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

DETERMINATION OF THE PTYALIN ACTIVITY

• Take 5 ml of the soluble starch in a test tube.
• Add 2 ml of a buffer solution of pH 6.7 and 2 ml of 0.5% NaCl solution. Keep the tube in a water bath at 37°C.
• Arrange serially numbered test tubes each containing 3 ml of distilled water and two drops of dilute iodine solution.
• Add 2 ml of saliva to the warmed buffed starch solution, mix well and note the time.
• Transfer a drop or two of the mixture to a tube containing dilute iodine at 15 seconds interval and shake well.
• The time at which additions of the solution fails to produce any colour indicates the complete conversion of last trace of erythrodextrin into achrodextrin and maltose which is known as the “Achromic point”.
• The time taken to reach this point (chromic period) is the measure of ptyalin activity.