Figure 186

Protein metabolism in acute renal failure (ARF): impairment of cellular amino acid transport. A, Amino acid transport into skeletal muscle is impaired in ARF [10]. Transmembranous uptake of the amino acid analogue methyl-amino-isobutyrate (MAIB) is reduced in uremic tissue in response to insulin (muscle tissue from uremic animals, black circles, and from sham-operated animals, open circles, respectively). Thus, insulin responsiveness is reduced in ARF tissue, but, as can be seen from the parallel shift of the curves, insulin sensitivity is maintained (see also Fig. 18-14). This abnormality can be linked both to insulin resistance and to a generalized defect in ion transport in uremia; both the activity and receptor density of the sodium pump are abnormal in adipose cells and muscle tissue [11]. B, The impairment of rubidium uptake (Rb) as a measure of Na-K-ATPase activity is tightly correlated to the reduction in amino acid transport. (From [10,11]; with permission.)

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