active.

New N alpha-guanidinobenzoyl derivatives of hirudin-54-65 containing stabilized carboxyl or phosphoryl groups on the side chain of phenylalanine-63.

We report on the synthesis and pharmacological properties of a new series of thrombin inhibitors derived from hirudin carboxyl-terminal fragments. Two (arylphosphono)phenylalanines, p-PO3H2-L-Phe1 and m-PO3H2-L-Tyr, and one (carboxymethyl)phenylalanine, p-CH2COOH-L-Phe, were prepared and incorporated into position 63 of the modified hirudin's C-terminal dodecapeptide using the Fmoc solid-phase synthesis strategy. Substitution by any one of the residues led to very active analogs which doubled the thrombin time at low micromolar concentration (Ctt2) in vitro (1 microM < Ctt2 < 3 microM) and potently increased the activated partial thromboplastin time (APTT) ex vivo. These compounds displayed a higher potency in vitro and a longer duration of action in vivo than both the corresponding sulfated or phosphorylated tyrosine counterparts.

Synthesis and evaluation of 9-hydroxy-5-methyl-(and 5,6-dimethyl)-6H-pyrido[4,3-b]carbazole-1-N- [(dialkylamino)alkyl]carboxamides, a new promising series of antitumor olivacine derivatives.

Starting from 2-(2-aminoethyl)-6-methoxy-1-methylcarbazole, ethyl 9-methoxy-5-methyl-6H-pyrido[4,3-b]carbazole-1-carboxylate was obtained through a three-step sequence. This compound and its 6-methyl derivative react with (dialkylamino)alkylamines to provide various 9-methoxy-5-methyl-6H-pyrido[4,3-b]carbazole-1-(N-substituted carboxamides) whose boron tribromide demethylation afforded corresponding 9-hydroxy-1-(N-substituted carbamoyl)-olivacines. The same pathway but starting from 2-(2-aminoethyl)-6-methoxy-1,4-dimethylcarbazole led to ethyl 9-methoxy-5,11-dimethyl-6H-pyrido[4,3-b]carbazole-1-carboxylate which did not normally react with amines. It provided either the recovered starting material at 120 degrees C or 9-methoxyellipticine resulting from an unexpected decarboethylation in a steel vessel at 180 degrees C. Biological testing of the newly obtained 1-carbamoylolivacine derivatives showed that 9-hydroxylated compounds displayed high cytotoxicity for cultured L1210 and colon 38 cells (IC50 range 5-10 nM) and good antitumor activity in vivo in the P388 leukemia and colon 38 models when administered by the iv route. The most active compound in these series is 9-hydroxy-5,6-dimethyl-1-[N-[2-(dimethylamino)ethyl]carbamoyl]-6H- pyrido[4,3-b]carbazole which was selected for further evaluation on murine solid tumors and for toxicological studies.

Electrophysiological effects of S 16257, a novel sino-atrial node modulator, on rabbit and guinea-pig cardiac preparations: comparison with UL-FS 49.

1. S 16257 is a new bradycardic agent. Its electropharmacological profile has been compared to that of the known bradycardic compound UL-FS 49 (Zatebradine). Intracellular recordings of action potentials (APs) were performed with conventional glass microelectrodes. 2. In the rabbit isolated sino-atrial node (SAN) tissue, S 16257 and UL-FS 49 (1 microM, 3 microM and 10 microM) were equipotent in slowing spontaneous APs firing predominantly by decreasing the rate of diastolic depolarization (at 3 microM, -23.8 +/- 3.9% and -27.9 +/- 2.6%, respectively). For the two compounds a maximal effect was obtained at 3 microM. In these preparations, action potential duration at 50% of total repolarization (APD50) was more affected by UL-FS 49 than S 16257 at any concentration tested (at 3 microM, +8.9 +/- 2.9% and +29.1 +/- 3.7% for S 16257 and UL-FS 49, respectively; P < or = 0.01). 3. To estimate the direct effects on AP duration, driven cardiac preparations were exposed to these agents. In guinea-pig papillary muscles, paced at a frequency of 1 Hz, increasing concentrations of S 16257 or UL-FS 49 (0.1 to 10 microM, 30 min exposure for each concentration) slightly prolonged AP repolarization. This prolongation was more marked for UL-FS 49 (at 1 microM, +6.1 +/- 0.6% and +11.2 +/- 1.3% elevation of APD50, for S 16257 and UL-FS 49, respectively). 4. Application of UL-FS 49 (3 microM) to rabbit Purkinje fibres, triggered at a frequency of 0.25 Hz, induced a marked prolongation of APD50 and APD90 (+149.4 +/- 51.2% and +86.0 +/- 15.4%, respectively). S 16257 (3 MicroM) induced only a weak prolongation of AP (+ 14.1 +/- 5.0% and + 14.8 +/- 3.3% for APD50 and APD90, respectively) significantly smaller than in the case of UL-FS 49.5. These results show that S 16257 slows the rate of spontaneous AP firing in isolated SAN mainly by a reduction of the diastolic depolarization of the cells, which suggests an inhibition of the pace-maker current (If). S 16257 and UL-FS 49 are equipotent in their bradycardic effect but S 16257 is more specific as it induces less increase in myocardial repolarization time.

