PMID- 10993639
OWN - NLM
STAT- MEDLINE
DCOM- 20000928
LR  - 20240109
IS  - 0955-3002 (Print)
IS  - 0955-3002 (Linking)
VI  - 76
IP  - 9
DP  - 2000 Sep
TI  - Differential modification by caffeine of oxygen-dependent and independent effects 
      of gamma-irradiation on rat liver mitochondria.
PG  - 1281-8
AB  - PURPOSE: Following the demonstration that caffeine effectively competes with 
      oxygen for electrons and also scavenges hydroxyl radicals and singlet oxygen, the 
      differential modification of oxygen-dependent and independent effects of 
      gamma-radiation by caffeine in membranes was examined, using rat liver 
      mitochondria as a model system. MATERIALS AND METHODS: Mitochondria were isolated 
      from the livers of Wistar rats and exposed to gamma-radiation in the dose range 
      of 45-600 Gy (dose rate 15 Gy/min) in the presence or absence of caffeine. To 
      examine the 'oxygen effect', post-irradiation incubation was carried out in the 
      presence of oxygen or nitrogen in buffers saturated with the respective gases. 
      Membrane damage was examined as lipid peroxidation (assessed as formation of 
      thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides (LOOH) and 
      conjugated dienes (CD), protein oxidation, depletion of protein thiols, 
      superoxide dismutase or glutathione. RESULTS: Lipid peroxidation increased as a 
      function of radiation dose, from 45 to 600 Gv. Post-irradiation incubation of 
      mitochondria under nitrogen decreased the response, while incubation under oxygen 
      saturation enhanced it significantly. The presence of caffeine during radiation 
      exposure inhibited lipid peroxidation significantly as a function of 
      concentration, in the range of 5 microM to 4 mM. The inhibition was highest with 
      4 mM of caffeine. Under oxic conditions, inhibition at 1 mM was significantly 
      more than under anoxia. Anoxia was either ineffective or marginally increased 
      peroxidation in the presence of caffeine. A similar observation was obtained when 
      membrane damage was assessed as protein oxidation. Radiation-induced depletion of 
      protein thiols was greatly enhanced by oxygen saturation and this was completely 
      prevented by caffeine. This compound also protected against the radiation-induced 
      loss of the antioxidant glutathione and the enzyme superoxide dismutase. 
      CONCLUSIONS: The results suggest that caffeine effectively protected membranes 
      against the oxic component of damage but may not do so for the anoxic component.
FAU - Kamat, J P
AU  - Kamat JP
AD  - Cell Biology Division, Bhabha Atomic Research Centre, Mumbai, India.
FAU - Boloor, K K
AU  - Boloor KK
FAU - Devasagayam, T P
AU  - Devasagayam TP
FAU - Jayashree, B
AU  - Jayashree B
FAU - Kesavan, P C
AU  - Kesavan PC
LA  - eng
PT  - Journal Article
PL  - England
TA  - Int J Radiat Biol
JT  - International journal of radiation biology
JID - 8809243
RN  - 0 (Free Radicals)
RN  - 0 (Phosphodiesterase Inhibitors)
RN  - 0 (Sulfhydryl Compounds)
RN  - 0 (Thiobarbituric Acid Reactive Substances)
RN  - 3G6A5W338E (Caffeine)
RN  - EC 1.15.1.1 (Superoxide Dismutase)
RN  - N762921K75 (Nitrogen)
RN  - S88TT14065 (Oxygen)
SB  - IM
MH  - Animals
MH  - Caffeine/*pharmacology
MH  - Dose-Response Relationship, Radiation
MH  - Free Radicals/radiation effects
MH  - *Gamma Rays
MH  - Lipid Peroxidation/radiation effects
MH  - Male
MH  - Mitochondria, Liver/*drug effects/*radiation effects
MH  - Nitrogen/metabolism
MH  - Oxidative Stress/radiation effects
MH  - Oxygen/*metabolism
MH  - Phosphodiesterase Inhibitors/pharmacology
MH  - Radiation Tolerance
MH  - Rats
MH  - Rats, Wistar
MH  - Sulfhydryl Compounds/metabolism
MH  - Superoxide Dismutase/metabolism
MH  - Thiobarbituric Acid Reactive Substances/metabolism
EDAT- 2000/09/19 11:00
MHDA- 2000/09/30 11:01
CRDT- 2000/09/19 11:00
PHST- 2000/09/19 11:00 [pubmed]
PHST- 2000/09/30 11:01 [medline]
PHST- 2000/09/19 11:00 [entrez]
AID - 10.1080/09553000050134519 [doi]
PST - ppublish
SO  - Int J Radiat Biol. 2000 Sep;76(9):1281-8. doi: 10.1080/09553000050134519.