Effects of Age, Sex, and Exercise on Measurement of Serum CTnI Levels and Some Parameters Related to the Cardiovascular Capacity of Caspian Horses

Due to their high specificity and exclusive cardiac myocyte sensitivity, cardiac troponins T and I (cTnT, cTnI) are currently regarded as ideal biomarkers to identify cardiomyocyte damage, myocardial injury, myocardial infarction, and chronic heart failure. In fact, cTnI is considered the most reliable biomarker for diagnosing heart-related issues. This study aimed to investigate the effects of age, gender, and exercise training on serum cTnI levels and various parameters related to the cardiovascular capacity of Caspian horses. For this purpose, 50 adult Caspian horses over 3 years old, both male and female, were selected from horse breeding centres and clubs in the provinces of Tehran, Alborz, and Gilan. To account for age-related differences, the horses were divided into three groups: Group A (less than 5 years), Group B (between 5 and 10 years), and Group C (over 10 years). To measure cTnI levels, 10 mL of blood was collected from the jugular vein of each horse using a venoject blood collection tube before exercise and another 10 mL 2 h post-exercise. The samples were refrigerated and centrifuged for 30 min after collection. Two millilitres of serum obtained from each horse at both time points was stored at -20°C for subsequent analysis. Troponin I levels were measured in the laboratory using the electrochemical luminescence (ECL) method. The results of this study reveal for the first time that the normal average of serum cTnI, packed cell volume (PCV), and blood haemoglobin (Hb) levels in Caspian horses is 2.5 ng/L, 35.52%, and 12.1%, respectively. Furthermore, the findings indicate that exercise significantly increases serum levels of cTnI, PCV, and blood haemoglobin; however, age and gender did not appear to affect these measured parameters. Therefore, it can be concluded that exercise stimulates the release of troponin due to myocardial injury.