On the stimulation of rat thymocyte 3-0-methyl-glucose transport by mitogenic stimuli
✍ Scribed by David A. Hume; Maurice J. Weidemann
- Publisher
- John Wiley and Sons
- Year
- 1978
- Tongue
- English
- Weight
- 486 KB
- Volume
- 96
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Abstract
Pretreatment of rat thymus lymphocytes with N‐ethyl‐maleimide prevents the stimulation of 3‐0‐methyl‐glucose transport by concanavalin A or ionophore A23187 but does not affect the ability of concanavalin A to induce a rapid increase in cellular Ca^2+^ uptake. N‐ethyl‐maleimide added after concanavalin A amplifies rather than prevents the subsequent stimulation of 3‐0‐methyl‐glucose transport. Incubation of thymocytes with concanavalin A produces a decrease of 43% in the apparent K~i~ for phloretin, a competitive inhibitor of 3‐0‐methyl‐glucose transport, without affecting the apparent K~m~ for the substrate. Similarly, very low concentrations of cytochalasin B inhibit concanavalin A‐stimulated glucose transport preferentially, without markedly affecting the unstimulated transport rates. The similarity between concanavalin A‐stimulated 3‐0‐methyl‐glucose transport in thymocytes and insulin‐stimulated glucose transport in adipose tissue, with particular emphasis on the effects of the modifying agents described in this paper, is discussed.