Morphologic changes during incubation of renal slices.

Area of Science:

• Cell Biology
• Renal Physiology
• Electron Microscopy

Background:

• Understanding kidney tissue ultrastructure is crucial for renal physiology.
• Incubation conditions can induce cellular changes, impacting experimental results.
• Previous studies have explored renal cortex slice viability but detailed ultrastructural dynamics require further investigation.

Purpose of the Study:

• To investigate the progression of ultrastructural changes in rat and mice renal cortex slices under various incubation conditions.
• To identify specific organelles affected and the timeline of these alterations.
• To evaluate the suitability of the kidney cortex slicing technique for studying luminal membrane absorption.

Main Methods:

• Kidney cortex slices prepared using a Stadie-Riggs microtome.
• Incubation in Tris, Tris-proline, and Hanks media.
• Exposure to different oxygenation (O2-CO2, N2), temperatures (37°C, 23°C), and time intervals (0-120 minutes).
• Ultrastructural analysis using electron microscopy.

Main Results:

• Plasma membranes and mitochondria exhibited the most conspicuous changes.
• Early changes (0-30 min) involved mitochondrial cristae, matrix, and endoplasmic reticulum swelling.
• After 30 min, mitochondria adopted a condensed form, progressing to swollen states with dense material by 75 min.
• Brush border vesiculation and dilation occurred at 30 min, followed by myelinization; antiluminal membrane changes appeared after 75 min.
• Changes were more rapid at 37°C compared to 23°C.
• Cellular uptake of 14C-glycine continued for 2 hours.

Conclusions:

• Kidney cortex slicing may not be ideal for studying luminal membrane absorption.
• Observed ultrastructural changes suggest that commonly accepted organelle appearances may differ from their in vivo functioning state.
• Incubation temperature significantly influences the rate of ultrastructural changes in renal cortex slices.