Perinatal development of tubular function in the pig

Area of Science:

• Nephrology
• Comparative Physiology
• Developmental Biology

Background:

• Renal tubular function is critical for maintaining homeostasis.
• Understanding developmental changes in kidney function is essential for perinatal physiology.

Purpose of the Study:

• To investigate changes in renal tubular function from fetal to newborn pigs.
• To characterize the transport mechanisms of glucose and fructose in developing porcine kidneys.

Main Methods:

• Experiments conducted on anesthetized fetal and newborn pigs.
• Urine collection via ureteral catheterization.
• Measurement of glomerular filtration rate and plasma/urinary concentrations of various solutes (electrolytes, urea, glucose, fructose, creatinine, etc.).
• Assessment of water reabsorption in relation to vasopressin levels.
• Fructose and glucose loading tests to determine maximal tubular transport rates.

Main Results:

• Significant functional changes in the renal tubule system occur around birth.
• Increased reabsorption of sodium and water is a key adaptation to extra-uterine life.
• Apparent increased tubular impermeability to creatinine post-birth.
• Fructose transport shifts from reabsorption in fetuses to net secretion in neonates.
• Distinct transport mechanisms exist for glucose and fructose, with at least two identified for fructose (reabsorption and secretion).

Conclusions:

• The transition from fetal to neonatal life involves critical adaptations in renal tubular function, particularly in sodium and water handling.
• Fructose transport exhibits developmental plasticity, with distinct reabsorptive and secretory pathways.
• Further research is needed to elucidate the regulatory factors influencing fructose transport mechanisms in newborn pigs.