Used in biomedical research to quantify apelin protein levels in biological samples such as serum, plasma, and cell culture supernatants. Enables investigation of apelin's role in cardiovascular function, angiogenesis, and energy metabolism. Widely applied in studies related to heart failure, hypertension, diabetes, and obesity. Supports drug development and validation by monitoring apelin expression changes in response to therapeutic interventions. Provides a reliable, sensitive, and specific method for high-throughput screening in both clinical and preclinical settings.