Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of neutral endopeptidase inhibition (NEP-I) were studied in 6 conscious sheep with heart failure (HF) induced by rapid ventricular pacing for 7 days. Measurements were performed 1 h before and for 6 h after intravenous (i.v.) bolus administration of vehicle and SCH 39370 (1.25 and 5 mg/kg) on separate days. After the higher dose, an index of serum NEP activity decreased from 0.83 +/- 0.05 to 0.13 +/- 0.07 nmol/ml/min (p less than 0.001) at 1 h and then returned to control levels at 6 h. Plasma atrial natriuretic peptide (ANP) and cyclic GMP rose from 328 +/- 28 and 20.2 +/- 4.3 to a peak of 570 +/- 65 pmol/L (p less than 0.001) and 28.7 +/- 6.3 nmol/L (p less than 0.05) respectively. Natriuresis and diuresis were significant and left atrial pressure (LAP) decreased from 21.9 +/- 1.1 to 20.1 +/- 0.8 mm Hg (p less than 0.05). Despite high endogenous ANP levels in HF, NEP-I further increases both ANP and its "second messenger." Its natriuretic and hemodynamic effects are consistent with enhanced ANP activity in renal and vascular tissues, suggesting that NEP-I may be useful for treating HF.
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PMID:Acute hemodynamic, hormonal, and renal effects of neutral endopeptidase inhibition in ovine heart failure. 138 Jun 8

Our studies with the prototypical NEP inhibitor SCH 34826 indicate the potential role of this class of compounds in cardiovascular modulation. The data assembled to date indicate that NEP inhibition elicits significant ANF-like effects in animals and man. The early data generated to date on SCH 34826, when considered with those data generated on other NEP inhibitors, indicate that NEP inhibition may have therapeutic utility in some forms of hypertension and congestive heart failure.
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PMID:SCH 34826: an overview of its profile as a neutral endopeptidase inhibitor and ANF potentiator. 183 84

Inhibition of the enzyme neutral metalloendopeptidase potentiates responses to atrial natriuretic factor and elicits reductions of blood pressure in desoxycorticosterone acetate sodium hypertensive rats. The present study evaluated the role of atrial natriuretic factor and bradykinin in the antihypertensive response to neutral metalloendopeptidase inhibition through the use of antibodies and antagonists, respectively. In addition, the pharmacokinetic mechanism by which neutral metalloendopeptidase inhibition interferes with atrial natriuretic factor metabolism was explored. The antihypertensive response to the neutral metalloendopeptidase inhibitor SCH 34826 was abruptly reversed by i.v. injection of a polyclonal antiserum to atrial natriuretic factor. In contrast, the antihypertensive response to SCH 34826 was unaffected by injection of the bradykinin antagonist Thi5,8-D-Phe7 bradykinin. The renal response to atrial natriuretic factor, SCH 34826, and phosphoramidon was inhibited by the bradykinin antagonist. The NEP inhibitor SCH 39370 significantly delayed the disappearance of TCA precipitable radioactivity from plasma following i.v. bolus dosing with 125I-labelled ANF 99-126. The effects were enhanced in the presence of the C receptor ligand. The results indicate that atrial natriuretic factor, but not bradykinin, plays an important role in the antihypertensive response to SCH 34826. Bradykinin plays a permissive role in the diuretic responses to atrial natriuretic factor and inhibitors of neutral metalloendopeptidase. Lastly, neutral metalloendopeptidase inhibition significantly alters the clearance and metabolism of tracer quantities of atrial natriuretic factor.
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PMID:Neutral metalloendopeptidase inhibitors as ANF potentiators: sites and mechanisms of action. 183 29

