INTRODUCTION

A. Intracellular and Interstitial Distribution

1. Concentration of dissolved substances

Example: Mammalian Nerve or Skeletal Muscle Cell

	Interstitial	Intracellular	Units
Na+ (sodium	145	10	mM/liter
Cl- (chloride)	110	5.5	mM/liter
K+ (potassium)	5	155	mM/liter
Protein-	1	35	g/dl (grams/100ml)
Glucose	5 (90)	low	mM/l (mg/dl)

Notes:

Intracellular fluid: fluid within the cell (ICF); part of the cytoplasm

Interstitial fluid: fluid in the interstitial space surrounding the cell (part of "extracellular" fluid (ECF); generally similar to blood plasma except less plasma protein)

mM/l = millimoles/liter
gm/dl = grams/deciliter (or grams/100 ml or grams%)
mg/dl = milligrams/deciliter
mV = millivolts (0.001 volt)
Vm = membrane electrical potential (intracellular)

2. Electrical charges

Inside of the cell is generally negative relative to the outside of the cell

Intracellular electrical potential (Vm) typically -70 to -80 millivolts (mV)

Note: The sign of the potential (+ or -) always referes to the inside of the cell

3. Unexpected, because concentration and electrical gradients would be expected to dissipate spontaneously

4. Concentration and electrical differences associated with cell vitality