Beneficial renal and cardiac effects of vasopeptidase inhibition with S21402 in heart failure

Novel O-[11C]-methylated derivatives of the neprilysin inhibitor sacubitril: Radiosynthesis, autoradiography and plasma stability evaluation

INTRODUCTION

The O-[¹¹C]methylated derivatives of the clinically used neprilysin inhibitor (NEPi) sacubitril ([¹¹C]SacOMe, (2R,4S)-ethyl 5-([biphenyl]-4-yl)-4-(4-[¹¹C]methoxy-4-oxobutanamido)-2-methylpentanoate) and LBQ657 ([¹¹C]MeOLBQ, (2R,4S)-5-(biphenyl-4-yl)-4-[(3-carboxypropionyl)amino]-2-methylpentanoic acid [¹¹C]methyl ester and [¹¹C]LBQOMe, (2R,4S)-5-(biphenyl-4-yl)-4-[(4-[¹¹C]methoxy-4-oxobutanamido)]-2-methylpentanoic acid) were evaluated to determine their potential as PET imaging tracers and investigate the effect of such labeling esterification on neprilysin (NEP) binding.

METHODS

[¹¹C]MeOLBQ, [¹¹C]SacOMe and [¹¹C]LBQOMe were synthesized by O-[¹¹C]methylation using [¹¹C]methyl triflate. Binding of these radiolabeled derivatives (5 nM) were assessed by autoradiography on rat neprilysin rich kidney slices with or without 10 μM NEPi (thiorphan or sacubitril) for 20 min at 37 °C. [¹¹C]LBQOMe was further tested for binding selectivity in the presence of 10 μM of angiotensin-converting enzyme inhibitor (ACEi, captopril) or angiotensin II AT₁ receptor blocker (AT1R, losartan). Radioligands were evaluated for their in vitro stability up to 20 min after incubation at 37 °C in rat and human plasma by reverse-phase column-switch HPLC. Non-radioactive SacOMe incubated in rat and human plasma was analyzed by HPLC-coupled with high resolution mass spectrometry (HRMS) to confirm the metabolites' identity. [¹¹C]SacOMe main labeled metabolite was further analyzed by HPLC after incubation in rat kidney slices at 37 °C.

RESULTS

The novel [¹¹C]SacOMe and [¹¹C]LBQOMe were produced in 32 ± 3% RCY and 15 ± 6% at EOS (decay-corrected from [¹¹C]CO₂, n = 3), high molar activity (407 ± 92 GBq/μmol and 260 ± 92 GBq/μmol), and high chemical (≥90%) and radiochemical (≥99%) purities in a total synthesis time of 31 and 34 min, respectively. High accumulation of [¹¹C]SacOMe and [¹¹C]LBQOMe in kidneys was completely blocked (>99.9%) by pre-incubation with NEPi, whereas [¹¹C]MeOLBQ displayed negligible uptake in autoradiography studies. [¹¹C]LBQOMe binding was not affected by saturating doses of losartan or captopril indicating binding selectivity for NEP. While [¹¹C]SacOMe and [¹¹C]LBQOMe were stable in human plasma (>92%) even after 20 min incubation at 37 °C, rat plasma analyses exhibited >95% biotransformation of [¹¹C]SacOMe, 40% of [¹¹C]LBQOMe and >80% loss of the ¹¹C-methyl group of [¹¹C]MeOLBQ after 5 min of incubation. Comparable results using the non-radioactive SacOMe were obtained by HPLC-HRMS. Radio-HPLC analysis of the extracted activity of rat kidney slices incubated with [¹¹C]SacOMe demonstrated that >95% of the radioactive signal corresponded to [¹¹C]LBQOMe as the main metabolite.

CONCLUSION

The desethyl active metabolite of [¹¹C]SacOMe, [¹¹C]LBQOMe, displayed stability in human plasma, binding selectivity for neprilysin over ACE or AT1R in rat kidney slices. Rapid plasmatic dealkylation at the 2-methylbutanoic acid position is in line with the necessity of incorporating the labeling group on oxobutanoic acid side in the strategy to develop a stable O-alkylated labeled derivative of sacubitril.

