A process for screening for a ligand molecule that possesses an agonist biological activity on the NEP binding site for an SMR1 peptide, such as the QHNPR (SEQ ID NO: 2) pentapeptide. The method comprises preparing a cell culture or preparing an organ specimen or a tissue sample containing NEP binding sites for an SMR1 peptide, incubating the cell culture, organ specimen or tissue sample of at concentrations allowing measurement of NEP enzymatic activity under initial velocity conditions in the presence of a candidate ligand molecule, a half-saturating concentration of an SMR1 peptide, and a NEP substrate during a time sufficient for the hydrolysis activity of the NEP substrate to take place under initial velocity conditions; and quantifying the activity of the NEP present in the biological material of by measuring the levels of NEP substrate hydrolysis, respectively in the presence or in the absence of the ligand molecule and in the presence or in the absence of the SMR1 peptide.