Abstract

Aerobic exercise promotes short-term physiological changes in the intestinal smooth muscle associated to the ischemia-reperfusion process; however, few studies have demonstrated its effect on the intestinal contractile function. Thus, this work describes our observations regarding the influence of acute aerobic swimming exercise in the contractile reactivity, oxidative stress, and morphology of rat ileum. Wistar rats were divided into sedentary (SED) and acutely exercised (EX-AC) groups. Animals were acclimated by 10, 10, and 30 min of swimming exercise in intercalated days 1 week before exercise. Then they were submitted to forced swimming for 1 h with a metal of 3% of their body weight attached to their body. Animals were euthanized immediately after the exercise section and the ileum was suspended in organ baths for monitoring isotonic contractions. The analysis of lipid peroxidation was performed in order to determinate the malondialdehyde (MDA) levels as a marker of oxidative stress, and intestinal smooth muscle morphology by histological staining. Cumulative concentration-response curves to KCl were altered in the EX-AC with an increase in both its efficacy and potency (Emax = 153.2 ± 2.8%, EC50 = 1.3 ± 0.1 × 10−2 M) compared to the SED group (Emax = 100%, EC50 = 1.8 ± 0.1 × 10−2 M). Interestingly, carbachol had its efficacy and potency reduced in the EX-AC (Emax = 67.1 ± 1.4%, EC50 = 9.8 ± 1.4 × 10−7 M) compared to the SED group (Emax = 100%, EC50 = 2.0 ± 0.2 × 10−7 M). The exercise did not alter the MDA levels in the ileum (5.4 ± 0.6 μ mol/mL) in the EX-AC compared to the SED group (8.4 ± 1.7 μ mol/mL). Moreover, neither the circular nor the longitudinal smooth muscle layers thickness were modified by the exercise (66.2 ± 6.0 and 40.2 ± 2.6 μm, respectively), compared to the SED group (61.6 ± 6.4 and 34.8 ± 3.7 μm, respectively). Therefore, the ileum sensitivity to contractile agents is differentially altered by the acute aerobic swimming exercise, without affecting the oxidative stress and the morphology of ileum smooth muscle.

Highlights

  • In recent decades, human behavioral changes has promoted the development of inappropriate habits such as sedentary lifestyle, which increasingly affects the quality of life

  • Cumulative concentration-response curve to KCl (10−3–10−1 M) was leftward shifted in the EX-AC group compared with the control (Figure 1A), with Emax increase and EC50 reduction (Table 1)

  • We investigated the influence of acute aerobic swimming exercise on the contractile reactivity, oxidative stress, and morphology of rat ileum, and we showed that this modality of exercise produces different changes in the rat ileum reactivity to electro- and pharmacomechanical couplings without altering lipid peroxidation and organ morphology

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Summary

Introduction

Human behavioral changes has promoted the development of inappropriate habits such as sedentary lifestyle, which increasingly affects the quality of life. Continuous aerobic exercise stimulates adaptations in the cardiovascular, respiratory, and muscular systems in order to maintain the tissue oxygen demand, related to structural and functional changes, categorizing as chronic exercise (Hermansen and Wachtlova, 1971; Brodal et al, 1977; Howley, 2001). The aerobic exercise can subject several organs to a process of ischemia-reperfusion due to the diversion of blood flow to the skin and the active skeletal muscle. The intestinal smooth muscle is not directly involved in physical exercises, it is submitted to this physiological stress related to the process of ischemia-reperfusion (Otte et al, 2001). It is described that the exercise can promote ischemia and motor abnormalities in both gut and intestinal mucosa (Ballabeni et al, 2002)

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