Training in swimming reduces blood pressure and increases muscle glucose transport activity as well as GLUT4 contents in stroke-prone spontaneously hypertensive rats

Is 3 Weeks of Exercise Enough to Change Blood Pressure and Cardiac Redox State in Hypertensive Rats?

The investigation was aimed to evaluate the effects of 3-weeks swimming exercise on blood pressure and redox status in high-salt-induced hypertensive rats. Male Wistar albino rats (n=40, 6 weeks old) were divided into 4 groups: 1. hypertensive rats that swam for 3 weeks; 2. sedentary hypertensive control rats; 3. normotensive rats that swam for 3 weeks; 4. sedentary normotensive control rats. Hypertensive animals were on high concentrated sodium (8% NaCl) solution for 4 weeks (period of induction of hypertension). After sacrificing, hearts were isolated and perfused according to Langendorff technique at gradually increased coronary per-fusion pressure from 40–120 cmH2O. The oxidative stress markers were determined in coronary venous effluent: the index of lipid peroxidation (measured as TBARS), nitrites (NO2 −), superoxide anion radical (O2 −) and hydrogen peroxide (H2O2). Swimming did not lead to significant changes in levels of TBARS, NO2 −, O2 − in any of compared groups while levels of H2O2 were significantly higher in swimming hyper-tensive group comparing to swimming normotensive group at coronary perfusion pressure of 80–120 cmH2O. Our results indicate that the short-term swimming start to reduce blood pressure. In addition it seems that this type of swimming duration does not promote cardiac oxidative stress damages.

Aortic wall proteomic analysis in spontaneously hypertensive rats with a blood pressure decrease induced by 6-week load-free swimming

Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall in hypertension. The proteomic approach is a powerful technique to analyze a complex mixture of proteins in various settings. Physical activity level was negatively associated with blood pressure. Sixteen 4-week-old male spontaneously hypertensive rats (SHR) and 16 Wistar-Kyoto (WKY) rats were randomly divided into four groups: i) SHR exercise group, ii) SHR rest group, iii) WKY exercise group and iv) WKY rest group. In the SHR and WKY exercise groups, rats were treated with a 6-week load-free swimming protocol (1 h/day, 5 days/week). The blood pressure of the rats was tested by the CODA^TM2 single non-invasive blood pressure measurement appliance. After the 6-week swimming protocol, the total aorta excluding abdominal aorta was extracted. The proteins were separated by two-dimensional gel electrophoresis and identified via LC-mass spectrometry (MS)/MS. After 6-week load-free swimming, blood pressure decreased in the SHRs. Compared with sedentary SHRs, 11 spots on the 2D-gel showed a significant difference in exercised SHRs. Nine of these were chosen for further identification. There were 5 upregulated proteins (long-chain specific acyl-CoA dehydrogenase, heat shock protein β-1, isocitrate dehydrogenase subunit α, actin, α cardiac muscle 1 preprotein and calmodulin isoform 2) and 4 downregulated proteins (adipocyte-type fatty acid-binding protein, tubulin β-2C chain, 78 kDa glucose-regulated protein precursor and mimecan). Proteomics is an effective method to identify the target proteins of exercise intervention for hypertension.

Caffeine supplementation modulates oxidative stress markers in the liver of trained rats

AIMS

Caffeine has been widely used in sports competitions due to its ergogenic effects. Most of the studies regarding caffeine and exercise have focused on muscle and plasma adaptations, while the impact on the liver is scarcely described. The aim is to analyze the effects of caffeine and exercise training on oxidative stress markers and injury-related parameters in the liver.

MAIN METHODS

Rats were divided into sedentary/saline, sedentary/caffeine, exercise/saline, and exercise/caffeine groups. Exercise groups underwent 4 weeks of swimming training, and caffeine (6 mg/kg, p.o.) was supplemented throughout the training protocol. Injury-related liver parameters were assessed in plasma, while redox status and oxidative stress markers were measured on liver homogenates.