Cardiopulmonary effects of a single oral dose of almitrine at rest and on exercise in patients with hypoxic chronic airflow obstruction.

Almitrine, a new triazine derivative, was studied in a double-blind, randomized, parallel study in 16 patients with hypoxic chronic airflow obstruction (eight almitrine and eight placebo). At rest, compared to placebo, a 3 mg/kg single dose of almitrine given orally significantly increased the partial pressure of oxygen (mean increase: +12.0 +/- SEM 2.1 mm Hg, p less than 0.001) and decreased the partial pressure of carbon dioxide (mean decrease: -6.0 +/- 0.7 mm Hg, p less than 0.001); this improvement in arterial blood gases persisted on exercise. The lack of significant change in ventilation and the decrease in the alveolar-arterial oxygen gradient (mean decrease -10.0 +/- 1.9 mm Hg; p less than 0.001) at rest suggests a change in the distribution of the ventilation-perfusion ratio in the lung; such a change was confirmed by a krypton 81m isotopic study. Pulmonary hemodynamic responses were studied at rest and on exercise; a significant but slight increase in mean pulmonary artery pressure at rest (+4.0 +/- 1.5 mm Hg, p less than 0.05) was found.

The Tertatolol International Multicenter Study (T.I.M.S.). Predicting factors of an efficient therapy.

The Tertatolol International Multicenter Study (T.I.M.S.) was aimed at assessing the efficacy and tolerability of 5 mg tertatolol (T) once daily over a one year period and at finding, among the clinical variables before treatment, parameters predicting a successful single beta-blocking therapy. The study was carried out in 230 patients (96 men, 134 women, mean age +/- standard error of the mean: (51.5 +/- 0.7 years) suffering from uncomplicated mild to moderate hypertension. After a one-month placebo run-in period (M0-M1) and a one-month double-blind placebo-controlled period (M1-M2), 213 patients entered and 166 completed the one-year open period (M2-M14). A diuretic (D) was added if blood pressure (BP) was inadequately controlled with the single therapy. After one year, 88.5% of patients were controlled (sitting diastolic BP less than or equal to 90 mm Hg): 56.3% on single therapy (T) and 32.2% on dual therapy (T + D), respectively. Statistical analysis performed on the controlled subjects showed that patients who were controlled with T alone had an initially lower standing diastolic BP and a higher standing heart rate, were younger and had a lower sitting systolic BP than those controlled with T + D. Using such discriminant parameters which are predictors, 83.5% patients (single therapy group) and 49% patients (dual therapy group) were classified in the therapeutic group to which they really belonged. This study confirms the antihypertensive efficacy of tertatolol, and highlights relevant parameters for a successful single beta-blocker therapy in clinical practice.

Effect of tertatolol on glomerular hemodynamics in the normal Munich-Wistar rat.

Administration of beta-blockers is frequently associated with decreases in both renal plasma flow and glomerular filtration rate (GFR). Tertatolol, a new non-selective beta-blocker, has demonstrated similar systemic effects to other conventional beta-blockers, but tertatolol produces increases in both renal plasma flow and glomerular filtration rate. To evaluate the renal hemodynamic mechanism responsible for the increase in GFR, micropuncture experiments were performed in normal Munich-Wistar rats. Intravenous injection of tertatolol produced a significant increase in GFR and urinary sodium excretion in spite of a decrease in systemic blood pressure. Single nephron glomerular filtration rate was significantly increased due to an increase in single nephron plasma flow related to parallel afferent and efferent arteriolar dilatation. No significant changes in glomerular hydrostatic pressure, transcapillary hydrostatic pressure gradient or the ultrafiltration coefficient were demonstrated with tertatolol. The capacity of tertatolol to increase glomerular filtration rate and to promote sodium excretion without modifying critical glomerular pressures makes this agent a highly attractive antihypertensive drug.