Development of a new procedure for the determination of captopril in pharmaceutical formulations employing chemiluminescence and a multicommuted flow analysis approach

This paper describes a new technique for the determination of captopril in pharmaceutical formulations, implemented by employing multicommuted flow analysis. The analytical procedure was based on the reaction between hypochlorite and captopril. The remaining hypochlorite oxidized luminol that generated electromagnetic radiation detected using a homemade luminometer. To the best of our knowledge, this is the first time that this reaction has been exploited for the determination of captopril in pharmaceutical products, offering a clean analytical procedure with minimal reagent usage. The effectiveness of the proposed procedure was confirmed by analyzing a set of pharmaceutical formulations. Application of the paired t-test showed that there was no significant difference between the data sets at a 95% confidence level. The useful features of the new analytical procedure included a linear response for captopril concentrations in the range 20.0-150.0 µmol/L (r = 0.997), a limit of detection (3σ) of 2.0 µmol/L, a sample throughput of 164 determinations per hour, reagent consumption of 9 µg luminol and 42 µg hypochlorite per determination and generation of 0.63 mL of waste. A relative standard deviation of 1% (n = 6) for a standard solution containing 80 µmol/L captopril was also obtained.

Natriuretic and renoprotective effect of chronic oral neutral endopeptidase inhibition in acute renal failure

Neutral endopeptidase (NEP: EC 3.4.24.11) is involved in the degradation of peptides such as atrial natriuretic peptide, angiotensin II (AngII), and endothelin-1 (ET-1). In this study we propose that NEP inhibition provides protection in glycerol-induced acute renal failure (ARF). Renal vascular responses were evaluated in ARF rats where ARF was induced by injecting 50% glycerol in candoxatril, a NEP inhibitor (30 mg/kg, orally; for 3 weeks) pretreated rats. AngII and U46619 (a TxA2 mimetic) vasoconstriction was increased (2- to 4-fold) in ARF while ET-1 vasoconstriction was surprisingly reduced (23+/-3%; p<0.05). In ARF, candoxatril paradoxically enhanced ET-1 response (60+/-20%; p<0.05) but reduced AngII vasoconstriction (51+/-11%; p<0.05) without affecting U46619 response. However, candoxatril treatment was without effect on plasma ET-1 and TxB2 levels in ARF. Candoxatril reduced plasma AngII by 34+/-4% (p<0.05) in ARF which was approximately 3.5-fold higher compared to control. Candoxatril doubled the nitrite excretion in control but was without effect on proteinuria or nitrite excretion in ARF. Candoxatril enhanced Na+ and creatinine excretion in ARF by 73+/-9% and 33+/-2%, respectively. These results suggest that NEP inhibition may confer protection in glycerol-induced ARF by stimulating renal function but without a consistent effect on renal production and renal vascular responses to endogenous vasoconstrictors.

Connective tissue growth factor and cardiac fibrosis after myocardial infarction

The temporal and spatial expression of transforming growth factor (TGF)-beta(1) and connective tissue growth factor (CTGF) was assessed in the left ventricle of a myocardial infarction (MI) model of injury with and without angiotensin-converting enzyme (ACE) inhibition. Coronary artery ligated rats were killed 1, 3, 7, 28, and 180 days after MI. TGF-beta(1), CTGF, and procollagen alpha1(I) mRNA were localized by in situ hybridization, and TGF-beta(1) and CTGF protein levels by immunohistochemistry. Collagen protein was measured using picrosirius red staining. In a separate group, rats were treated for 6 months with an ACE inhibitor. There were temporal and regional differences in the expression of TGF-beta(1), CTGF, and collagen after MI. Procollagen alpha1(I) mRNA expression increased in the border zone and scar peaking 1 week after MI, whereas collagen protein increased in all areas of the heart over the 180 days. Expression of TGF-beta(1) mRNA and protein showed major increases in the border zone and scar peaking 1 week after MI. The major increases in CTGF mRNA and protein occurred in the viable myocardium at 180 days after MI. Long-term ACE inhibition reduced left ventricular mass and decreased fibrosis in the viable myocardium, but had no effect on cardiac TGF-beta(1) or CTGF. TGF-beta(1) is involved in the initial, acute phase of inflammation and repair after MI, whereas CTGF is involved in the ongoing fibrosis of the heart. The antifibrotic benefits of captopril are not mediated through a reduction in CTGF.

