ABSTRACT
This study reviewed the influence of hypoxic training on hypoxic pulmonary vasoconstriction (HPV) sensitivity in the isolated perfused lungs preparation of rats. In addition, the study examined the kind of mechanism involved. Therefore, we inhibited nitric oxide (NO) release of endothelial cells, using on NO synthase inhibitor, and reviewed the impact on HPV.As a result, the following became clear. 1)Hypoxic training inhibited HPV. 2) HPV was increased by the administration of NO synthase inhibitor L-NMMA, in particular, conspicuously inhibited HPV in the hypoxic training group was increased. 3) The negative correlation between the onset of blood lactate accumulation and HPV was significant.From the above, it can be concluded that hypoxic training inhibited HPV and NO release for a pulmonary vascular endothelial cell. In addition, we understood that HPV was decreased by hypoxic training as the ability for endurance exercise was increased.
ABSTRACT
Previously, we observed that hypoxic pulmonary vasoconstriction (HPV) can be reduced by endurance exercise training. This study determined whether nitric oxide (NO) plays a role in inhibition of the HPV after endurance exercise training in isolated rat lung perfused with physiological saline solution containing meclofenamate. Sprague-Dawley rats were used, and were divided into two groups: a control (Cont) group and an endurance exercise-trained (ET) group. Endurance exercise training was carried every day on a small-animal motorized treadmill. The training protocol was 30 to 40 min/day and the rats ran at a speed of 15 to 30 m/min for 2 weeks. It appeared that HPV could be reduced by short-term endurance exercise training. The NO-forming enzyme inhibitor, N<SUP>G</SUP>-nitro-L-arginine methyl ester (1.5×10<SUP>-8</SUP>M, L-NAME), administered to the ET group increased the HPV compared in that of the Cont group. These findings indicate that endothelial NO synthesis may contribute to the inhibition of HPV in ET rats. Our data suggest that endurance exercise training promotes endothelium dependent-pulmonary vasodilation through the stimulation of NO released during HPV.
ABSTRACT
A study was conducted to investigate muscle fatigue during isometric contraction of the indicis proprius using EMG analysis (BIMUTAS Ver. 2. 1) .<BR>The subjects were 8 healthy men (ranging in age from 19 to 42 years) .<BR>Plummets (ranging from 300g to 600g) were placed on the distal knuckle of the index finger to create loads on the indicis proprius muscle. EMG was recorded until the plummet dropped, and the total time required was divided into 10 equal parts. In each part, the EMG record for the first 1000 ms was picked out. Then the mean power frequency (MePF) and median power frequency (MdPF) of the power spectrum were calculated.<BR>The results were as follows:<BR>1) Both MePF and MdPF showed shits to lower frequency bands.<BR>2) Integrated values of the EMG power spectrum increased with time.<BR>3) The time courses of the MePF and MdPF in each EMG sample for the 8 subjects were determined by the 3-point moving average method.<BR>A break-point was observed in each MePF and MdPF diagram.<BR>It was considered that two-break points observed in the time courses of the EMG record were valid as an objective index of local muscle fatigue.