Postnatal maturation of rabbit renal collecting duct: intercalated cell function

Area of Science:

• Renal Physiology
• Cell Biology
• Acid-Base Balance

Background:

• Intercalated cells are crucial for maintaining the kidney's acid-base balance.
• Understanding the developmental timeline of intercalated cells is key to understanding renal function maturation.

Purpose of the Study:

• To characterize the postnatal maturation of intercalated cells in the rabbit kidney.
• To investigate the developmental changes in pH and function of intercalated cells in different renal regions.

Main Methods:

• Utilized fluorescent dyes (6-carboxyfluorescein diacetate) to identify and quantify intercalated cells in rabbit collecting ducts.
• Employed excitation-ratio fluorometry to measure intracellular pH (pH) of individual intercalated and principal cells.
• Assessed proton pump activity and mitochondrial potential using acridine orange and 3,3'-dipentyloxacarbocyanine.

Main Results:

• The number of intercalated cells in the midcortex doubled during postnatal maturation.
• Cortical intercalated cell pH increased significantly from newborn to adult, while principal cell pH remained constant.
• Immature cortical intercalated cells showed fewer proton pumps and lower mitochondrial potential compared to adult cells.
• Neonatal medullary intercalated cells exhibited mature characteristics, including similar pH, acidic vesicles, and mitochondrial potentials as adult cells.

Conclusions:

• Cortical collecting duct intercalated cells undergo significant postnatal proliferation and maturation.
• Outer medullary collecting duct intercalated cells are largely differentiated by one week of age.
• A centrifugal pattern of postnatal renal maturation is observed, with unknown signaling mechanisms.