Trypsin activity in the small intestine of rats after application of copper and zinc.

In vivo experiments with Sprague-Dawley rats were conducted in order to explore the influence of Cu(2+), Zn(2+) as well as of the combinations of both on the activity of trypsin. The solutions of the trace elements were given per os, the animals were killed 30 min after the applications, and the activity of trypsin was determined in the juice of the small intestine by usingN (α)-benzoyl-L-arginine-p-nitroanilide (L-BAPA) as the substrate. The activity of trypsin depends on the concentration of the trace elements. When Cu(2+) ions are applied, there is a minimum activity at 10(-5) mol Cu(2+)/L and a maximum at 10(-4) mol Cu(2+)/L. When giving Zn(2+) ions, a minimum of trypsin activity is found at 10(-5) mol Zn(2+)/L and a maximum at 5×10(-6) mol Zn(2+)/L. On the whole, the trypsin activity is lower when the Cu(2+)/Zn(2+) combinations are applied compared to the addition of the single trace elements. On principle, a good conformity of the in vivo results was found with in vitro results.