VPB 121: Veterinary Physiology - II (2+1)

EFFECT OF HEAT AND COLD - PROCEDURE

• Dissect out a frog and isolate the gastrocnemius muscle and Sciatic nerve complex.
• Fix the muscle-nerve preparation in the frog boar.
• Arrange the apparatus for recording simple muscle curve.
• Record the base line on smoked surface of recording drum.
• Determine the threshold stimu­lus and adjust the height of contraction to approximately three inches above the base line by adjusting the strength of the stimulus.
• Apply normal frog ringer soultion (30° C) to the muscle.
• Set the drum for fast speed and record the muscular contraction.
• Drain off the normal Ringer’s solution from the muscle and replace it with already warmed Ringer’s solution (35° C to 40° C).
• Wait for few minutes to equilibrate the temperature and then record the simple muscle curve on the same base line with same point of stimulus.
• Drain off the warm Ringer’s solution from the muscle and replace it with cold Ringer’s solution (10° C to 20° C).
• Wait for few minutes to allow the muscle-nerve complex to equilibrate in this temperature and record a simple muscle curve on the same base line with same point of stimulus.
• Drain off the cold Ringer’s solution from the muscle and apply very hot Ringer’s solution (>45° C).
• Stimulate the muscle-nerve complex.
• Label the temperatures on corresponding muscle curves.
• Mark the point of stimulus and height for each curve.
• With the help of tuning fork note the time interval (seconds) for latent, contraction and relaxation periods and height of contraction for each curve and tabulate the results.