Background: Baroreceptors act as regulators of blood pressure (BP), however, its sensitivity is impaired in hypertensive patients. Among the recommendations for BP reduction, exercise
training has become an important adjunct therapy in thesepopulation. Therefore, the aim of this study was to evaluate the effect of resistance exercise training in spontaneously hypertensive rats
Methods:SHR and Wistar rats 8 weeks old at the beginning of the experiment were randomly divided into 4 groups: sedentary control (SC, n=8); trained control (TC, n=8); SHR sedentary
(SHRS, n=8) and SHR trained (SHRT, n=8). Resistance exercise training was performed in climb a vertical ladder (1.1×0.18 m, 2-cm grid, 80° incline) with weights attached to their tails, 5 times per
week, during 8 weeks. Body mass and BP were measured weekly by semi-analytical scale and tail plethysmography system, respectively. After resistance exercise training period, the animals underwent
arteriovenous implanted catheters for direct registration of pulsatile arterial pressure. Baroreceptor reflex control of heart rate (HR) was tested by loading/unloading of baroreceptors with
phenylephrine (3, 5 and 10 µg - iv) and sodium nitroprusside (5, 15 and 20 µg - iv). Phenylephrine and nitroprusside injections (0.1 ml, bolus injection) were given in a random order, and subsequent
injections were not made until the recorded parameters had returned to pre-injection levels.
Two-way ANOVA was used to determine the differences among the groups followed by Student D’Agostino and Pearson post hoc testand was adopted p <0.05 as significant result.
Results:After the resistance exercise training period SHR had lower body mass (SHRS 256.3±8.37 g and SHRT 246.9±7.75 g) compared to control groups (SC 310.7± 11.44 g and TC 295.3 ±
11.20 g). Resistance exercise training was able to increase the soleus muscle mass in SHR (SC 0.046±0.005 g/mm, TC 0,063±0,006 g/mm, SHRC 0.027±0.002 g/mm and SHRT 0.056±0.003 g/mm). BP was not
altered by resistance exercise training. On the other hand, in relation to baroreflex sensitivity, bradycardic response was improvement in the SHRT group (SC -2.67±0.06 bat/mmHg, TC -3.2±0.16
bat/mmHg, SHRS -1.3±0.1 bat/mmHg and SHRT -2.6±0.2 bat/mmHg) although tachycardia response was not altered by resistance exercise training ( SC -3,3±0,2 bat/mmHg, TC -3,3±0,1 bat/mmHg, SHRS
-1,47±0,06 and SHRT -1,6±0,1 ).
Conclusions:Conclusion: Resistance exercise training was able to promote improvement on baroreflex sensitivity of SHR since promoted improvement in bradycardic
response despite not having reduced BP