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Updated: Sep 6, 2026
An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment
Published on: December 3, 2020
Abstract:
The effect of trypsin on the morphology of the rat liver microsomal fraction isolated by differential centrifugation has been investigated. The microsomes were incubated at 37 degrees C and centrifuged thereafter under the conditions of their initial isolation. The trypsin-treated microsomes and the untreated controls were fixed in unbuffered osmium tetroxide and embedded first in gelose and then in methacrylate. In the trypsin-treated microsomes, there was a removal of the ribosomes from the rough vesicles. Parallel chemical determinations showed that the total nitrogen and total phosphorus of the pellet were lowered. Particles, densely stained with phosphotungstic acid (PTA) and homogeneous in appearance, were found within microsome smooth vesicles in a fluffy layer which collects on the top of the microsome pellet. The morphology of these PTA-stained particles remained unchanged after incubation with trypsin.
Insights
Trypsin treatment removes ribosomes from rat liver microsomes, altering their structure. Specific PTA-stained particles within smooth vesicles remained unaffected by this enzymatic digestion.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Rat liver microsomes are crucial for cellular processes.
- Understanding microsomal structure is key to cellular function.
- Enzymatic digestion can reveal structural components.
Purpose of the Study:
- To investigate the effect of trypsin on rat liver microsomes.
- To analyze morphological changes induced by trypsin.
- To identify trypsin-resistant structures within microsomes.
Main Methods:
- Isolation of rat liver microsomes via differential centrifugation.
- Incubation of microsomes with trypsin at 37°C.
- Electron microscopy using osmium tetroxide fixation and methacrylate embedding.
- Phosphotungstic acid (PTA) staining for particle visualization.
- Chemical analysis of total nitrogen and phosphorus.
Main Results:
- Trypsin treatment led to the removal of ribosomes from rough microsomal vesicles.
- Chemical analysis indicated a decrease in total nitrogen and phosphorus content.
- Homogeneous, PTA-dense particles were observed within smooth vesicles.
- These PTA-stained particles showed no morphological changes after trypsin incubation.
Conclusions:
- Trypsin effectively removes ribosomes from rat liver microsomes.
- Specific internal structures (PTA-dense particles) are resistant to trypsin digestion.
- These findings contribute to understanding microsomal composition and stability.
