Insulin potassium uptake

Il.f.l.1. Insulins. Insulin is the most effective of diabetes medications. Insulin has profound effects on carbohydrate, protein, fat metabolism and electrolytes. It has anabolic and anticatabolic actions. In a state of insulin deficiency, glycogenesis, glucose transport, protein synthesis, triglyceride synthesis, LPL activity in adipose tissue, cellular potassium uptake all decrease on the other hand, gluconeogene-sis, glycogenolysis, protein degradation, ketogene-sis, lipolysis increase. 

Glucose insulin potassium (GIK) infusion has been suggested by some to offer additional myocardial salvage in the setting of an acute Ml. Theoretically, GIK infusion provides glycolytic fuel to both the starving ischemic myocardium before intervention and the reperfused myocardium after PCI. It is also thought to decrease free fatty acid (FFA) levels and toxic FFA uptake by the ischemic myocardium. 

Increases in plasma potassium are sufficient to stimulate insulin release into the portal circulation (DeFronzo 1992). Insulin stimulates potassium uptake by the liver... 

Insulin is an endogenous hormone produced by fi-cells of islets of Langerhans of the pancreas, which consist of two chains of amino acids. It is required to be administered by a parenteral routes as it is destroyed when given orally. Insulin is used for the control of IDDM and in the emergency management of diabetic ketoacidosis.30 Insulin promotes the intracellular uptake of potassium and is used in hyperkalemia. Baker et al.31 have used insulin and glucagon in the treatment of liver disorders. Recent evidence indicates that the effects of insulin with glucose and potassium in ischemic heart disease have proved beneficial.32 It also is used in acute myocardial infarction.32... 

In a starved patient, the secretion of insulin is decreased in response to the low carbohydrate intake. Catabolised fats and protein are used for energy. This results in an intracellu+llar loss of electrolytes, in particular phosphates. When the patient starts to feed, a sudden shift from fat to carbohydrate metabolism occurs and secretion of insulin increases. This stimulates cellular uptake of magnesium, phosphate and potassium, which can lead to hypophosphataemia,... 

The small fraction (2%) of the total body pt)tassium which is in the extracellular compartment is distributed proportionately between the interstitial and plasma spaces. The concentration in serum is around 4.5 mmol/l. Whereas serum potassium concentration does not vary appreciably in response to water loss or retention, factors which cause even a small or sudden shift of intracellular potassium will cause a big change in the ECF potassium content and concentration. Cellular uptake of potassium is stimulated by insulin. Of particular im wrtance is the reciprocal relationship between potassium and hydrogen ions. Many hydrogen ions are buffered inside cells. As the concentration of hydrogen ions increases with the development of acidosis, potassium ions arc displaced from the cell in order to maintain... 

When insulin is administered to patients with untreated diabetes mellitus, potassium moves quickly into cells and the patient rapidly becomes hypokalemic. Large amounts of serum potassium can be lost due to diarrhea or to the use of laxatives and increased uptake of potassium into cells by increased catecholamines (via activation of (Ij receptors) or insulin (Stein and Zeusem 1992, Peterson and Levi 1996). 

B. Insulin. Blood glucose is lowered directly by the stimulation of cellular uptake and metabolism of glucose. Cellular glucose uptake Is accompanied by an intracellular shift of potassium and magnesium. Insulin also promotes glycogen formation and lipogenesis. 

Potassium concentration in plasma is dependent on renal function and acid-base balance. Mineral-ocorticoids promote the renal excretion of potassium, and insulin favors cellular uptake (Table 5). 

The second question concerns the fact that insulin action involves not only effects on glucose uptake, but other effects such as changes in phosphate turnover (Stadie, 1954) and the cellular accumulation of potassium (Verzdr, 1952), as well as effects on protein synthesis (Bouckaert and de Duve, 1947). Are these changes simply the secondary consequence of a primary insulin action upon cell permeability to glucose We do not know. Despite the appeal of a single unitary mechanism for insulin action, the possibility of direct effects of insulin on events other than glucose transfer cannot be ruled out. 

Insulin is a powerful positive inotropic drug. It increases the cardiac output and HR due to increased catecholamine discharge and calcium uptake by heart cells. Insulin reduces plasma potassium levels, thereby increasing cellular transmission and automaticity [32]. The first reported case of a pahent with acute propafenone poisoning and treatment with high-dose insulin and glucose ... 

Diabetes—Uncontrolled diabetes is frequently accompanied by acidosis and ketosis-conditions characterized by excesses of acid and ketones in the blood— which may lead to depletion of bone calcium and of muscle potassium. It is noteworthy that the treatment of diabetes with insulin results in the rapid uptake of bloodborne potassium by the tissues. Hence, there may be a dangerous drop in the blood level of this mineral, unless extra amounts are given. 

The uptake of potassium by muscle exposed to insulin is amenable to interpretation since Zierler (1959) has demonstrated hyperpolarization of the cell membrane under such circumstances, whether or not glucose was present during incubation the Mine was observed with adipocytes (Beigelman and Hollander, 1963). Hyperpolarization of cell membrane induced by insulin might in turn result from enhanced active sodium transport from the cytoplasm outward, as has been shown by Moore (1965) to occur in the case of frog sartorius. 

Randle, P. J., and Smith, G. H., 1958, Regulation of glucose uptake by muscle. 1. The effects of insulin, anaerobiosis and cell poisons on the uptake of glucose and release of potassium by isolated rat diaphragm, Biochem. ]. 70 490. 

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