AJP - Heart and Circulatory Physiology, Vol 243, Issue 1 87-H93, Copyright © 1982 by American Physiological Society
Ultrastructural and enzymatic development of fetal guinea pig heart
T. P. Rolph, C. T. Jones and D. Parry
The activities of some enzymes of glycolysis, the citric acid cycle, and
amino acid metabolism have been measured in the fetal guinea pig heart over
the last third of gestation and correlated with heart ultrastructural
development. There is little change in glycolytic enzyme activity except
for a two- to threefold increase in phosphofructokinase activity.
Mitochondrial content and enzyme activities are low in the early fetal
heart, and, although content is similar in the late fetus and adult, enzyme
activities increase twofold postnatally, indicating fetal heart
mitochondria are incompletely developed. The activities of aspartate and
particularly alanine aminotransferase are low in the fetal heart. Over the
last third of gestation the myofibrillar content of the fetal myocyte
increases twofold to the adult value by term. Associated with this is a
fourfold rise in myofibrillar and sarcoplasmic reticulum Ca2+-ATPase
activity. Na+-K+-ATPase activity is similar in the late fetal and adult
heart but one-third lower in the early fetal heart.