KEY FINDINGS

Exercise training increased muscle citrate synthase activity in the muscle, while in caffeine decreased its activity in both sedentary and trained rats. Aspartate transaminase levels were increased after training, and caffeine intake suppressed this elevation (p<0.05). Caffeine also diminished alanine transaminase levels in both sedentary and exercised rats (p<0.05). Exercise training induced a significant increase on the activity of the enzymes superoxide dismutase and glutathione peroxidase, as an increase on thiobarbituric acid-reactive substances levels was also reached (p<0.05); caffeine intake blunted these alterations. Caffeine intake also suppressed liver catalase activity in both sedentary and exercise groups (p<0.05).

SIGNIFICANCE

Our data suggest that caffeine modified the hepatic responses associated to exercise-induced oxidative stress without affecting the performance, exerting different actions according to the tissue. However, further studies are needed to better understand caffeine's role on liver under exercise training.

The effects of a 10-week water aerobic exercise on the resting blood pressure in patients with essential hypertension

PURPOSE

To investigate the effects of a 10-week water aerobic exercise on the resting blood pressure in patients with stage 1 or 2 hypertension referring to Tehran University Clinics.

METHODS

Forty men with stage 1 or 2 essential hypertension were assigned to two groups of intervention [n = 12; aged 48.33±10.74 years (mean±SD)] and control [n = 28; aged 46.96±11.58 years (mean±SD)]. Subjects in the intervention group participated in a supervised 10-week water aerobic training program of 55 min sessions, 3 days per week on alternate days, while those in the control group were not involved in any regular training program during this period. Blood pressure of the participants was recorded and compared at the beginning and at the end of the study (48 hours after the last training session).

RESULTS

Exercise lowered systolic blood pressure and mean arterial pressure by 11.71 (95% confidence interval: 5.07 to 18.35) and 5.90 (95% confidence interval: 1.17 to 10.63) mm Hg respectively. The lowering effect of exercise on diastolic blood pressure was neither statistically significant nor clinically important (0.55 mm Hg; P. value = 0.8). There was no significant effect of age, baseline body mass index and stage of hypertension on the exercise-induced changes in blood pressure.

CONCLUSION

A 10-week course of water aerobic exercise markedly reduced the systolic and mean arterial blood pressure of patients with essential hypertension and is especially recommended for the obese and the elderly who have orthopedic problems or bronchospasm.

Involvement of the atrial natriuretic peptide in the reduction of arterial pressure induced by swimming but not by running training in hypertensive rats

The aim of this study was to compare, under resting conditions, the influence of chronic training in swimming or running on mean arterial pressure (MAP) and the involvement of the natriuretic peptide system in this response. Two-month-old male spontaneously hypertensive rats (SHR) were divided into three groups-sedentary (SD), swimming (SW) and running (RN)-and were trained for eight weeks under regimens of similar intensities. Atria tissue and plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay. ANP mRNA levels in the right and left atria as well as the natriuretic peptide receptors (NPR), NPR-A and NPR-C, mRNA levels in the kidney were determined by real-time PCR. Autoradiography was used to quantify NPR-A and NPR-C in mesenteric adipose tissue. Both training modalities, swimming and running, reduced the mean arterial pressure (MAP) of SHR. Swimming, but not running, training increased plasma levels of ANP compared to the sedentary group (P<0.05). Expression of ANP mRNA in the left atrium was reduced in the RN compared to the SD group (P<0.05). Expression of NPR-A and NPR-C in the kidneys of the SW group decreased significantly (P<0.05) compared to the SD group. Although swimming increased (125)I-ANP binding to mesenteric adipose tissue, displacement by c-ANF was reduced, indicating a reduction of NPR-C. These results suggest that the MAP reduction induced by exercise in SHR differs in its mechanisms between the training modalities, as evidenced by the finding that increased levels of ANP were only observed after the swimming regimen.

