Reduction of erythrocyte (Na+-K+)ATPase activity in Type 1 (insulin-dependent) diabetic subjects and its activation by homologous plasma

Abstract

The (Na+-K+)ATPase and (Mg2+)ATPase activities of erythrocyte membranes of Type 1 (insulin-dependent) diabetic patients were found to be significantly reduced compared to matched controls (p less than 0.005). On the contrary, erythrocyte Na+ and K+ contents were similar in diabetic patients and in normal subjects. When erythrocyte membranes from diabetic patients were incubated with their own plasma, a significant increase was observed in sodium-potassium ATPase activity (p less than 0.005), whereas (Mg2+)ATPase activity was not affected. The plasma stimulatory effect showed saturation kinetics. Maximum average stimulation was 96% (+/- 21.3). A similar stimulation pattern, although more limited in extent (maximum 48.3% +/- 12.2), was found when erythrocyte membranes from normal subjects were incubated with diabetic plasma. Normal plasma exhibited a modest stimulatory effect on erythrocyte (Na+-K+)ATPase activity. Similar stimulatory effects by diabetic plasma were observed on a (Na+-K+) ATPase preparation from beef heart. It is proposed that diabetic plasma contains a specific (Na+-K+)ATPase activator in a higher concentration than normal plasma. This may explain why a normal cellular electrolyte content was found in diabetic erythrocytes in spite of a reduced Na+-K+ pump activity. Purification experiments indicate that the plasma activator is a protein with a molecular weight greater than 50,000. Both the (Na+-K+)ATPase activity and the stimulatory effect of diabetic plasma were not influenced by the metabolic control, since they did not correlate significantly with fasting blood glucose and daily insulin dosage. Moreover, no correlation was found with duration of diabetes or age at diagnosis of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocyte Na/K ATPase activity and diabetes: relationship with C-peptide level

“…In this study, we confirmed our previous finding [3,4,5,6] that diabetic neuropathy is associated with lower erythrocyte Na/K ATPase in Type I diabetic patients. The same finding was also observed in Type II diabetic patients.…”

Influence of <i>Cardiospermum halicacabum</i> leaf extract on membrane-bound ATPases in streptozotocin-induced diabetic rats

“…We have previously demonstrated that the cardiospermum halicacabum leaf extract (CHE) is having antihyperglycaemic, antioxidant, antiglycation and antihyperlipidemic activity on STZ-induced diabetic rats (Veeramani et (Finotti and Palatini, 1986). Hence, the present study we observed that the decrease activity of Na + /K + -ATPase may be considered as an index of cardiovascular complications induced by diabetes.…”

Association of diabetic neuropathy with Na/K ATPase gene polymorphism

“…In patients with IDDM, we and others [12][13][14][15][16] have reported depressed Na/K ATPase activity in erythrocyte membranes; this decrease probably reflects a decrease in nerve tissue. In this regard we showed a parallel decrease of Na/K ATPase activity in both erythrocytes and sciatic nerve of diabetic rats [17].…”

“…This transport not only maintains sodium and potassium concentration gradients between the intracellular and extracellular milieus, but is also critical to a number of important processes including membrane potential generation and nerve conduction [11]. A decrease in Na/K ATPase activity has been reported in the erythrocytes of IDDM patients and diabetic rats [12][13][14][15][16][17]. Moreover, the impairment of this enzyme activity is proportional in sciatic nerve and erythrocytes of diabetic rats [17].…”