SCH 32615 is a novel inhibitor of the enzyme, neutral endopeptidase (NEP, E.C. 3.4.24.11), the so called 'enkephalinase', which plays a functional role in the degradation of [Met5]- and [Leu5]enkephalin. The present study was designed to assess whether SCH 32615 is able to modify the activity of dopaminergic neurons as reflected by changes in the content of the major dopamine metabolite, dihydroxyphenylacetic acid (DOPAC), in three different areas of the rat brain: the nucleus accumbens, the striatum, and the prefrontal cortex. When administered at analgesically active doses (1-100 mg/kg s.c., 60 min before killing), SCH 32615 induced a dose-dependent increase in dopamine metabolism in the nucleus accumbens but was ineffective in the striatum and in the prefrontal cortex. This effect appears to be mediated via opioid receptors, since it was completely prevented by naloxone (5 mg/kg s.c.). The increase in DOPAC content in the prefrontal cortex elicited by foot-shock was unaffected by pretreatment with SCH 32615. In the nucleus accumbens, dopamine metabolism was increased to the same extent by foot-shock and SCH 32615 administered separately, but these effects were not additive, suggesting that SCH 32615 and foot-shock act via a common mechanism. Taken together, these results support the hypothesis that inhibition of the in vivo degradation of enkephalins induced by the systemic administration of SCH 32615 increases the enkephalinergic tone in the central nervous system and thereby activates the mesolimbic dopaminergic neurons.
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PMID:The neutral endopeptidase-24.11 (enkephalinase) inhibitor, SCH 32615, increases dopamine metabolism in the nucleus accumbens of the rat. 187 83

Hormonal, renal and blood pressure effects of SCH 39370, a selective inhibitor of neutral metalloendopeptidase (endopeptidase 24.11, NEP), were studied in a chronic, congestive heart failure (CHF) model produced by coronary artery ligation in the rat. Sham-operated control rats and rats with CHF were treated either with vehicle or SCH 39370, 30 mg/kg s.c. b.i.d. for 2.5 days. Plasma levels of atrial natriuretic peptide (ANP) and urinary excretion of cyclic GMP (cGMP) were clearly raised in rats with CHF as compared with controls during vehicle treatment. SCH 39370 caused a further increase in plasma ANP in CHF rats but not in control rats. Urinary excretion of immunoreactive ANP and cGMP increased during SCH 39370 treatment both in CHF rats and in controls. SCH 39370 treatment resulted in an initial increase in urine volume in rats with CHF whereas urine sodium excretion did not change significantly. No changes in renal function due to SCH 39370 treatment were seen in control rats. Systolic blood pressure, plasma renin activity and urine excretion of catecholamine metabolites (4-hydroxy-3-methoxyphenyl acetic acid and metanephrines) did not change during SCH 39370 treatment either in controls or in CHF rats. We conclude that the NEP-inhibitory compound SCH 39370 is capable of increasing plasma ANP concentration and urinary excretion of cGMP in rats with chronic CHF. In this severe heart failure model, the possible beneficial effects of additional ANP increments may be blunted, however. NEP inhibitors offer a novel approach to study the significance of ANP elevation in chronic CHF.
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PMID:Elevation of plasma atrial natriuretic peptide in rats with chronic heart failure by SCH 39370, a neutral metalloendopeptidase inhibitor. 214 36

SCH-34826 and thiorphan are inhibitors of the neutral endopeptidase (NEP; E.C. 3.4.24.11;) that cleaves the opiate peptides [Met5]- and [Leu5]enkephalin at the glycinylphenylalanine bond. These compounds were evaluated for their ability to affect the levels of [Met5]enkephalin-like immunoreactivity (MELI) in the brain and the spinal cord and the release into the extracellular space under resting and K+-evoked conditions. The results showed that oral administration of SCH-34826 (30-100 mg/kg p.o.) or thiorphan (10-30 mg/kg p.o.) had no effect on tissue levels of MELI. In contrast, both agents caused a dose-dependent increase in both the resting and the K+-evoked levels in spinal perfusates, which reached up to 10 times the control values. These data indicate that tissue (presumably intracellular) stores of [Met5]enkephalin are not affected by NEP inhibition and that it is the extracellular effects of the peptide that are potentiated by enzyme blockade. This agrees with the prior results demonstrating that NEP inhibitors require a nociceptive stimulus sufficient to release endogenous stores of [Met5]enkephalins for their actions to be observed.
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PMID:Studies on the effect of SCH-34826 and thiorphan on [Met5]enkephalin levels and release in rat spinal cord. 280 77

