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Morphologic changes during incubation of renal slices
Abstract:
The progression of ultrastructural changes was studied during various conditions of incubation of rat and mice renal cortex slices. The kidneys were sliced with a Stadie-Riggs microtome and incubated in various media (tris(hydroxymethyl) aminomethane (Tris), Tris-proline, and Hanks), in different oxygenation conditions (O2-CO2, 6 liters per minute; N2, 0.5 liter per minute), at different temperatures (37 degrees C, 23 degrees C.) and different time intervals (0 to 120 minutes). The most conspicious changes appear to involve plasma membranes and mitochondria. Early changes (0 to 30 minutes) are mainly confined to mitochondria cristae and matrix; there is also light swelling of the endoplasmic reticulum. After 30 minutes of incubation, the majority of mitochondria have a condensed form: dense matrix and slight dilation of the cristae. These modifications are more accentuated at 75 minutes and many mitochondria are swollen and contain dense material. The modification of the membrane takes place at 30 minutes by vesiculation and/or a diffuse dilation of brush border and is followed by myelinization. The antiluminal membrane appears less sensitive but the same modification pattern appears after 75 minutes. These changes appear more slowly at 23 degrees C. than at 37 degrees C. Kinetic studies were also carried out confirming findings of various authors; cellular uptake and accumulation of 14C-glycine still take place after 2 hours of incubation. The kidney cortex slicing technique does not seem to be suitable for the study of absorption at the luminal membrane. Furthermore, our observations suggest that the generally accepted ultrastructure of some organelles does not correspond to their appearance in the noramlly functioning state in vivo.
Insights
Ultrastructural changes in kidney cortex slices were observed during incubation. Mitochondria and plasma membranes showed significant alterations, with changes occurring faster at 37°C than 23°C.
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.