Effects of Thiamine Deficiency and of Oxythiamine on Rat Tissue Transketolase

Abstract

Transketolase activity varied markedly in different rat tissues. When listed in the order of decreasing activity per gram of fresh tissue they were liver, kidney, spleen, intestine, lung, brain, heart, erythrocytes and muscle. The transketolase activity of all of the rat tissues tested with the exception of brain was decreased by thiamine deficiency. In heart tissue this effect was evident after 4 experimental days, and in all tissues (but brain) by 7 days; the effect was greater in the affected tissues after 13 days of thiamine deficiency. In lung, erythrocytes, kidney, and intestine the enzyme was depressed to about one-third of normal activity; in spleen, heart and liver it was depressed to about one-half of normal activity, and in muscle it was depressed to about four-fifths of normal activity after 13 experimental days of thiamine deficiency. Brain transketolase was unaffected in these rats. Oxythiamine, when administered daily at a level of 100 µg/rat for 13 days by intraperitoneal injection resulted in decreased transketolase activity in all the tissues tested with the exception of brain, whether administered to thiamine-adequate or to thiamine-deficient rats. Neither thiamine deficiency nor the administration of oxythiamine to thiamine-adequate or thiamine-deficient rats resulted in adverse effects on growth, appearance, or behavior during the 13-day experimental period. These studies lend support to the belief that the effect of thiamine deficiency on decreasing erythrocyte transketolase, a tissue readily available from the host without detriment, is a reflection of the thiamine adequacy of other tissues, particularly in a marginal deficiency.