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KMID : 0378019700130010039
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New Medical Journal
1970 Volume.13 No. 1 p.39 ~ p.45
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Oxidative Metabolism of C^(14)-acetate in Various Tissues of Rabbits
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Abstract
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Tissue homogenates of brain, kidney, liver, heart and bone of rabbits were incubated in media in which C14-acetate were added so as to maintain concentration of acetate 5, 10, 20, 40, 50 and 60mg %.
After 3 hrs incubation period, CO2 sample released from tissue homogenates were analyzed fpr their total CO2 production rate and radioactivities.
Relative specific activities were determined by ratios between specific activities of CO2 and medium C14-acetate and calculated CO2 yield from medium C19-acetate. From the concentrations of medium C14acetate COz yield from acetate curve, Km for the multienzyme system partisipated in acetate-CO2 reaction were determined for chemical kinetic analysis of oxidative metabolism of various tissues.
The results were as, follows:
1. In every tissue, total CO2 production rates, RSA and CO2 yield from acetate were increased abruptly at low concentration of medium C14-acetate and reach to maximum plateau value at high concentration of medium acetate representing kinetic characteristics of enzyme reaction.
2. The concentration which start to appear the plateau values were 10mg% in brain tissue, 20mg% in liver and kidney and 40mg% in the heart tissue.
3. Total CO2 production rates of each tissue which were compared at maximum plateau value were 22. 4 in brain, 16.3 in kidney, 8.5 in heart, 7.6 in liver and 2.04 pM/hr/gm in bone tissue. On the other hand maximum plateau values of RSA of various tissues were 45.2 in heart, 29.4 in kidney, 9.5 in brain and 2.2% in liver and bone tissue. Appreciable amount of acetate was participate to oxidative metabolism in heart and kidney but participations of acetate on oxidative metabolism were negligible in other tissues.
4. Km for multienzyme system related to acetate-CO2 were 1.75X10-´ in brain and kidney, 3.25X10-´ in heart, 3.08 X 10-4 in liver and 0. 66 X 10-4M/l in bone tissue. These data showed to reach more easily maximum velocity at low concentration of medium C14-acetate in the bone tissue than in other.
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