Efeitos do treinamento físico sobre a síntese/armazenamento de noradrenalina em arteríolas musculares esqueléticas e renais de ratos hipertensos espontâneos

Abstract

We showed recently that pressure fall in trained spontaneously hypertensive rats (SHR) is correlated with decreased vascular resistance and skeletal muscle wall/lumen ratio normalization without changes in renal arterioles (J. Hypertens. 18: 1563(J. Hypertens. 18: , 2000 Hypertension 42 [part 2]: 851, 2003). In the present study, we investigated the effects of physical training on sympathetic vascular innervation to different tissues and adrenal catecholamines (hormoral response).Male SHR (~2 months) were submitted to treadmill physical training (50-60% of maximal exercise capacity, 1 h/day, 5 d/weeks, 3 months) or kept sedentary (S), and then instrumented for pressure (AP) and heart rate (HR) recordings at rest. Rats were deeply anesthetized and tissues (soleus, gastrocnemius red, gracilis = locomotor; temporalis = non-locomotor muscle; kidney and adrenals) were collected for immunohistochemistry (PBS + PFA 4%, half of the rats in each group) and expression (Western Blot analysis) of tyrosine hydroxylase (TH).Physical training improved treadmill performance (+0.60±0.13 km/h), and reduced AP and HR at rest (177±3 mmHg and 319±7 b/mim, corresponding 6% and 10% fall vs S group, p<0.05). After physical training, TH immunoreactivity was increased in locomotor muscles (+57% on average, p<0.05) with smaller changes in the temporalis (+24%, p>0.05), without any change in kidney arterioles. Traininginduced TH imunorreactivity increase within the locomotor muscles was accompanied by significant reduction of arterioles wall/lumen ratio. There was no change on TH expression in the adrenals.