Objective: Hypertension is a cardiometabolic disorder characterized by high blood pressure and structural and functional changes in skeletal muscle. Beyond its mechanical role, skeletal muscle functions as an endocrine organ, releasing myokines such as apelin, which influence vascular tone, metabolism, and blood pressure regulation. Impaired apelin signaling has been linked to hypertension. Exercise is a well-established non-drug strategy to reduce blood pressure and improve muscle health. This study aimed to investigate the impact of treadmill training on blood pressure, skeletal muscle apelin levels, and relative heart and muscle masses in spontaneously hypertensive rats Design and method: The study was approved by the Local Ethics Committee for Animal Studies in Poznan (approval no. 62/2023). Sixteen spontaneously hypertensive rats (SHRs) were randomly assigned to a trained (SHR-T, n=8) or non-trained (SHR-NT, n=8) group. SHR-T rats underwent a 12-week treadmill training protocol (10 m/min, 5° incline, 10 min/day, 5 days/week) while receiving a standard AIN-93 M diet. Body mass and blood pressure were measured prior to euthanasia, with blood pressure assessed using the CODA system (Kent Scientific Corporation). After euthanasia, the heart and musculus rectus femoris were collected and stored at -80°C. Apelin concentrations were measured in skeletal muscle homogenates using ELISA (Qayee Biochemicals; Shanghai, China). Statistical analyses were performed using IBM SPSS Statistics 29 and Python. Results: Both systolic (SYS) and diastolic (DIA) BP were significantly lower in the SHR-T group compared to the SHR-NT group, after 12-weeks training (SYS: p=0.002, DIA: p=0.003). Relative heart mass was significantly higher in the SHRT group than in SHRNT rats (p = 0.021), while relative skeletal muscle mass did not differ between groups. Skeletal muscle apelin levels were significantly higher in the SHR-NT group than in the SHR-T group (p = 0.021). Conclusions: Twelve weeks of treadmill training significantly reduced SYS and DIA blood pressure in SHRs. The parallel reduction in skeletal muscle apelin levels and increase in relative heart mass suggest that exercise-induced blood pressure lowering may involve modulation of muscle–heart crosstalk in hypertension. However, this issue needs further investigation.
Selvan et al. (Fri,) studied this question.