Enzyme activities of energy metabolism in skeletal muscle, and in the uterus, during late pregnancy in the mouse.

Abstract

Three hindleg muscles (white and red quadriceps, soleus), and uterine tissue, from late pregnant NMRI mice were analyzed for selected enzyme activities of energy metabolism. In addition, skeletal muscle fibre type distribution and fibre diameters were estimated in some animals. No differences between pregnant and non-pregnant animals were found for any enzyme in any of the tissues. Neither were there any differences in muscle morphology. It was concluded, that the increased work load, and altered plasma substrate profile, during late pregnancy do not induce metabolic or morphological adaptations in skeletal muscle. Furthermore, the smooth muscle of the murine myometrium does not increase its metabolic capacity in preparation for parturition, suggesting that the base-line metabolic capacity is sufficient for the work involved. The morphological and metabolic characteristics of the three skeletal muscles were similar to those in the rat. Compared with these muscles, the uterus had a low metabolic capacity, and appeared to rely predominantly on fatty acid oxidation.