Clinical and experimental studies have revealed that muscle weakness and wasting are common complications of prednisolone administration.
Many studies have been reported that muscle weakness and atrophy associated with prednisolone treatment developed from alteration of the contractile properties of skeletal muscles with no evidence of peripheral nerve involvement.
The purpose of this work is to study the effect; of prednisolone on the strength (threshold, fatigue and tetanic rise time) of skeletal muscles.
The experimental rats were divided into 5 groups; the control group, rats treated with prednisolone acetate for 5, 10 and 15 days, and rats 30 days after treatment with 15 days by prednisolone. Each experimental groups were injected prednisolone acetate intramuscularly, 8mg/kg daily.
After injection prednisolone into the Quadriceps femoris, the Sciatic nerve were stimulated. The strength of the threshold, fatigue and tetanic rise time developing from the Gastrocnemius were compared with those iii the control group.
The results obtained are as follows,
1. After stimulation of the Sciatic nerve, the average threshold, derived from the Gastrocnemius, in the control group was 235.Omv. The threshold showed a gradual decrease with the increase of duration of prednisolone treatment and down to 123.Omv at 15 days treatment.
2. The average value for fatigue derived 5 seconds after the peak of the tetanic curve was 17.7670 for the control group. As the duration of the prednisolone treatment increased, the fatigue became a gradual decrease and the lowest value, 4.5Io, vas seen with 15 days of prednisolone treatment showing a significant change. For each group, as electrical stimulation was increased to two times four times and ten times of the threshold strength, it showed a significant increase statistically.
3. The average value for the tetanic rise time derived from the curve between the start of the electrical stimulation and the peak of the tetanic curve vas 740.0 msec in the control group. As the duration of the treatment with prednisolone increased, the tetanic rise time was gradually rised and the longest time of 1100.Omsec was observed for the group treated for 15 days showing a significant change. For each group, as electrical stimulation was increased to two times, four times and ten times of the threshold strength, it showed a gradual decrease.
4. In the 30 days after treatment with 15 days by prednisolone, the contractile strength seen from the threshold, fatigue and tetanic rise time were almost recovered back to normal level.
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