Developmental decrease in rat small intestinal creatine uptake

Area of Science:

• Physiology
• Biochemistry
• Molecular Biology

Background:

• Phosphocreatine serves as a vital energy buffer and transducer in key tissues like the heart, brain, and skeletal muscle.
• The Na+/Cl-/creatine transporter has been identified at the apical membrane of the small intestinal epithelium, suggesting a role in creatine uptake.

Purpose of the Study:

• To investigate the developmental changes (ontogeny) and regional differences (segmental distribution) of creatine transport activity in the rat small intestine.
• To elucidate the characteristics of the creatine transport system in different segments of the rat intestine across various life stages.

Main Methods:

• Quantification of [14C]-creatine uptake in the jejunum and ileum of rats at multiple developmental stages, from fetal to adult.
• Measurement of creatine content in maternal and infant diets (amniotic fluid, milk, rat chow) using High-Performance Liquid Chromatography (HPLC).

Main Results:

• NaCl-dependent creatine uptake was highest in newborn rats and consistently higher in the ileum than the jejunum across all ages studied.
• Creatine uptake in the jejunum became undetectable after weaning, while ileal uptake showed a periweaning decline that could be partially mitigated by creatine supplementation.
• Kinetic analysis indicated that both jejunum and ileum utilize the same creatine transport system, with maturation primarily affecting Vmax rather than apparent Km.

Conclusions:

• The rat small intestine employs a single transport system for creatine uptake along its length.
• Creatine transport activity undergoes significant, maturation-dependent changes, appearing genetically programmed and regulated by intestinal creatine levels.
• Dietary creatine supplementation can influence intestinal creatine uptake, particularly in the ileum, highlighting the interplay between diet and intestinal physiology.