The effect of diazepan and exercise training on selected biochemical and histochemical properties of rat skeletal muscle.

The effects of chronic diazepam (D) treatment and exercise training on total body mass (TBM), microsomal protein yield (MPY), calcium uptake by fragmented sarcoplasmic reticulum (SR), muscle fibre cross-sectional area, and both PFK and SDH activities were investigated in the tibialis anterior (TA), soleus (Sol), and plantaris (Plt) muscles of 50 male albino Sprague-Dawley rats. Rats were assigned randomly to control (C), sprint-trained (S), or endurance-trained (E) groups. Training was of 12 weeks duration. One-half of each group received daily intraperitoneally D doses of 5 mg kg-1 of TBM. Exercise reduced TBM (p < 0.05); increased the relative BM of the TA (E = 2.02 +/- 0.02, p < 0.01) and Plt (E = 1.15 +/- 0.02, p < 0.01; S = 1.13 +/- 0.03, p < 0.01), as well as the Ca++ uptake of the Sol SR (C = 0.08 +/- 0.02, E = 0.16 +/- 01, p < 0.05). MPY was elevated in S-Sol (C = 1.12 +/- 0.6, S = 1.52 +/- 0.1, p < 0.01). D elevated Sol MPY as well as TA PFK. S-trained animals had lower mean fibre areas than the E-trained (D-treated and untreated) animals. The elevated relative masses of TA and Plt are explained by a decreased TBM with exercise. The increased Ca++ uptake of the Sol indicates that E enhances this function, and the increased MPY probably implies an increased SR. The D could be responsible for the D-elevated Sol MPY as well as the TA PFK. El D did not reduce neuromuscular activity to a level adversely affecting oxidative enzyme activity, but in the case of PFK activity in the TA muscle, such a reduction was evident.