Acute effects of tertatolol and nadolol on systemic and renal hemodynamics in patients with essential hypertension.

The acute systemic and renal hemodynamic effects of tertatolol, a new noncardioselective beta-blocker without partial agonist activity, were compared to those of an equipotent dose of nadolol in eight patients with essential hypertension. Tertatolol (5 mg) or nadolol (80 mg) were administered orally at an interval of 1 week in a random order as a double-blind, cross-over study. Cardiac output was measured by Doppler echography, and renal blood flow and glomerular filtration rate were measured by constant infusion techniques using 123I-iodohippurate and 51CR-EDTA, respectively. Measurements were performed before and then successively 2 and 4 hours after ingestion of the drugs. Both nadolol and tertatolol decreased blood pressure and cardiac output to a comparable extent. Renal blood flow remained unchanged, so that the renal fraction of cardiac output increased from 14.4 +/- 1.5% to 21.3 +/- 2% after nadolol and from 14.8 +/- 2.4% to 20.5 +/- 1.8% after tertatolol (mean +/- SE, P less than 0.01 before vs. after; nadolol vs. tertatolol was not significant). The glomerular filtration rate remained unchanged, from 68 +/- 9 to 64 +/- 6 mL/min.m2 after nadolol and from 71 +/- 8 to 67 +/- 7 mL/min.m2 after tertatolol (before vs. after and nadolol vs. tertatolol levels were not significant). These results show that both tertatolol and nadolol redistribute cardiac output to the kidneys in patients with essential hypertension.

Selective infusion of tertatolol into the renal artery induces a local vasodilator effect in humans. Demonstration by the continuous thermodilution method.

The effects of tertatolol on renal circulation were studied in 8 patients with normal renal function. Left renal blood flow was measured by the continuous thermodilution method before (t0), and 5 (t1), 10 (t2) and 20 (t3) min after a selective infusion of 0.25 mg of tertatolol into the left renal artery. During the study, cardiac output, heart rate, aortic and right atrial pressures, systemic vascular resistances and the systemic arteriovenous oxygen difference were not significantly altered. Plasma renin activity and plasma aldosterone in arterial and renal venous blood started to decrease at t1. At t3, renal blood flow was increased (from 463 +/- 28 mL/min at t0, to 549 +/- 22 mL/min, P less than .001), renal vascular resistance was reduced (from 188 +/- 17 mm Hg/L/min at t0 to 156 +/- 15 mm Hg/L/min, P less than .01) and the arteriovenous oxygen difference was decreased (from 1.6 +/- 0.2 mL/100 mL at t0 to 1.1 +/- 0.1 100 mL, P less than .01). The renal/cardiac flow ratio increased from 10.0 +/- 2.2% to 11.7 +/- 2.1% (P less than .05) and the renal/systemic vascular resistance ratio decreased from 10.5 +/- 2.0 to 8.7 +/- 1.4 (P less than .01). These data show that selective infusion of a low dose of tertatolol into the renal artery results in an increase in renal blood flow which is delayed and occurs without concomitant changes in systemic hemodynamics. This suggests an intrarenal mechanism of action in humans supporting the previously observed renal vasodilation induced by tertatolol in isolated perfused animal kidneys.

Preserved renal perfusion during beta blockade by tertatolol with and without cyclooxygenase inhibition in normal humans.

The systemic and renal hemodynamic effects of tertatolol, a new noncardioselective beta blocker without partial agonist activity, given alone or in combination with cyclooxygenase inhibition by acetylsalicylic acid (aspirin), were investigated in eight healthy volunteers. Tertatolol 5 mg, aspirin 1 g, tertatolol 5 mg together with aspirin 1 g and placebo were administered at 1-week intervals in a random order and in a double-blind fashion. Cardiac output was measured by Doppler echography and renal blood flow and glomerular filtration rate (GFR) by constant infusion techniques using (123I) iodohippurate and (51Cr) EDTA, respectively. Measurements were performed before and then successively 2 and 4 hours after oral intake of drugs or placebo. Tertatolol decreased cardiac output by 22% (P less than .05) and heart rate by 17% (P less than .05) without change in blood pressure, renal blood flow, and GFR. The same effects occurred when tertatolol was given together with aspirin. Either placebo or aspirin alone had no effect on systemic and renal hemodynamics. These results suggest that cardiac output is redistributed to the kidneys after tertatolol intake in normal humans. This favorable effect on renal hemodynamics is probably not mediated by a local release of vasodilating prostaglandins.

