The primary determinant of the resting membrane potential

Table of Contents Show

Potassium related content
Total Body Potassium
Required Entries
Data points:
Reference
Cheng YL, Yu AW. ELECTROLYTES - Water-Electrolyte Balance: in Encyclopedia of Food Sciences and Nutrition (Second Edition), Oxford: 2003. https://doi.org/10.1016/B0-12-227055-X/00395-3.
References
What determines resting potential?
What creates the resting membrane potential?
What is the resting membrane potential of the cell membrane?

Potassium correction based on pH
Potassium Deficit Calculator
Potassium Dosing Calculator
Fractional Excretion of Potassium
Transtubular Potassium Gradient (TTKG)
Potassium Chloride: A Clinical Review
Potassium Supplements
Total Body Potassium and ECF Estimates

Background

Total Body Potassium

Key facts:

Potassium is the major intracellular cation. 98% of the total body potassium is in the intracellular compartment with only 2% located extracellularly (plasma).
The ratio of intracellular to extracellular potassium is the major determinant of the resting membrane potential. It helps establish the resting membrane potential in neurons and muscle fibers.
Potassium has very little effect on osmotic pressure unlike sodium in the ECF.
Potassium is excreted, both actively and passively, through the renal tubules, especially the distal convoluted tubule and collecting ducts.
The primary substance regulating the serum potassium concentration is aldosterone.
The daily intake of potassium in the western diet is between 80-120 mmol.
The kidney is the major route of potassium excretion, accounting for 90% of potassium loss daily. The remaining 10% is excreted through the gastrointestinal tract.
The kidney is responsible for long term potassium homoeostasis.

Potassium Content in the Body

Dependent on sex, age, and, most importantly, muscle mass which contains 60 to 75% of total body potassium.
Total body potassium estimates for normal adult women and men:
Female: approximately 40 to 45 mmol/Kg
Male: 50 to 55 mmol/kg of body weight.
Elderly: Values are 20% less (decrease in muscle mass).
Intracellular (ICF): ~2% of total body potassium.

Required Entries

Data points:

Weight:

Patient Height:

Gender:

Is the patient elderly (65 years of age or older) ?

Reference

Cheng YL, Yu AW. ELECTROLYTES - Water-Electrolyte Balance: in Encyclopedia of Food Sciences and Nutrition (Second Edition), Oxford: 2003. https://doi.org/10.1016/B0-12-227055-X/00395-3.

Potassium Content in the Body:
The total body potassium content is dependent on sex, age, and, most importantly, muscle mass (which contains 60-75% of total body potassium), and is approximately 40-45, and 50-55 mmol per kilogram of body weight for normal adult women and men, respectively. These values decrease with age and are 20% less in the elderly because of a decrease in muscle mass.

References

Aboujamous et al. Evaluation of the Change in Serum Potassium Levels after Potassium Administration. J Clin Nephrol Ren Care 2016, 2:013,
Asmar A, Mohandas R, Wingo CS. A Physiologic-Based Approach to the Treatment of a Patient With Hypokalemia. Am J Kidney Dis. 2012 September ; 60(3): 492–497.
Cohn JN, Kowey PR, et al. New guidelines for potassium replacement in clinical practice: A contemporary review by the National Council on Potassium in Clinical Practice. Arch Intern MED/VOL 160, SEP 11, 2000.
Gennari FJ. Disorders of potassium homeostasis: Hypokalemia and hyperkalemia. Crit Care Clin. 2002;18(2):273-288.
Gennari FJ. Hypokalemia. N Engl J Med. 1998;339(7):451-458.
Kamel KS, Quaggin S, Scheich A, et al. Disorders of potassium homeostasis: an approach based on pathophysiology. Am J Kidney Dis 1994;24:597–613.
Kardalas E, et al. Hypokalemia: a clinical update. Endocrine Connections (2018) 7, R135–R146.
Kim GH, Han JS. Therapeutic approach to hypokalemia. Nephron. 2002;92(suppl 1):28-32.
Lippi G, Favaloro EJ, Montagnana M, Guidi GC. Prevalence of hypokalaemia:the experience of a large academic hospital. Intern Med J. 2010;40(4):315-316.
Rastergar A, Soleimani M. Hypokalaemia and hyperkalaemia. Postgrad Med J 2001;77:759–764.
Viera AJ, Wouk N. Potassium Disorders: Hypokalemia and Hyperkalemia.Am Fam Physician. 2015;92(6):487-495.
Weiner ID, Wingo CS. Hypokalemia-consequences, causes, and correction. J Am Soc Nephrol. 1997;8(7):1179-1188.

What determines resting potential?

The resting potential is determined by concentration gradients of ions across the membrane and by membrane permeability to each type of ion.

What creates the resting membrane potential?

This voltage is called the resting membrane potential; it is caused by differences in the concentrations of ions inside and outside the cell. If the membrane were equally permeable to all ions, each type of ion would flow across the membrane and the system would reach equilibrium.

What is the resting membrane potential of the cell membrane?

The resting membrane potential of a cell is defined as the electrical potential difference across the plasma membrane when the cell is in a non-excited state. Traditionally, the electrical potential difference across a cell membrane is expressed by its value inside the cell relative to the extracellular environment.