Effect of insulin on pyruvate dehydrogenase in a mixture of plasma membranes and mitochondria from normal and alloxan treated rat brains.
In a mixture of plasma membranes/mitochondria from normal rat brain, pyruvate dehydrogenase (PDH) is present in the active (PDHa) and the inactive (PDHi) form; the latter is converted into the former by preincubation with Ca2+ and Mg2+ and represents about 40% of total PDH (PDHt = PDHa + PDHi). Incubation with increasing insulin concentrations activates PDHa and PDHt, the maximum being reached at 25 microU/ml insulin; inhibition appears with further insulin increase. In a mixture of plasma membranes and mitochondria from alloxan rat brain PDHa activity markedly decreases; no activation is achieved by preincubation with Ca2+ and Mg2+. However an activating effect of Ca2+ and Mg2+ appears when the mixture is added and incubated with increasing insulin concentrations. PDHa and PDHt activity reaches a maximum of stimulation at 25 microU/ml insulin; the activation is reduced at higher concentrations of insulin though no inhibition appears. ATP partially inhibits PDHa in normal and alloxan rat brain plasma membrane/mitochondria mixtures; this effect is completely cancelled by 25 microU/ml insulin.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*; D051381:Rats
D007328:Insulin; D011768:Pyruvate Dehydrogenase Complex