Beta blockers induce different intrarenal effects in humans: demonstration by selective infusion of tertatolol and propranolol.

The effects of tertatolol and propranolol on renal circulation were studied in patients with normal renal function to test the hypothesis that various beta blockers may have different vasomotor effects within the renal vascular bed. Left renal blood flow was measured by the continuous thermodilution method before (t0), and 5 (t1), 10 (t2), 20 (t3), and 30 (t4) minutes after a selective infusion of tertatolol (0.25 mg, N = 4) or propranolol (2.5 mg, N = 4) into the left renal artery. Heart rate, cardiac output, aortic and right atrial pressures, and systemic vascular resistances did not significantly vary after either drug throughout the study. Plasma renin activity and plasma aldosterone in arterial and renal venous blood started to decrease at t1 after each drug. After propranolol, renal blood flow, renal vascular resistance and the renal arteriovenous oxygen difference were unchanged. Conversely, after tertatolol at t3, renal blood flow was increased (from 426 +/- 18 mL/min/1.73 m2 to 509 +/- 56 mL/min/1.73 m2, P = .03), renal vascular resistance and renal arteriovenous oxygen difference were decreased (P less than .001), and the renal blood flow/cardiac output ratio was increased (P = .03). The filtration fraction did not vary after either drug, as attested by the unchanged polyfructosan extraction coefficient. This clinical study shows that selective infusion of a single low dose of tertatolol into the renal artery results in a delayed intrarenal vasodilator effect, while at the dose tested propranolol does not modify renal hemodynamics.

S 14297, a novel selective ligand at cloned human dopamine D3 receptors, blocks 7-OH-DPAT-induced hypothermia in rats.

The selective dopamine D3 receptor agonist, 7-OH-DPAT ((+)-7-hydroxy-2-(di-n-propylamino)tetralin) and the novel naphthofurane, S 14297 ((+)-[7-(N,N-dipropylamino)-5,6,7,8-tetrahydro- naphtho(2,3b)dihydro,2,3-furane]), bound with high affinity and selectivity to recombinant, human dopamine D3 versus D2 receptors stably transfected into Chinese hamster ovary cells: Ki values = 2 versus 103 nM for 7-OH-DPAT and 13 versus 297 nM for S 14297. In contrast, the putative dopamine D3 receptor antagonist, AJ 76 (cis-(+)-5-methoxy-1-methyl-2-(n- propylamino)tetralin), displayed low affinity and selectivity for dopamine D3 versus D2 sites (70 versus 154 nM). 7-OH-DPAT (0.01-0.16 mg/kg s.c.) provoked hypothermia in rats, an action abolished by S 14297 (0.04-0.63 mg/kg s.c.) and, less potently, by AJ 76 (0.16-2.5 mg/kg s.c.). S 14297 (20.0 mg/kg s.c.) did not modify prolactin secretion. These data suggest that dopamine D3 receptors mediate hypothermia in the rat and that S 14297 acts as a selective antagonist at these sites.

In vitro and in vivo pharmacology of S 16474, a novel dual tachykinin NK1 and NK2 receptor antagonist.

Since tachykinins released from lung sensory nerve endings are thought to play a role in inflammatory diseases of airways via NK1 and NK2 receptors, dual tachykinin NK1 and NK2 receptor antagonists may have a great therapeutic potential. In vitro, the cyclopeptide S 16474 (cyclo-[Abo-Asp(D-Trp(Suc0Na)-Phe-N-(Me)Bzl)]) bound to both human tachykinin NK1 and NK2 receptors expressed in two lines of transfected Chinese hamster ovary cells (IC50 values 85 nM and 129 nM, respectively), while showing a poor affinity for the rat tachykinin NK1 receptor. S 16474 inhibited the contractions induced by substance P in isolated rabbit vena cava (pA2 7.0) and by neurokinin A in rabbit pulmonary artery (pA2 5.6). In vivo in anaesthetized guinea-pigs, S 16474 was found to dose dependently inhibit the bronchoconstrictions induced by intravenously administered substance P, neurokinin A and capsaicin. Plasma extravasation evoked in bronchi by endogenously released tachykinins under vagus nerve stimulation was abolished by S 16474 (10 mu mol/kg i.v.). These results demonstrate clearly that S 16474 is a tachykinin receptor antagonist exhibiting, in vitro and in vivo, a dual inhibitory effect on NK1 and NK2 receptors.