High-intensity interval training does not affect the expression of endothelial genes in spontaneously hypertensive rat

Objective: Hypertension and the aging process result in changes to the endothelial-related muscular system that may negatively impact exercise capacity. Research has shown that high-intensity interval training(HIIT) may be beneficial for individuals with hypertension.However, there are currently no studies that compare the effects of this type of exercise on endothelial markers in the skeletal muscles of aging rats.In order to examine the effects of HIIT on muscular microcirculation markers in hypertension, we assessed the genes encoding proteins related to vasomotor function (NOS3 and ET-1) and angiogenesis (VEGF and PIK3R2) in the soleus and diaphragm muscles of old spontaneously hypertensive rats. To corroborate our results, we analyzed the expression of these genes in samples from individuals who participated in HIIT for 6 weeks (GSE 109657). Design and method: Male 12-month-old spontaneously hypertensive rats were randomly assigned to either a sedentary group (n=10) or a high-intensity interval training (HIIT) group (n=10). The HIIT group underwent training on a rodent treadmill for 50 minutes per day, five times per week, for a period of eight weeks. Systolic blood pressure (SBP), functional capacity, and expression of endothelial gene-encoding proteins associated with NOS3, ET-1, VEGF, and PIK3R2 were analyzed. We retrieved a transcriptomic dataset (GSE109657) of human muscle biopsies collected from the vastus lateralis pre- and post-HIIT (a total of 22 samples, 11 pre-HIIT and 11 post-HIIT) for differential expression analysis. The relative expressions of NOS3, PIK3R2, VEGF were displayed through a heatmap using the MORPHEUS tool. In this dataset, ET-1 expression was not detected thus, we only represented the ET-2 transcriptional variant in the heatmap Results: Our findings indicated that that 8-week of HIIT led to a statistically significant reduction in SBP (p=0.001) and improvement in functional capacity (p<0.001) without affecting the expression of NOS3, PIK3R2, VEGF, or ET-1 in the soleus and diaphragm muscles. Additionally, our reanalysis of vastus lateralis muscle biopsy revealed no differences in the genes of interest, corroborating our results. Conclusions: These findings suggest that 8-week of HIIT may promote decreased arterial pressure and enhanced physical condition without interfering with the expression of mRNA-encoding vasomotor and angiogenic factors in different skeletal muscles.