Chloride

Chloride

Introduction

• Most abundant anion in extracellular fluid– 88% found extracellularly– 12% found intracellulary

• Often associated with sodium• Total body content: 0.15% of body weight– 105 g in 70 kg human

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Nomenclature and Forms

• Diatomic molecule chlorine (Cl2) when in natural form

• Exists as an ion (Cl-) when inside the body• Forms various salts and compounds via

covalent bonding

History

• 1774: Gaseous element first produced by Carl Wilhelm Scheele

• 1807: Sir Humphry Davy correctly identified Scheele’s discovery as a new element, chlorine

Royal Society of Chemistry. Visual Elements Periodic Table. Accessed from http://www.rsc.org/periodic-table. 2013.

Unit of Measure

• In serum: mEq/ L chloride• In foods: mg

Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.

Food Sources

• Average consumption: 50 – 200 mEq Cl/ day• Primary source: salt in food (60% chloride)• Other sources:– Soy sauce– Fresh meats, seafood, milk, eggs– Large amounts in processed foods

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Thompson JL, Manore MM, Vaughan LA. The science of nutrition. Illinois: Pearson Education, Inc. 2008.Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.

Digestion, Absorption, Transport, and Excretion

• Majority of dietary chloride is absorbed in the small intestine

• Regulated by the kidneys– Conserved by reabsorption in renal tubules– Enhanced by aldosterone

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Thompson JL, Manore MM, Vaughan LA. The science of nutrition. Illinois: Pearson Education, Inc. 2008.

Digestion, Absorption, Transport, and Excretion

• Absorption closely follows that of sodium but with different mechanisms– Cl passively follows Na through paracellular (tight

junction) pathway– Absorbed Na creates electrical gradient that

provides energy for inward diffusion of Cl

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Digestion, Absorption, Transport, and Excretion

Stipanuk MH. Biochemical, physiological, and molecular aspects of human nutrition, 2nd ed. Missouri: Saunders Elsevier. 2006.

Digestion, Absorption, Transport, and Excretion

• Excreted through three primary routes– Gastrointestinal tract– Skin– Kidneys

• Losses closely reflect those of sodium

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Digestion, Absorption, Transport, and Excretion

Stipanuk MH. Biochemical, physiological, and molecular aspects of human nutrition, 2nd ed. Missouri: Saunders Elsevier. 2006.

Digestion, Absorption, Transport, and Excretion

• Major secretory product of stomach• Mechanism: electrogenic chlorine secretion– Only ion actively secreted by epithelium– Cells take up Cl from blood across basolateral

membrane via Na+/K+/Cl- cotransport pathway– Gradient set up by Na+/K+-ATPase pump– Cl accumulating in cells exit through brush border

membrane into lumen (using Cl channels)

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Digestion, Absorption, Transport, and Excretion

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Functions and Mechanisms of Action

• Major anion of extracellular fluid– Mostly in association with sodium– Associates with potassium inside cells– Maintains fluid and electrolyte balance

• Aids in preparing food for digestion (as HCl)– Maintain acid-base balance– Activation of pepsinogen to pepsin– Breakdown of protein

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Thompson JL, Manore MM, Vaughan LA. The science of nutrition. Illinois: Pearson Education, Inc. 2008.Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.

Functions and Mechanisms of Action

• Helps kill bacteria– Released by white blood cells during phagocytosis

• Assists in transmission of nerve impulses• Role in enzyme inactivation• Interactions with macroions– Surfaces are modified by counterion atmosphere

enriched with oppositely charged small ions

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Thompson JL, Manore MM, Vaughan LA. The science of nutrition. Illinois: Pearson Education, Inc. 2008.Stipanuk MH. Biochemical, physiological, and molecular aspects of human nutrition, 2nd ed. Missouri: Saunders Elsevier. 2006.

Functions and Mechanisms of Action

• Acts as exchange anion for HCO3- in red blood

cells (chloride shift)– Requires protein transporter that moves Cl and

HCO3 ions in opposite directions

– Allow transport of tissue-derived CO2 back to lungs in the form of plasma HCO3

-

– Waste CO2 from tissue is converted to HCO3- by

carbonic anhydrase

Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Interactions with Other Nutrients

• Sodium– Maintains osmolarity and balances in fluid,

electrolytes, and acid-base interactions– Negative charge of Cl neutralizes positive charge

of Na– Use similar pathways for absorption and transport

(electrochemical gradient from Na is needed)• Potassium– Associates when inside cells

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Stipanuk MH. Biochemical, physiological, and molecular aspects of human nutrition, 2nd ed. Missouri: Saunders Elsevier. 2006.

Recommended Nutrient Intakes

Age Weight (kg) Chloride (mg)

Month

• 0 – 5• 6 - 11

• 4.5• 8.9

• 180• 300

Year

• 1• 2 – 5• 6 – 9• 10 – 18• > 18

• 11• 16• 25• 50• 70

• 350• 500• 600• 750• 750

Food and Nutrition Research Institute. Recommended energy and nutrient intakes: Philippines, 2002 edition. Bicutan: Department of Science and Technolgy. 2002.

Assessment of Nutriture

• Usual serum concentration: 101-111 mEq/ L• Concentration depends on body water status• Two techniques widely used:– Ion-selective electrode potentiometry– Coulometric titration with silver ions

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.

Deficiency

• Diets rarely lack chloride• Occurs chiefly through gastrointestinal tract

disturbance– Heavy sweating– Chronic diarrhea– Prolonged vomiting– Severe dehydration

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.

Deficiency

• Can lead to alkalosis– Excessive loss of chloride ions from gastric

secretion– During continued vomiting, diarrhea, or tube drain– Concentration of bicarbonate ions in plasma are

increased– Main symptom: muscle convulsions

Claudio VS, Dirige OV, Ruiz AJ. Basic nutrition for Filipinos, 5th ed. Manila: Merriam & Webster Bookstore, Inc. 2004.Gropper SS, Smith JL, Groff JL. Advanced nutrition and human metabolism, 5th ed. California: Wadsworth Cengage Learning. 2009.Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.

Toxicity

• No known toxicity symptoms for chloride alone– Vomiting– Hypertension (for salt-sensitive individuals)

• High blood chloride concentration can be caused by dehydration due to water deficiency

Thompson JL, Manore MM, Vaughan LA. The science of nutrition. Illinois: Pearson Education, Inc. 2008.Whitney E, Rolfes SR. Understanding nutrition, 10th ed. California: Thomson Learning, Inc. 2005.