The effects of enzyme inhibitors on vasoactive intestinal peptide (VIP)-induced decreases in airway opening pressure (PaO) and VIP-like immunoreactivity (VIP-LI) recovery were studied in isolated tracheal superfused guinea pig lungs. In the absence of inhibitors, VIP 0.38 (95% CI 0.33-0.54) nmol/kg animal, resulted in a 50% decrease in PaO and 33% of a 1 nmol/kg VIP dose was recovered as intact VIP. In the presence of two combinations of enzyme inhibitors, SCH 32615 (S, 10 microM) and aprotinin (A, 500 tyrpsin inhibitor units [TIU]/kg) or S and soybean trypsin inhibitor (T, 500 TIU/kg), VIP caused a significantly greater decrease in PaO and greater quantities of VIP were recovered from lung effluent (both P < 0.001). The addition of captopril, (3 microM), leupeptin (4 microM), or bestatin (1 microM) failed to further increase pulmonary relaxation or recovery of VIP-LI. When given singly, A, T, and S did not augment the effects or recovery of VIP. The efficacy of S (a specific inhibitor of neutral endopeptidase [NEP]) and A and T (serine protease inhibitors) thus implicated NEP and at least one serine protease as primary modulators of VIP activity in the guinea pig lung. We sought to corroborate this finding by characterizing the predominant amino acid sites at which VIP is hydrolized in the lung. When [mono(125I)iodo-Tyr10]VIP was offered to the lung, in the presence and absence of the active inhibitors, cleavage products consistent with activity by NEP and a tryptic enzyme were recovered. These data demonstrate that NEP and a peptidase with an inhibitor profile and cleavage pattern compatible with a tryptic enzyme inactivate VIP in a physiologically competitive manner.
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PMID:Peptidase modulation of vasoactive intestinal peptide pulmonary relaxation in tracheal superfused guinea pig lungs. 767 3

We stably expressed the rat D1A dopamine receptor in mouse fibroblast LTK- cells and obtained specific ligand binding and functional activity characteristic of the D1A dopamine receptor coupled to stimulation of adenylyl cyclase. In the transfected cells, the selective D1 agonist fenoldopam caused a concentration-dependent inhibition of Na+/K(+)-ATPase activity, achieving maximum inhibition of approximately 30%. The latter was abolished by the selective D1 antagonist (+)-SCH 23390 and by the specific protein kinase A inhibitor protein kinase inhibitor-(6-22) amide. In the nontransfected cells, fenoldopam did not affect Na+/K(+)-ATPase activity. 8-Chlorophenylthio-cAMP inhibited Na+/K(+)-ATPase activity in both transfected and nontransfected cells; this effect was blocked by protein kinase inhibitor-(6-22). These results indicate that the inhibition of Na+/K(+)-ATPase activity induced by agonist occupancy of D1A receptors is mediated by protein kinase A.
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PMID:D1A dopamine receptor stimulation inhibits Na+/K(+)-ATPase activity through protein kinase A. 809 27

