• Open Access

The Cardiac Biomarker Sodium-Calcium Exchanger (NCX-1) Can Differentiate between Heart Failure and Renal Failure: A Comparative Study of NCX-1 Expression in Dogs with Chronic Mitral Valvular Insufficiency and Azotemia


Corresponding author: Dr Changbaig Hyun, The Section of Small Animal Internal Medicine, School of Veterinary Medicine, Institute of Veterinary Medicine, Kangwon National University, Chuncheon 201-100, South Korea; e-mail: hyun5188@kangwon.ac.kr.


Background: The sodium-calcium exchanger (NCX-1), an established cardiac biomarker, was postulated previously as differentiating between heart failure (HF) and renal failure (RF) in dogs. The effect of azotemia on NCX-1 expression has not been studied.

Hypothesis: In contrast to other cardiac biomarkers (eg, N-terminal-proBNP), we hypothesized that the expression level of NCX-1 is not influenced by either azotemia or decreased renal clearance.

Animals: Fifteen client-owned healthy control dogs, 14 dogs with chronic mitral valvular insufficiency (CMVI), classified based on severity of the disease by the established International Small Animal Cardiac Health Council classification system, and 15 dogs with RF, grouped according to the International Renal Interest Society stage classification.

Methods: A comparative study of the expression levels of NCX-1, evaluated in peripheral blood samples from dogs with HF, RF, and healthy controls by quantitative PCR.

Results: NCX-1 expression was significantly increased in moderate (2.99 ± 0.61 [fold changes relative to normal group]) to severe (4.35 ± 1.44) CMVI dogs (P < .01). In contrast, NCX-1 expression was not increased in the azotemic dogs. Furthermore, there was also no correlation between increased concentrations of creatinine and urea nitrogen in serum and NCX-1 expression in the RF group.

Conclusions and Clinical Importance: Azotemia likely does not affect NCX-1 expression.