Daniel R. Kapusta, Ph.D.Department of Pharmacology, LSUHSC

MEB Rm 7106568-3940; dkapus@lsuhsc.edu

Renal Transport of Sodium, Chloride and other Solutes

Total Body Sodium Balance:Input = Output

Renal excretion of sodiumRenal excretion of sodium

Renal handling of water, electrolytes and solutesRenal handling of water, electrolytes and solutes

Renal handling of sodium

Renal process involved in the production of urineRenal process involved in the production of urine

1) Glomerular filtration1) Glomerular filtration

2) Renal tubular secretion2) Renal tubular secretion

3) Renal tubular reabsorption3) Renal tubular reabsorption

Glomerular filtration

Tubular secretion

PCT organic acid secretory transport system

PCT organic base secretory transport system

Tubular filtration and reabsorption Tubular filtration and reabsorption

Average Values for Several Substances Handled by Filtration and Reabsorption

AmountFiltered Amount %

Substance per Day Excreted Reabsorbed Water, L 180 1.8 99.0 Sodium, g 630 3.2 99.5 Glucose, g 180 0 100 Urea, g 56 28 50

Segmental renal tubular sodium reabsorption

Tuboglomerular feedback regulation of sodium chloride excretion

Juxtaglomerular apparatus (JGA)

Regulation of sodium excretion –Glomerulotubular balance

Glomerulotubular balance

Transport pathways across tubular cells

Sodium, glucose and bicarbonate reabsorption in the proximal convoluted tubule

Renal tubular reabsorption of glucoseRenal tubular reabsorption of glucose

- The increase in sodium loss in the urine, a ‘natriuresis’, causes water to follow and thus produce diuresis

- Diuretics increase the rate of urine formation by interfering with the reabsorption of sodium by the nephron

- Diuretics are drugs that increase the net excretion of water from the body

“Mannitol”

CarbonicAnhydrase

CarbonicAnhydrase

Electrolyte transport pathways in the TALH

Sodium and chloride reabsorption in theearly distal convoluted tubule

Sodium - potassium exchange in the late distal convoluted tubule

AVP-dependent water permeability in the distal nephron

Vasopressin – mediated water reabsorption