Low-intensity voluntary running lowers blood pressure with simultaneous improvement in endothelium-dependent vasodilatation and insulin sensitivity in aged spontaneously hypertensive rats

Our objective is to examine the effects of voluntary running at different intensity levels on blood pressure, endothelium-dependent vessel dysfunction and insulin resistance in aged spontaneously hypertensive rats (SHR) with severe hypertension. Ten-month-old male and female SHR with severe hypertension were assigned to voluntary running at either low intensity (30% of maximal aerobic velocity) or moderate intensity (60% of maximal aerobic velocity) on a motor-driven treadmill for 6 weeks, 20 min per day and 7 days per week. Age-matched Wistar-Kyoto rats and SHR were kept under sedentary conditions as controls. Blood pressure and heart rate were measured by the tail-cuff method. At the end of the exercise training, blood samples were collected for glucose, insulin and lipids assay, and aortae were isolated to examine their function in vitro. Low-intensity but not moderate-intensity running significantly lowered blood pressure in both male and female SHR (p<0.01). There was significant impairment in acetylcholine-induced vasorelaxation in SHR (p<0.01), which was improved by low-intensity training (p<0.05). Nitric oxide synthase blockade abrogated the improvement in endothelium-dependent relaxation. Hypertensive rats had elevated blood glucose and insulin levels with lowered insulin sensitivity that was ameliorated by low-intensity running. A significant increase in blood high-density lipoprotein (HDL)-cholesterol and a significant decrease in triglycerides were found in exercised SHR. In conclusion, low-intensity voluntary exercise lowers hypertension in aged SHR with severe hypertension. Exercise-induced simultaneous improvement in endothelium-dependent vessel relaxation and insulin sensitivity may act concomitantly in attenuating cardiovascular risk factors in aged hypertensive rats with significantly high blood pressure.

The effect of repeated episodes of dietary restriction and refeeding on systolic blood pressure and food intake in exercise-trained normotensive rats

OBJECTIVE

To explore the effects of weight cycling and exercise on blood pressure and macronutrient intake in Sprague-Dawley rats.

RESEARCH METHODS AND PROCEDURES

Female Sprague-Dawley rats (n = 62; 5 months old) were assigned to an ad libitum (Con) or weight-cycled (Cyc) group. They were either sedentary (Con-Sed and Cyc-Sed) or exercise-trained (Con-Ex and Cyc-Ex) on a motorized treadmill (20 m/minute; 60 minutes/day; 6 days/week). The Cyc groups underwent 2 cycles of 3 weeks of 60% food restriction followed by 5 weeks of ad libitum refeeding using a macronutrient self-selection diet. Body mass and food intake were analyzed weekly. Systolic blood pressure (SBP) was measured at baseline and during the first and fifth weeks of each refeeding.

RESULTS

For both cycling periods, SBP was elevated in Cyc vs. Con groups at Week 1 of refeeding, but was similar among groups by Week 5 of refeeding. Both Con groups had greater total energy intake than the Cyc groups for both cycling periods (Cycle 1: 2882.2 +/- 75.1, Con-Sed; 2916.1 +/- 67.1, Con-Ex; 2692.2 +/- 58.7, Cyc-Sed; and 2780.5 +/- 52.4 kcal, Cyc-Ex) (Cycle 2: 2815.8 +/- 75.1, Con-Sed; 2938.8 +/- 49.4, Con-Ex; 2577.1 +/- 60.5, Cyc-Sed; and 2643.5 +/- 65.9 kcal, Cyc-Ex). Relative fat intake (percentage of total kcal/week) was significantly less for Con-Ex and Cyc-Ex than Con-Sed and Cyc-Sed throughout both refeeding periods.

DISCUSSION

Weight cycling failed to produce significant sustained effects on SBP, body mass, or food intake. Exercise training, irrespective of diet, lowered dietary fat intake.