Myocardial infarction increases ACE2 expression in rat and humans

AIMS

Angiotensin converting enzyme (ACE) 2 catalyses the cleavage of angiotensin (Ang) I to Ang 1-9 and of Ang II to Ang 1-7. ACE2 deficiency impairs cardiac contractility and upregulates hypoxia-induced genes, suggesting a link with myocardial ischaemia. We studied the expression of ACE2 after myocardial infarction (MI) in the rat as well as in human failing hearts.

METHODS AND RESULTS

Rats were killed at days 1, 3, and 28 after MI, or treated for 4 weeks with the ACE inhibitor ramipril (1 mg/kg). Cardiac gene and protein expression of ACE and ACE2 were assessed by quantitative real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry/activity assays/in vitro autoradiography, respectively. Both ACE (P = 0.022) and ACE2 (P = 0.015) mRNA increased in the border/infarct area compared with the viable area at day 3 after MI. By day 28, increases in ACE (P = 0.005) and ACE2 (P = 0.006) mRNA were also seen in the viable myocardium of MI rats compared with myocardium of control rats. ACE2 protein localized to macrophages, vascular endothelium, smooth muscle, and myocytes. Ramipril attenuated cardiac hypertrophy and inhibited cardiac ACE. In contrast, ramipril had no effect on cardiac ACE2 mRNA, which remained elevated in all areas of the MI rat heart. Immunoreactivity of both ACE and ACE2 increased in failing human hearts.

CONCLUSION

The increase in ACE2 after MI suggests that it plays an important role in the negative modulation of the renin angiotensin system in the generation and degradation of angiotensin peptides after cardiac injury.

Cardiac and renal effects of omapatrilat, a vasopeptidase inhibitor, in rats with experimental congestive heart failure

Omapatrilat (OMP) is a novel mixed inhibitor of angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP), the enzyme that metabolizes natriuretic peptides. Congestive heart failure (CHF) is characterized by excessive sodium retention, attributed to both an excessive effect of angiotensin II and diminished responsiveness to natriuretic peptides. In this study, we examined the acute and chronic renal and cardiac effects of OMP in rats with compensated [urinary sodium excretion (UNaV) > 1,200 microeq/day] and decompensated (UNaV < 100 microeq/day) CHF, induced by a surgical aortocaval fistula (ACF). Bolus injection of OMP (10 mg/kg) to sham controls produced significant diuretic and natriuretic responses [UNaV increased from 0.67 +/- 0.19 to 3.27 +/- 1.35 microeq/min, P < 0.05; fractional sodium excretion (FENa) increased from 0.23 +/- 0.06 to 0.95 +/- 0.34%, P < 0.01] despite a significant decline in blood pressure (BP). Rats with compensated CHF displayed blunted diuresis and natriuresis to this dose of OMP but a significant decrease in BP. However, in rats with decompensated CHF, OMP induced significant natriuresis (FENa increased from 0.18 +/- 0.15 to 0.82 +/- 0.26%, P < 0.05) despite a further decrease in BP (from 90 +/- 9 to 71 +/- 6 mmHg, P < 0.01). Two weeks after ACF, the heart/body weight ratio was significantly greater in rats with CHF than controls (0.51 +/- 0.026 vs. 0.30 +/- 0.004%, P < 0.0001), and UNaV was significantly lower. Immediate or late (1 or 6 days after ACF) OMP treatment in the drinking water (140 mg/l) reduced cardiac hypertrophy to 0.41-0.43% (P < 0.01) and induced natriuresis. These results suggest that OMP improves both sodium balance and cardiac remodeling and might be advantageous to ACE inhibitors for the treatment of decompensated CHF.

Cardiorenal protective effects of vasopeptidase inhibition with omapatrilat in hypertensive transgenic (mREN-2)27 rats

