Effect of the renal natriuretic peptide, ularitide, alone or combined with Vasopeptidase inhibitor, Omapatrilat, on experimental volume overloadinduced congestive heart failure in rats (Ularitide/ Omapatrilat in Congestive Heart Failure)

Abstract

Introduction: Ularitide is a synthetic form of renally derived natriuretic peptide (NP), urodilatin. Omapatrilat (OMA) is a Vasopeptidase inhibitor (VPI), acting by dual inhibition of both angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP), which degrades the NPs. Ularitide and OMA underwent evaluation for the management of hypertension and heart failure (HF).

Aim: This study aimed to address the effect of ularitide and OMA in aortocaval fistula (ACF) – induced congestive heart failure (CHF) in rats under various conditions of compensation (of clinical severity).

Experimental protocol: Volume-overload CHF was induced in male albino rats by creating an infrarenal ACF. One week after fistula induction, ACF rats were randomized to compensated (Com) and decompensated (Decom) ACF groups and each further subdivided into ACF, ularitide and OMA/ularitide treated ACF groups. Sham was used as control. All treatment protocols were started one week after infrarenal ACF induction and continued for further two weeks. Three weeks after shunt induction, all animals were underwent assessment of cardiorenal and humoral functions. Renal outcome was measured by glomerular filtration rate (GFR), fractional excretion of sodium (F_Na), absolute urinary sodium excretion (U_NaV), urine volume, plasma cystin C level and urinary cyclic 30, 50-guanosine monophosphate (cGMP). The humoral function was assessed by plasma renin activity (PRA), angiotensin II (Ang II), Aldosterone, and cGMP. Cardiac outcome was assessed by plasma atrial natriuretic peptide (ANP), N-terminal pro–brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) while total and relative heart, lung and liver weights were recorded.

Results: Induction of AC shunt was associated with deteriorated renal and excretory functions, activation of renin angiotensin aldosterone system (RAAS), elevated ANP with renal resistance to ANP, (NT-proBNP) and (cTnT), pulmonary and systemic congestion and marked cardiac hypertrophy. These changes were exacerbated in Decom-ACF. Ularitide treatment of ACF rats was associated with natriuresis, diuresis, enhanced GFR with RAAS inhibition. This effect was evident in Com-ACF, maximized by OMA but attenuated in Decom-ACF, restored by OMA treatment. Ularitide/OMA treatment had antihypertrophic, decongestant effect with preserved renal function, resulted in a marked improvement of animals’ survival.

Conclusion: OMA potentiates the cardiorenal actions of ularitide in ACF-induced Com CHF and restoring its effect in Decom ACF, by simultaneously inhibiting ACE and NEP. OMA and ularitide could provide an effective therapeutic strategy for CHF.

Keywords: Congestive heart failure; Aorto-caval fistula; Ularitide; Omapatrilat; Renin-angiotensin system; Vasopeptidase inhibition