We have synthesized several derivative of dl-threo-methylphenidate (Ritalin) bearing substituents on the phenyl ring. IC50 values for binding these compounds to rat brain monoamine transporters were assessed using [3H]WIN 35,428 (striatal membranes, dopamine transporters, DAT), [3H]nisoxetine (frontal cortex membranes, norepinephrine transporters, NET) and [3H]paroxetine (brain stem membranes, 5HT transporters, 5HTT). Affinities (1/Ki) decreased in the order: DAT > NET >> 5HTT. Substitution at the para position of dl-threo-methylphenidate generally led to retained or increased affinity for the dopamine transporter (bromo > iodo > methoxy > hydroxy). Substitution at the meta position also increased affinity for the DAT (m-bromo > methylphenidate; m-iodo-p-hydroxy > p-hydroxy). Substitution at the ortho position with bromine considerably decreased affinity. Similar IC50 values for binding of o-bromomethylphenidate to the dopamine transporter were measured at 0, 22 and 37 degrees. N-Methylation of the piperidine ring of methylphenidate also considerably reduced affinity. The dl-erythro isomer of o-bromomethylphenidate did not bind to the DAT (IC50 > 50,000 nM). Affinities at the dopamine and norepinephrine transporters for substituted methylphenidate derivatives were well correlated (r2=0.90). Abilities of several methylphenidate derivatives to inhibit [3H]dopamine uptake in striatal synaptosomes corresponded well with inhibition of [3H]WIN 35, 428 binding. None of the compounds examined exhibited significant affinity to dopamine D1 or D2 receptors (IC50 > 500 or 5,000 nM, respectively), as assessed by inhibition of binding of [3H]SCH 23390 or [123I]epidepride, respectively, to striatal membranes.
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PMID:Affinities of methylphenidate derivatives for dopamine, norepinephrine and serotonin transporters. 878 5

1. The role of the metalloendopeptidase EC 3.4.24.15 (EP 24.15) in peptide metabolism in vivo is unknown, in part reflecting the lack of a stable enzyme inhibitor. The most commonly used inhibitor, N-[1-(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Tyr-p-aminobenzoate (cFP-AAY-pAB, Ki = 16 nM), although selective in vitro, is rapidly degraded in the circulation to cFP-Ala-Ala, an angiotensin converting enzyme (ACE) inhibitor. This metabolite is thought to be generated by neutral endopeptidase (NEP; EC 3.4.24.11), as the Ala-Tyr bond of cFP-AAY-pAB is cleaved by NEP in vitro. In the present study, we have examined the role of NEP in the metabolism of cFP-AAY-pAB in vivo, and have tested a series of inhibitor analogues, substituted at the second alanine, for both potency and stability relative to the parent compound. 2. Analogues were screened for inhibition of fluorescent substrate cleavage by recombinant rat testes EP 24.15. D-Ala or Asp substitution abolished inhibitory activity, while Val-, Ser- and Leu-substituted analogues retained activity, albeit at a reduced potency. A relative potency order of Ala (1) > Val (0.3) > Ser (0.16) > Leu (0.06) was observed. Resistance to cleavage by NEP was assessed by incubation of the analogues with rabbit kidney membranes. The parent compound was readily degraded, but the analogues were twice (Ser) and greater than 10 fold (Leu and Val) more resistant to cleavage. 3. Metabolism of cFP-AAY-pAB and the Val-substituted analogue was also examined in conscious rabbits. A bolus injection of cFP-AAY-pAB (5 mg kg-1, i.v.) significantly reduced the blood pressure response to angiotensin I, indicating ACE inhibition. Pretreatment with NEP inhibitors, SCH 39370 or phosphoramidon, slowed the loss of cFP-AAY-pAB from the plasma, but did not prevent inhibition of ACE. Injection of 1 mg kg-1 inhibitor resulted in plasma concentrations at 10 s of 23.5 microM (cFP-AAY-pAB) and 18.0 microM (cFP-AVY-pAB), which fell 100 fold over 5 min. Co-injection of 125I-labelled inhibitor revealed that 80-85% of the radioactivity had disappeared from the circulation within 5 min, and h.p.l.c. analysis demonstrated that only 25-30% of the radiolabel remained as intact inhibitor at this time. Both analogues were cleared from the circulation at the same rate, and both inhibitors blunted the pressor response to angiotensin I, indicative of ACE inhibition. 4. These results suggest that both NEP and other clearance/degradation mechanisms severely limit the usefulness of peptide-based inhibitors such as cFP-AAY-pAB. To examine further EP 24.15 function in vivo, more stable inhibitors, preferably non-peptide, must be developed, for which these peptide-based inhibitors may serve as useful molecular templates.
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PMID:Synthetic inhibitors of endopeptidase EC 3.4.24.15: potency and stability in vitro and in vivo. 881 53


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