An Acute Infusion of Lactic Acid Lowers the Concentration of Potassium in Arterial Plasma by Inducing a Shift of Potassium into Cells of the Liver in Fed Rats

Abstract

Background: Potassium (K⁺) input occurs after meals or during ischemic exercise and is accompanied by a high concentration of L-lactate in plasma (P_L-lactate). Methods: We examined whether infusing 100 µmol L-lactic acid/min for 15 min would lead to a fall in the arterial plasma K⁺ concentration (P_K). We also aimed to evaluate the mechanisms involved in normal rats compared with rats with acute hyperkalemia caused by a shift of K⁺ from cells or a positive K⁺ balance. Results: There was a significant fall in P_K in normal rats (0.25 mM) and a larger fall in P_K in both models of acute hyperkalemia (0.6 mM) when the P_L-lactate rose. The arterial P_K increased by 0.8 mM (p < 0.05) 7 min after stopping this infusion despite a 2-fold rise in the concentration of insulin in arterial plasma (P_Insulin). There was a significant uptake of K⁺ by the liver, but not by skeletal muscle. In rats pretreated with somatostatin, P_Insulin was low and infusing L-lactic acid failed to lower the P_K. Conclusions: A rise in the P_L-lactate in portal venous blood led to a fall in the P_K and insulin was permissive. Absorption of glucose by the Na⁺-linked glucose transporter permits enterocytes to produce enough ADP to augment aerobic glycolysis, raising the P_L-lactate in the portal vein to prevent postprandial hyperkalemia.

Increasing plasma [K+] by intravenous potassium infusion reduces NCC phosphorylation and drives kaliuresis and natriuresis

“…However, when the same amount of potassium was infused into the stomach along with a K ϩ -free meal, a significant kaliuresis ensued although there was no significant rise in plasma K ϩ , providing evidence for feed-forward regulation of K ϩ excretion (29). The regulation of K ϩ distribution between ECF and ICF, an important parameter not directly addressed in this study, can be affected by insulin, catecholamines, plasma K ϩ itself, and lactic acid production (4,6,45).…”

Regulation of the Renal NaCl Cotransporter and Its Role in Potassium Homeostasis

“…As food usually contains both glucose and K ϩ , the glucose-induced release of insulin not only facilitates the cellular uptake of glucose but also of K ϩ (246). Absorption of dietary glucose will also increase plasma L-lactate levels, which contributes to a shift of K ϩ into hepatocytes (48). During prolonged fasting, the activity of the Na ϩ -K ϩ -ATPase is inhibited, such that there is a net efflux of K ϩ ions from the intracellular to the extracellular compartment.…”

Bolus Administration of Intravenous Glucose in the Treatment of Hyperkalemia: A Randomized Controlled Trial

“…This approach of using endogenously secreted insulin to shift K + into cells is supported by data from a recent paper by Cheema-Dhadli et al [34], who studied the effects of an infusion of L -lactic acid on K + shift in rats. They demonstrated that the liver plays a major role in removing absorbed dietary K + from the portal blood, thereby minimizing the risk of cardiac arrhythmia which might result if blood with a high serum K + concentration were delivered to the heart.…”