The present study was performed to observe the effect of ammonia, which was in-creased during exercise, on the muscular fatigue in rat gastroctiemius-soleus muscle.
In experimental group ll with applying ammonia (1800 ㎍/㎏) intravenously, contractile tension of gastrocnemius-soleus muscle evoked by electrical stimulation was recorded to observe the complete tetanic response and single twitch response. Electrical stimulation was done in sciatic nerve supramaximally. Results of experimental group ll were compared with results of experimental group I with applying lactate (50 ㎍/㎏) intravenously, with results of control group I without anything in first experiment.
In second experiment, experimental group1V was exercised in swimming bath to exhausted state with applying ammonia intravenously, control group ll was exercised with-out anything and experimental group)ll with applying lactate. After that, the complete tetanic response and single twitch response were obtained and compared through the same method. The results are summarized as follows.
1. The increased ammonia resulted in increase of threshold for rat muscle contraction.
2. During complete tetanic response, the increased ammonia resulted in decrease of ratio between the time to be a peak tetanic tension and amplitude of peak tetanic tension.
3. During complete tetanic response, rat muscle gradually reduces its tension output, which were interpreted as a sign of muscular fatigue. The increased ammonia was tend to decrease in ratio between the time and the amplitude of reduced tension output, but this decrease have no significant meaning statistically.
4. Under the continuous electrical stimulation (2 Hz), the maximal twitch response and complete tetanic response were recorded at every thirty-seconds. Decreasing rate of maximal twitch tension and peak tetanic tension were increased in hyperammonized rat.
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