Vasopeptidase inhibitors simultaneously inhibit both angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP). The aim of this study was to determine the cardiorenal effects of the vasopeptidase inhibitor omapatrilat in the transgenic m(Ren-2)27 rat which exhibits fulminant hypertension and severe organ pathology. At 6 weeks of age, male Ren-2 rats were randomized to receive no treatment (N = 10), the ACE inhibitor fosinopril 10 mg/kg/day (N = 10), or omapatrilat 10 mg/kg/day (N = 10) or 40 mg/kg/day (N = 10) by daily gavage for 24 weeks. Various cardiorenal functional and structural parameters were assessed. Compared to controls, all treatment groups reduced hypertension in control Ren-2 rats, with both doses of omapatrilat reducing systolic blood pressure significantly more than fosinopril (control, 178 +/- 3 mmHg; fosinopril 10 mg/kg/day, 130 +/- 4 mmHg; omapatrilat 10 mg/kg/day, 110 +/- 3 mmHg; omapatrilat 40 mg/kg/day, 91 +/- 3 mmHg). Omapatrilat dose-dependently reduced cardiac hypertrophy, caused a greater inhibition of renal ACE than fosinopril, and was the only treatment to inhibit renal NEP. Attenuation of albuminuria, glomerulosclerosis and cardiorenal fibrosis occurred to a similar degree with omapatrilat and fosinopril. Omapatrilat confers cardiorenal protection in the hypertensive Ren-2 rat. Although inhibition of tissue NEP may contribute to the superior blood pressure reduction by omapatrilat, overall, the results are consistent with the central role that angiotensin II plays in renal and cardiac fibrosis in this model of hypertension.

Chronic endopeptidase inhibition in DOCA-salt hypertension: mechanism of cardiovascular protection

These studies examined the interactions of neutral endopeptidase (NEP), endothelin-1 (ET-1), and nitric oxide (NO) in deoxycorticosterone acetate (DOCA)-induced hypertension. Male Sprague-Dawley rats (n = 35) were uninephrectomized (UNx) or uninephrectomized and treated with DOCA (25 mg pellet implanted subcutaneously). Candoxatril (30 mg/kg day(-1)), a NEP inhibitor, was given orally for 3 weeks in UNx or DOCA rats. Sham nephrectomized rats (SHAM) served as controls. Except SHAM, all other groups received 1% NaCl in drinking water ad libitum. Measurements were taken of systolic blood pressure (SBP), left ventricle (LV), and aortic weight (AW), plasma ET-1, and urinary excretion of nitrite and Na+. Whole body vascular hypertrophy and morphometric analysis of histological sections of the heart were also determined. In DOCA rats, SBP increased from 113 +/- 5 to 170 +/- 5 mmHg without significant changes in body weight (BW). Candoxatril reduced the increase in SBP to 135 +/- 9 mmHg (P < 0.05), abolished the increased LV wall thickness (P < 0.05), and increased the reduced LV lumen diameter (P < 0.05) in DOCA-salt rats. Candoxatril also reduced plasma ET-1 by 88 +/- 9% and 89 +/- 17% (P < 0.05) in UNx and DOCA rats, respectively, and elicited increases in urinary excretion of nitrite. These effects were accompanied by a marked increase in urinary excretion of Na+ (U(Na)V) (P < 0.05) and a blunting of the proteinuria (32 +/- 5%; P < 0.05) in DOCA rats. We conclude that endopeptidase inhibition in DOCA-salt hypertension reduced the increase in blood pressure and the attendant tissue hypertrophy and renal injury. These effects suggest a correlation between endopeptidase-related reduction in ET-1 production and protection in DOCA-salt hypertension.

Upregulation of cardiac insulin-like growth factor-I receptor by ACE inhibition after myocardial infarction: potential role in remodeling

This study evaluated the effects of angiotensin-converting enzyme (ACE) inhibition after myocardial infarction (MI) on cardiac remodeling and gene expression and localization of components (ligands, receptors, and binding proteins) of the cardiac insulin-like growth factor (IGF) system. After ligation of the coronary artery, rats were randomized to vehicle or ACE inhibitor (Captopril, 50 mg/kg/day) for 4 weeks. Blood pressure, cardiac remodeling, and components of the IGF system were localized in the heart using in situ hybridization (ISH) and immunohistochemistry (IHC). The average infarct size was 42%. There were regional differences in the expression of the IGF system after MI, with increased IGF-I mRNA abundance in the border (24-fold) and infarct (12-fold) and increased IGF-binding protein (IGFBP)-3 mRNA in all areas of the failing left ventricle (threefold). Captopril reduced blood pressure, attenuated cardiac remodeling, and caused a threefold increase in IGF-I receptor mRNA and protein in infarct, border zone, and viable myocardium (p<0.01). Captopril had no effect on IGF-I mRNA but further increased IGFBP-3 mRNA and protein in the border zone, (p<0.05). The changes in the cardiac IGF system following MI are highly localized, persist for at least 4 weeks, and can be modulated by ACE inhibition. These data suggest that the benefits of ACE inhibitors in attenuation of cardiac remodeling may be mediated in part through increased expression of the IGF-I receptor sensitizing the myocardium to the positive effects of endogenous IGF-I.

