Stimulatory and inhibitory effects of hydrogen peroxide, diamide and vitamin K-5 on sugar transport in rat soleus muscle.
The experiments examined the stimulatory effects of H2O2, diamide and vitamin K-5 on the uptake of D-[U-14C]xylose by rat soleus muscle. All three oxidants stimulated sugar transport to the same extent, which was 30-40% of the maximal stimulatory effect of insulin (0.1 U/ml). Maximum stimulation was achieved with vitamin K-5 (0.01-0.1 mM), diamide (0.3 mM) and H2O2 (5-10 mM); at these concentrations the oxidants did not affect muscle ATP levels. Cytochalasin B (5 microM) abolished oxidant-stimulated xylose uptake. Catalase (20 U/ml) abolished the stimulatory effect of H2O2, but did not affect diamide- or vitamin K-5-stimulated transport. The ability of oxidants to stimulate sugar transport in anaerobic muscle could be demonstrated in short term (30 min) experiments, where muscle contained about 50% of its original ATP, but not after 120 min, when ATP levels were depleted. Oxidant-stimulated sugar transport was diminished and even abolished at supra-optimal oxidant concentrations; at these higher concentrations muscle ATP levels were lowered. All three oxidants inhibited the stimulatory effect of 2,4-dinitrophenol on sugar transport; this effect could be demonstrated using those oxidant concentrations which induced maximal stimulation of basal xylose uptake and which did not affect muscle ATP. It is concluded that: (1) H2O2, diamide and vitamin K-5 stimulate stereospecific sugar transport in soleus muscle by some mechanism other than lowering of ATP levels; (2) stimulation of sugar transport by oxidants is an ATP-dependent process; (3) some oxidant-sensitive sulphydryl group is critically involved in the process which activates muscle sugar transport.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001391:Azo Compounds / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D003958:Diamide / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007700:Kinetics; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013012:Sorbitol / Q000378:metabolism*; D014812:Vitamin K / Q000031:analogs & derivatives* / Q000494:pharmacology; D024483:Vitamin K 3 / Q000031:analogs & derivatives*; D014994:Xylose / Q000378:metabolism*
D001391:Azo Compounds; D002352:Carrier Proteins; D003958:Diamide; D014812:Vitamin K; D013012:Sorbitol; D024483:Vitamin K 3; D000255:Adenosine Triphosphate; D014994:Xylose; D006861:Hydrogen Peroxide; C024534:vitamin k5