Benefits of combined exercise training on arterial stiffness and blood pressure in spontaneously hypertensive rats treated or not with dexamethasone

Aerobic Exercise Practiced Over Time Mitigates the Structural Effects on the Vascular System Caused by the Deleterious Effects of Aging

Background

Aerobic training has been considered beneficial for determining the detrimental alterations in blood vessels caused by aging.

Objective

Evaluate the relationship between the preventive effects of aerobic exercise and time of practice on cardiovascular health, in aged Wistar rats.

Methods

Wistar rats (16 months) were divided into 3 groups: (1) sedentary (AGED); (2) long-term trained\61 weeks (LTT); and (3) short-term trained\final 8 weeks of life (STT). Body weight, maximum physical capacity, systolic blood pressure (SBP), pulse wave velocity (PWV), plasma nitrite (NO), oxidative stress (TBARS), wall thickness, the wall-to-lumen ratio, and collagen of the thoracic aorta, carotid, and femoral arteries were measured.

Results

Both trained groups showed an increase in physical capacity when compared to the AGED group (p=<0.001 for LTT and p=0.011 for STT), and the LTT group demonstrated higher values when compared to the STT group (p= 0.004). The LTT group presented attenuation of PWV (p= 0.002) and a reduction in the wall thickness and wall-to-lumen ratio of the thoracic aorta (p=0.032 and 0.008, respectively) and carotid arteries (p=0.019 and 0.012, respectively) when compared to the AGED group. The STT group presented a reduction in TBARS compared to the AGED group (p=0.046). Additionally, both trained groups (LTT and STT) presented a reduction in the percentage of arterial collagen compared to the AGED group in the thoracic aorta (p=<0.001 and p=0.001 respectively) and carotid arteries (p= <0.008 and p= 0.041 respectively).

Conclusion

This study demonstrated that long-term training decreased the level of collagen, PWV values, wall thickness, and the wall-to-lumen ratio of the aorta and carotid arteries compared to the AGED group. Moreover, short-term training reduced TBARS and collagen percentage in the aorta and carotid arteries compared to the AGED group.

Dexamethasone-Induced Arterial Stiffening Is Attenuated by Training due to a Better Balance Between Aortic Collagen and Elastin Levels

PURPOSE

Although the cardioprotective benefits of exercise training are well known, the effects of training on dexamethasone (DEX)-induced arterial stiffness are still unclear. This study was aimed at investigating the mechanisms induced by training to prevent DEX-induced arterial stiffness.

METHODS

Wistar rats were allocated into 4 groups and submitted to combined training (aerobic and resistance exercises, on alternate days, 60% of maximal capacity, for 74 d) or were kept sedentary: sedentary control rats (SC), DEX-treated sedentary rats (DS), combined training control (CT), and DEX-treated trained rats (DT). During the last 14 d, rats were treated with DEX (50 μg/kg per body weight, per day, s.c.) or saline.

RESULTS

DEX increased PWV (+44% vs +5% m/s, for DS vs SC, p<0.001) and increased aortic COL 3 protein level (+75%) in DS. In addition, PWV was correlated with COL3 levels (r=0.682, p<0.0001). Aortic elastin and COL1 protein levels remained unchanged. On the other hand, the trained and treated groups showed lower PWV values (-27% m/s, p<0.001) vs DS and lower values of aortic and femoral COL3 compared with DS.

CONCLUSION

As DEX is widely used in several situations, the clinical relevance of this study is that the maintenance of good physical capacity throughout life can be crucial to alleviate some of its side effects, such as arterial stiffness.

Physical activity has a stronger correlation with arterial stiffness than strength, balance, or BMI in an older population

Background: Arterial stiffness is associated with an array of debilitating health conditions. While exercise typically has beneficial effects on both arterial stiffness and overall health, more research is needed to understand the associations of different types of fitness indices with arterial stiffness. Aim: To investigate the relationship between balance, strength, cardiovascular fitness and physical activity with arterial stiffness (as measured by pulse wave velocity (PWV)) in older adults. Method: Eighty retirement-village residents (24 males, 56 females, age: 78.2 ± 6.4 years, weight: 69.4 ± 12.5 kg, height: 162.9 ± 8.5 cm) completed the Yale Physical Activity Survey, PWV measurement, 30-s sit-to-stand leg strength test, hand grip strength assessment, 4-stage balance test, and a 6-min walk fitness test. The number of exiting risk factors (smoking, previous heart incidents, previous stroke(s), having hypertension, or taking anti-hypertension medication) were tallied. Pearson's correlations were used to assess the relationship between PWV and health and fitness parameters. Results were interpreted using qualitative inference. Results: The number of risk factors (r = 0.57, p < 0.001), age (r = 0.51, p < 0.001) and systolic blood pressure (r = 0.50, p = 0.001) had strong, harmful associations with PWV. Total physical activity minutes/week (r = -0.31 p = 0.01), total energy expenditure Kcal/week (r = -0.30, p = 0.01), and the 6-min walk test (r = -0.29, p = 0.01) had a moderate, beneficial association with PWV, while sit-to-stand (r = -0.27, p = 0.02) and balance (r = -0.27, p = 0.01) had a weak, beneficial association with PWV. Hand grip strength (r = 0.02, p = 0.94) and body mass index (r = -0.04, p = 0.75) had no significant associations with PWV. Discussion: All measured fitness indices had beneficial associations with PWV. However, having more risk factors, increased age, and higher systolic blood pressure had significant (harmful) associations with PWV in our older population. Conclusion: Controlling cardiovascular risk factors, especially high systolic blood pressure, is likely to have the largest beneficial effect on PWV. Improving general physical activity, including walking capacity, may prove beneficial in improving PWV in an older population.

Physical Training vs. Perindopril Treatment on Arterial Stiffening of Spontaneously Hypertensive Rats: A Proteomic Analysis and Possible Mechanisms

(1) Background: Arterial stiffness is an important predictor of cardiovascular events. Perindopril and physical exercise are important in controlling hypertension and arterial stiffness, but the mechanisms are unclear. (2) Methods: Thirty-two spontaneously hypertensive rats (SHR) were evaluated for eight weeks: SHR_C (sedentary); SHR_P (sedentary treated with perindopril-3 mg/kg) and SHR_T (trained). Pulse wave velocity (PWV) analysis was performed, and the aorta was collected for proteomic analysis. (3) Results: Both treatments determined a similar reduction in PWV (-33% for SHR_P and -23% for SHR_T) vs. SHR_C, as well as in BP. Among the altered proteins, the proteomic analysis identified an upregulation of the EH domain-containing 2 (EHD2) protein in the SHR_P group, required for nitric oxide-dependent vessel relaxation. The SHR_T group showed downregulation of collagen-1 (COL1). Accordingly, SHR_P showed an increase (+69%) in the e-NOS protein level and SHR_T showed a lower COL1 protein level (-46%) compared with SHR_C. (4) Conclusions: Both perindopril and aerobic training reduced arterial stiffness in SHR; however, the results suggest that the mechanisms can be distinct. While treatment with perindopril increased EHD2, a protein involved in vessel relaxation, aerobic training decreased COL1 protein level, an important protein of the extracellular matrix (ECM) that normally enhances vessel rigidity.