Beneficial effects of sampatrilat, a novel vasopeptidase inhibitor, on cardiac remodeling and function of rats with chronic heart failure following left coronary artery ligation

Sampatrilat is a novel vasopeptidase inhibitor that may offer a greater benefit than traditional angiotensin-converting enzyme (ACE) inhibitors in the treatment of chronic heart failure (CHF). The present study was undertaken to determine whether sampatrilat improves hemodynamic function and cardiac remodeling through a direct action on the failing heart in rats with CHF following left coronary artery ligation (CAL). Sampatrilat (30 mg/kg a day) was administered orally to the animals from the 1st to 6th week after the operation. Sampatrilat reduced the mortality of the rats with CAL (20 versus 57% for untreated rats). Treatment with sampatrilat for 5 weeks suppressed tissue ACE and neutral endopeptidase (NEP) activities. Sampatrilat did not affect the arterial blood pressure, whereas it attenuated the CAL-induced increases in the left ventricular end-diastolic pressure, heart weight, and collagen content of the viable left ventricle. To assess the direct effects of sampatrilat on collagen synthesis, we measured the incorporation of [(3)H]proline into cultured cardiac fibroblasts. Sampatrilat at concentrations that inhibited NEP activity in vitro augmented the atrial natriuretic peptide-induced decrease in [(3)H]proline incorporation by the cells. In addition, sampatrilat prevented the angiotensin I-induced increase in [(3)H]proline incorporation, whereas captopril did not. The results suggest that long-term treatment with sampatrilat regresses cardiac remodeling in rats with CAL, which is associated with improvement of hemodynamic function. The mechanism by which sampatrilat improved cardiac remodeling may be attributable to the direct inhibition of cardiac fibrosis, possibly acting through the cardiac natriuretic peptide system.

Renoprotective effects of VPI versus ACEI in normotensive nephrotic rats on different sodium intakes

BACKGROUND

Control of blood pressure (BP) and optimal reduction of proteinuria (Uprot) are necessary for long-term renoprotection. Unfortunately, angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II (Ang II) antagonists are not effective during sodium repletion. Vasopeptidase inhibitors (VPI) cause dual inhibition of ACE and neutral endopeptidase, the latter resulting in decreased atrial natriuretic peptide (ANP) breakdown and thus enhanced natriuresis. Therefore, in contrast with ACEI, VPI may be effective during high sodium intake.

METHODS

To test this hypothesis, the renoprotective actions of the new VPI gemopatrilat (GEM) were studied during low (0.05% NaCl) and high (3.0% NaCl) sodium diets in normotensive Wistar rats with established adriamycin nephrosis. The ACEI lisinopril (LIS) was used as control. Rats received either GEM (0.3 mg/g chow), an equihypotensive dose of LIS (75 mg/L drinking water), or vehicle (VEH) from week 6 (that is, established Uprot) until sacrifice. The effect of therapy was monitored by measuring systolic BP and Uprot (weekly) and structural renal damage at the end of study (week 16).

RESULTS

During low sodium, GEM effectively reduced Uprot (-48 +/- 4%), but LIS was more effective (-80 +/- 2%), while Uprot slightly increased in VEH (+23 +/- 2%). The focal glomerulosclerosis (FGS) score after GEM (38 +/- 14) was lower than in the VEH group (79 +/- 27), although this was not significant. LIS (18 +/- 6) reduced FGS significantly. Remarkably, on high sodium, GEM was completely ineffective in reducing BP, Uprot and structural renal injury, just like LIS.

CONCLUSIONS

The renoprotective actions of VPI depend on dietary sodium intake in normotensive nephrotic rats: therapeutic efficacy is fully blunted by a high sodium diet. During a low sodium diet, gemopatrilat was renoprotective, but less effective than lisinopril. Whether higher doses of the VPI could improve its renoprotective efficacy remains to be elucidated.

