The effects of high-intensity exercise on skeletal muscle neutrophil myeloperoxidase in untrained and trained rats

Abstract

The primary purpose of this study was to examine the effects of high-intensity acute exercise on neutrophil infiltration in different muscle fiber types of untrained rats and to compare postexercise neutrophil accumulation in muscles of untrained and trained animals. The effect of high-intensity acute exercise on blood neutrophil degranulation reaction in trained animals was also elucidated. Neutrophil enzyme myeloperoxidase (MPO) was determined as a measure of neutrophil migration into muscles and blood neutrophil degranulation. Male albino rats were subjected to acute exercise and 5 weeks of training. The used model of intensive acute exercise consisted of 5, 15, and 25 intermittent swimming bouts with the addition of weight (8% of total body mass) for 1-min each, followed by 1.5-min rest intervals. MPO was analyzed in quadriceps muscle (white and red portion) and in soleus muscle 24 h after acute exercise. MPO content in resting blood plasma and neutrophils was determined 48-h following the completion of a training process. In addition, MPO content in the trained rats was measured immediately (in blood plasma and neutrophils) after and 24 h (in muscles) following a single-bout of exercise to exhaustion. The remaining two-third of the trained animals were exposed to a single-bout of nonstop swimming with the addition of 6% body mass until exhaustion. These animals were sacrificed immediately and 24 h after loaded swimming to analyze leukocyte count, MPO content in blood plasma and neutrophils and in muscles, respectively. About 24 h after exercise MPO concentrations in the red portion of quadriceps muscle and in soleus muscle were 4-7-fold higher as compared to the white portion of m. quadriceps. There was an association between the quantity of repetitive bouts of swimming and MPO content in the muscles. The duration of swimming to exhaustion of trained rats was 3.8-fold longer than untrained sedentary control. At rest, plasma MPO concentration was found to be 40% higher in trained rats compared to untrained controls (P < 0.05). Postexercise plasma MPO concentrations were significantly higher both in untrained (+137%; P < 0.05) and trained (+81%; P < 0.05) rats compared to resting values. At rest neutrophil MPO concentration was found to be 33% lower in trained rats compared to untrained controls (P < 0.05). There were no significant differences in muscle MPO concentrations between untrained and trained rats at rest. A single-bout of exercise to exhaustion produced a greater increase in MPO content in untrained compared to trained rats. The data suggest that postexercise neutrophil infiltration is more intensive in red fibers types compared to white fiber types. A smaller neutrophil infiltration in muscles of trained animals after exhaustive exercise suggests a protective effect of previous training to muscle injury.

Efeito do exercício no sistema imune: resposta, adaptação e sinalização celular

“…Significant differences have not been observed in the concentration of protein markers for neutrophil activity (MPO) between rats trained, untrained or at rest. However, a single session of exhaustive exercise produced significant MPO increases in untrained animals compared to the trained group suggesting a possible protective effect from training in the muscle tissue 44 .…”

Effects of zinc supplementation on hematological parameters of high performance athletes

“…There is a report on the effect of high intensity acute exercise on neutrophil infiltration and accumulation in muscle tissues of trained and untrained rats (Morozov et al, 2006).…”

The Role of the Innate and Adaptive Immunity in Exercise Induced Muscle Damage and Repair

“…In addition, cfDNA and HMGB-1 levels display similar kinetics to other established muscle damage markers such as lactate and myoglobin [35,65]. Interestingly, across murine and human models, sedentary subjects have a greater inflammatory response to cfDNA when compared to trained counterpart [67,68]. which corresponds to low impact exercise activity, induces little or no infiltration of leukocytes into the damaged muscle [5,69].…”