Effect of temperature on the maximum rate of rise of tension in denervated rat diaphragm muscle

Effects of chronic denervation and temperature were studied on the maximum rate of rise of tension in isometric twitch and tetanus of rat diaphragm muscles. The muscles were denervated for 15-20 days and the maximum rate of rise of tension was measured according to Hill (1951). The results showed that the maximum rate of rise of tension in twitch and tetanus was temperature dependent, exponentially increasing with increasing temperatures in both the normal and denervated muscles. A further observation was that the maximum rate of rise of tension in denervated muscle was always smaller than normal controls. It is suggested that probable changes in the series elasticity and duration of active state in the denervated muscle are responsible for the observed changes.

Effect of hypothermia on the twitch and tetanic contractions of denervated rat diaphragm muscle under isotonic conditions

Effect of hypothermia was studied on the twitch and tetanic contractions of the chronically denervated rat diaphragm muscles under isotonic conditions. The muscles were denervated for 15-20 days and the temperature was lowered from 35 degrees C to 15 degrees C. The results showed that hypothermia and chronic denervation had very little effect on the isotonic contraction parameters since these were found to be unaltered at all temperatures except at 15 degrees C. It is suggested that denervation has no significant effect on the contractile component of our experimental muscles.