Reduction of erythrocyte (Na(+)-K+) ATPase activities in non-insulin-dependent diabetic patients with hyperkalemia.
To elucidate the mechanism of hyperkalemia in diabetic patients without renal failure, we investigated (Na(+)-K+) adenosine triphosphatase (ATPase) activity in erythrocyte membrane, erythrocyte Na+ and K+ content, and plasma endogenous digitalis-like substance in control subjects (n = 16) and non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 62). NIDDM patients were divided into normokalemic patients (NKDM, n = 48) and hyperkalemic patients (HKDM, n = 14). There was no difference in plasma glucose or hemoglobin A1c (HbA1c) levels, plasma renin activity (PRA), and plasma aldosterone concentrations (PAC) between NKDM and HKDM patients. (Na(+)-K+)ATPase activities in NIDDM patients were significantly reduced compared with those in control subjects (0.336 +/- 0.016 mumol-inorganic phosphate [Pi]/mg protein/h, mean +/- SEM, P less than .05), and (Na(+)-K+)ATPase activities in HKDM patients (0.243 +/- 0.015 mumol Pi/mg protein/h) were significantly reduced compared with those in NKDM patients (0.295 +/- 0.008 mumol Pi/mg protein/h, P less than .01). Plasma K+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in diabetic patients (r = -.365, P less than .01). Erythrocyte Na+ content had a significant negative correlation with (Na(+)-K+)ATPase activity in control subjects (r = -.619, P less than .05). There was no difference in plasma endogenous digitalis-like substance among the three groups. (Na(+)-K+)ATPase activity was not significantly correlated with plasma endogenous digitalis-like substance in control subjects and diabetic patients. These findings suggest that the reduction of (Na(+)-K+)ATPase activity, which was not related to plasma digitalis-like substance, may be partly responsible for hyperkalemia in diabetic patients.
Mimura
M
M
Second Department of Internal Medicine, Chiba University, School of Medicine, Japan.
Makino
H
H
Kanatsuka
A
A
Yoshida
S
S
D000328:Adult; D017301:Ca(2+) Mg(2+)-ATPase / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000097:blood / Q000150:complications* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D012016:Reference Values; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*
D012964:Sodium; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium