Lactic dehydrogenase (LDH) isozyme patterns were examined in rats after exposing the animal to 250 "ppm of sulfur dioxide gas. The isozymes of the respective tissues were separated on cellulose- acetate strips from the brain, lung," heart, liver, kidneys, and muscle, and visualized as the isozyme bands by the formazan reaction and analyzed by densitometry.
As well as the above experiment, room-air and room-air+SO₂, were aerated through tissue homogenates in-vitro, accompanied by pure oxygen aeration in order to see the in vitro effect of the gases on the LDH activity in the tissues mentioned with the following conclusions.
(1) The H-type of LDH activity dominated in the normal heart tissue of rats, M-type in the normal lung, liver, and muscle tissues of the animal.
(2) The kidney tissue of normal rats exhibited preponderance of LDH-1 and-5 isozymes, brain tissue in LDH-1 and-4 isozymes.
(3) When rats inhaled sulfur dioxide gas in the ,concentration of 250 ppm, it .appeared that the M-type tended to predominate in the anaerobic tissues .and the H-type in the aerobic tissue.
(4) The degree of oxygen tension seemed to be correlated with the low level of LDH activity in the an-aerobic tissues such as liver and muscle and with the increased activity in the aerobic tissues, such as heart and lung.
(5) The low oxygen tension seems to favor synthesis of M-type LDH and high oxygen tesnion H-type LDH in the tissues of rats.
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