Up-regulation of components of the renin-angiotensin system in the bile duct-ligated rat liver

BACKGROUND & AIMS

Angiotensin II (ANG II) has profibrotic actions in the heart and kidney, whereas blockade of the renin angiotensin system (RAS) attenuates injury. This study examines whether the RAS is present in the liver and examines its regulation in the bile duct-ligation model of hepatic fibrogenesis.

METHODS

Sham-operated and bile duct-ligated (BDL) Sprague-Dawley rats were studied. Gene and protein expression of hepatic renin, angiotensinogen, angiotensin-converting enzyme (ACE), and the angiotensin receptors AT1 and AT2 were assessed using real-time reverse-transcription polymerase chain reaction, in vitro autoradiography, and immunohistochemistry.

RESULTS

Angiotensinogen and renin messenger RNA were detected in sham liver but were not increased following BDL. Angiotensinogen protein was widely distributed in hepatocytes in both normal and injured livers, but in BDL livers, it was also expressed within areas of active fibrogenesis. Both ACE and AT1 receptor genes were up-regulated following BDL. The low level of ACE activity in sham animals was significantly increased in areas of active fibrogenesis in BDL livers. The AT1 receptor was present in both normal and diseased liver parenchyma, with increased AT1 receptor binding seen in fibrotic areas in the diseased liver. The AT2 receptor gene was not detected in normal or diseased liver.

CONCLUSIONS

Key elements of the RAS are present in normal liver tissue, and there is major up-regulation of the system in the bile duct-ligated liver. These findings are in keeping with recent experimental studies that have demonstrated antifibrotic effects of RAS blockade in the bile duct-ligated liver.

Evidence for cardioprotective, renoprotective, and vasculoprotective effects of vasopeptidase inhibitors in disease

In both the natriuretic peptide and renin-angiotensin systems, peptidases play an important role in the inactivation or activation of the system. Angiotensin-converting enzyme is responsible for the conversion of angiotensin I to angiotensin II, while neutral endopeptidase is one of the pathways involved in the degradation of the natriuretic peptides. The vasopeptidase inhibitors, which simultaneously inhibit neutral endopeptidase and angiotensin-converting enzyme, appear to offer distinct therapeutic advantages in treating hypertension, heart failure, and endothelial dysfunction.

In-vitro and in-vivo inhibition of rat neutral endopeptidase and angiotensin converting enzyme with the vasopeptidase inhibitor gemopatrilat

OBJECTIVES

Vasopeptidase inhibitors are single molecules that simultaneously inhibit neutral endopeptidase (NEP) and angiotensin converting enzyme (ACE). The aim of this study was to characterize in-vitro and in-vivo inhibition of NEP and ACE in the rat with the vasopeptidase inhibitor gemopatrilat.

DESIGN AND METHODS

In-vitro NEP and ACE inhibition was studied by radioinhibitory binding assay using rat renal membranes and the specific NEP inhibitor radioligand 125I-RB104 and the specific ACE inhibitor radioligand 125I-MK351A, respectively (n = 3 per curve). In-vivo NEP and ACE inhibition was studied using in-vitro autoradiography in rats that received oral gemopatrilat (1, 3, 10 mg/kg; n = 4 per dose) and were killed 1 h later, or received oral gemopatrilat (3, 10 mg/kg) and were killed at time points 1, 2, 4, 8, 18, 24 and 48 h (n = 4 per time point).

RESULTS

Gemopatrilat caused a concentration-dependent displacement of specific radioligands from renal membrane NEP (IC50 305 +/- 5.4 nmol/I) and ACE (IC50 3.6 +/- 0.02 nmol/). In the dose-response study gemopatrilat (1, 3 and 10 mg/kg) caused significant inhibition of plasma ACE (P< 0.01), and renal ACE and NEP (3, 10 mg/kg, P < 0.01). In the time course experiment, gemopatrilat (10 mg/kg) increased plasma renin activity for 8 h (P< 0.01) and inhibited plasma ACE (P< 0.05), renal NEP (P< 0.01) and renal ACE (P< 0.05) for 48 h.

CONCLUSIONS

Gemopatrilat is a potent in-vitro vasopeptidase inhibitor that also causes prolonged inhibition of circulating and renal ACE and renal NEP after a single oral dose. The data suggest that gemopatrilat may be a useful addition to existing vasopeptidase inhibitors in the treatment of cardiovascular disease.