Corin is a transmembrane protease, which is expressed primarily in cardiomyocytes, where it converts the inactive proatrial natriuretic peptide (proANP) and probrain natriuretic peptide (proBNP) into active peptides.

Enzyme-linked immunosorbent assays (ELISA) have been used to measure both corin and N-terminal proANP (NT-proANP) concentrations in plasma samples of patients with different manifestations of atrial fibrillation (AF) and suitable controls.

Cardiologists at the First Affiliated Hospital of Dalian Medical University (China) recruited a total of 268 subjects, including 141 AF patients; 83 with paroxysmal AF, 58 with persistent AF and 127 controls. Paroxysmal AF (PAF) was defined as AF episodes lasting less than seven days and which terminated spontaneously. Persistent AF (PeAF) was defined as AF episodes lasting more than seven days and/or requiring termination with pharmacologic or direct current cardioversion.

An ELISA kit (R&D Systems; Minneapolis, MN, USA) was used to measure corin concentrations in the study. After the reaction the optical density (OD) in the wells was recorded by a spectrometer microplate reader (BioTek; Winooski, VT, USA) with the absorbance wavelength at 450 nm and correction at 570 nm within 20 minutes. An ELISA kit (Biomedica; Vienna, Austria) was used to measure NT-proANP concentrations and the OD was measured within 20 minutes by the spectrometer at 450 nm.

Plasma corin concentrations in patients with AF and PeAF were 1,209 ± 510 pg/mL and 1,377 ± 548 pg/mL, respectively, which were significantly higher than those in controls at 973 ± 528 pg/mL. However, the difference between the PAF patients and controls was not statistically significant at 1,092 ± 448 pg/mL versus 973 ± 528 pg/mL. The difference between the two patient groups was significant, 1,092 ± 448 pg/mL versus 1,377 ± 548 pg/mL. The concentrations in male controls were significantly higher than that in the female controls 1,120 ± 577 pg/mL versus 713 ± 281 pg/mL, and in male patients, the plasma corin concentrations were also higher than that in female patients, 1,365 ± 485 pg/mL versus 842 ± 358 pg/mL.

The authors concluded that high plasma corin concentrations in patients with AF suggests that corin may play an important role in the pathology of AF and that plasma corin, like proANP and ANP, may be a useful biomarker for AF, although no correlation was found between plasma corin and NT-proANP concentrations both in controls and in cases. The study was published on July 20, 2015, in the journal Clinica Chimica Acta.

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First Affiliated Hospital of Dalian Medical University 
R&D Systems 
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