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Updated: Jul 20, 2026
Measuring Lactase Enzymatic Activity in the Teaching Lab
Published on: August 6, 2018
Susceptibility of lactase to luminal proteases in developing rat intestine
Kamaljit Kaur1, Safrun Mahmood, Akhtar Mahmood
1Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India.
Background:
Postnatal development of rat intestine is associated with a decline in brush-border lactase activity. This phenomenon is similar to the adulthood hypolactasia in humans. However, the mechanism underlying this process is not understood.
Methods:
The effect of luminal proteases from adult rat intestine on the intestinal lactase activity in animals aged 7, 14, 21 and 30 days was studied in in vitro experiments. Lactase levels were estimated using enzyme assays and Western blot analysis.
Results:
Incubation of purified brush borders with increasing concentrations of luminal proteases reduced the lactase activity in intestine of 7-day-old rats, but not in that of adult animals. Western blot analysis revealed low signal of the 220-kDa lactase protein in 7-day-old animals, but not that of older weaned animals.
Conclusions:
Our findings suggest that luminal proteases may be responsible for the maturational decline in intestinal lactase activity.
