Lactate Dehydrogenase in the Rat Mammary Gland

Abstract

Summary

The localization of lactate dehydrogenase activity in the epithelial cells and fat globules of the rat mammary gland is shown. All LD isoenzymes are present in the mammary gland at all stages of development, but their proportions change. As development progresses LD₅ shows the greatest increase in activity, LD₄, LD₃, and LD₂ increase in progressively smaller amounts, while LD₁ changes very little. The use of the relative amounts of type “M” and “H” proteins present is suggested as an index of the degree of differentiation of the mammary gland. The shift in the proportions of the isoenzymes is a further clue to controlling mechanisms of the mammary gland.

The authors are grateful to Dr. R. H. Foote and Dr. J. T. Reid for the loan of equipment and to Dr. M. A. Anderson and Mr. D. M. Lawson for interest and advice.