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[Mechanism of opiate-induced permeability of mitochondrial membranes for potassium ions]
Abstract:
Incubation of isolated rat liver mitochondria in the presence of morphine or its derivatives--methylmorphine, tecodine, ethylmorphine and nalorphine--results in disturbances of oxidative phosphorylation due to induction of permeability of mitochondrial membranes for potassium ions. The rate of state 4 respiration of rat liver mitochondria in the presence of opiates is increased only in a medium containing potassium ions. The opiates induce the efflux of K+ from deenergized mitochondria and accumulation of free fatty acids in mitochondria. However, morphine derivatives do not alter the permeability for potassium and electrical conductibility of artificial phospholipid membranes. It was suggested that opiates cause a formation of the potassium carrier in mitochondria by releasing Ca2+, which activate phospholipase A2. The effect of opiates increases with the increase of their hydrophobic properties.
Insights
Morphine and its derivatives disrupt mitochondrial function by increasing potassium ion permeability, affecting oxidative phosphorylation. This effect is linked to opiate hydrophobicity and calcium release.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Context:
- Mitochondria are crucial for cellular energy production through oxidative phosphorylation.
- Opiates, commonly used analgesics, can have diverse cellular effects beyond their known receptor interactions.
Purpose:
- To investigate the impact of morphine and its derivatives on mitochondrial function, specifically oxidative phosphorylation.
- To elucidate the mechanism by which opiates affect mitochondrial membranes and ion transport.
Summary:
- Morphine and its derivatives induce potassium ion (K+) permeability in isolated rat liver mitochondria, disrupting oxidative phosphorylation.
- This disruption is evidenced by increased state 4 respiration in the presence of K+ ions and subsequent K+ efflux from mitochondria.
- Opiates also lead to the accumulation of free fatty acids within mitochondria, suggesting membrane damage or altered lipid metabolism.
Impact:
- The findings suggest a novel, non-receptor-mediated mechanism for opiate toxicity at the mitochondrial level.
- Understanding this mechanism could inform the development of safer analgesics or strategies to mitigate opiate side effects.
- The study highlights the role of mitochondrial membrane integrity and ion transport in cellular response to pharmacological agents.