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Swelling of mitochondria by the platelet antiaggregating agent ticlopidine
Abstract:
Our studies on the effects of ticlopidine on mitochondrial functions led us to an intriguing observation related to its interaction with mitochondrial membranes. Liver mitochondria were isolated from Sprague-Dawley rats and assayed for swelling by spectrophotometry. When ticlopidine was added to mitochondria preincubated in an isotonic test medium, an induced-swelling activity was observed. This activity was time and concentration dependent and occurred in different isosmotic solutions. Several analogues of ticlopidine, assayed under identical conditions, produced only a minor effect. Respiratory chain inhibitors, uncouplers, ATP, and phosphate protected the mitochondria against the ticlopidine-induced swelling, whereas oligomycin did not. Comparative studies with the drugs chloramphenicol, nitroso-chloramphenicol, and salicylate (known for their association with mitochondrial injury) showed the first two to have little effect while the third one caused swelling as expected. On the other hand, oxypolarographic tests of respiring mitochondria in the presence of ticlopidine showed that the drug is not an uncoupling agent. These results indicate that the antiaggregating agent ticlopidine interacts with mitochondrial membranes causing swelling which, in turn, may alter mitochondrial permeability; however, unlike some other swelling agents, it does not act as a classical uncoupler.
Insights
The antiplatelet drug ticlopidine causes mitochondrial swelling by interacting with mitochondrial membranes. This ticlopidine-induced mitochondrial swelling may alter permeability but does not function as a classical uncoupler.
Area of Science:
- Biochemistry
- Pharmacology
- Cell Biology
Background:
- Ticlopidine is an antiplatelet agent.
- Mitochondrial dysfunction is implicated in various pathologies.
- Understanding drug interactions with mitochondria is crucial for safety and efficacy.
Purpose of the Study:
- To investigate the effects of ticlopidine on mitochondrial functions, specifically its interaction with mitochondrial membranes.
- To determine the mechanism behind ticlopidine-induced mitochondrial changes.
Main Methods:
- Isolation of liver mitochondria from Sprague-Dawley rats.
- Assay of mitochondrial swelling using spectrophotometry.
- Evaluation of ticlopidine analogues and other known mitochondrial agents.
- Oxypolarographic studies on respiring mitochondria.
Main Results:
- Ticlopidine induced mitochondrial swelling in a time- and concentration-dependent manner.
- Respiratory chain inhibitors, ATP, and phosphate protected against swelling, while oligomycin did not.
- Ticlopidine did not act as a classical uncoupling agent in oxypolarographic tests.
- Salicylate caused swelling, while chloramphenicol and nitroso-chloramphenicol had minimal effects.
Conclusions:
- Ticlopidine interacts with mitochondrial membranes, leading to swelling and potential alterations in mitochondrial permeability.
- Unlike some other agents, ticlopidine does not function as a classical uncoupler.
- These findings highlight a novel mechanism of ticlopidine's interaction with cellular components beyond its antiplatelet activity.