Uridine phosphorylase activity during postnatal development of the rat heart

Area of Science:

• Biochemistry
• Developmental Biology
• Cardiovascular Physiology

Background:

• Uridine phosphorylase (UP) is an enzyme involved in nucleotide metabolism.
• Heart development involves complex cellular processes including hyperplasia and hypertrophy.
• The specific role of UP during early cardiac development is not well understood.

Purpose of the Study:

• To investigate the activity profile of uridine phosphorylase in rat hearts during postnatal development.
• To correlate changes in UP activity with the developmental shift from cellular hyperplasia to hypertrophy.

Main Methods:

• Assay of uridine phosphorylase activity in heart extracts from rats at various postnatal ages.
• Determination of the protein/DNA ratio to identify the transition from hyperplasia to hypertrophy.

Main Results:

• Uridine phosphorylase activity was low at birth, increased significantly to a peak between 8-14 days post-birth, and then declined to adult levels.
• The shift from cellular hyperplasia to hypertrophy, indicated by the protein/DNA ratio, occurred around day 18 of development.
• The peak of uridine phosphorylase activity preceded the transition to hypertrophy.

Conclusions:

• The temporal pattern of uridine phosphorylase activity suggests a significant role during early rat heart development.
• The activation of uridine phosphorylase during early postnatal life may be a critical factor initiating cardiac hypertrophy.