Table 1.
Electrical characteristics of some epithelia and endothelia
| Tissuesa | Species | Rcell Ω × cm2 | Rparacellular Ω × cm2 | PNa/PClb |
|---|---|---|---|---|
| Proximal tubule | dog | – | 6–7 | 1.4 |
| Gallbladder | rabbit | 229 | 21 | 3.3 |
| Duodenum | rat | – | 98 | – |
| Jejunum | rat | 67 | 51 | 10.0 |
| Ileum | rabbit | 115 | 100 | 2.5 |
| Distal colon | rabbit | 730 | 385 | 0.6 |
| mouse surface | 132 | 3,200 | – | |
| crypt | 429 | – | – | |
| Brain endothelium | 1,300 | |||
| Gastric fundus | Necturus | 2,826 | 10,573 | – |
| Urinary bladder | rabbit | 160,000 | 300,000 | – |
| Cell linesc | ||||
| Caco-2 | human colon | 125–250 | – | 3.0 |
| LLC-PK1 | pig prox. tubule | 100 | – | 0.6 |
| MDCK | dog | 60–4000 | – | 10.0 |
aAll values can be found in Powell (Powell 1981) or Crone (Crone and Christensen 1981).
bPermeability ratio of Na+ versus Cl−. PNa/PCl in free solute is 0.66. Paracellular pathways with ratios above this value are more permeable for Na+ than Cl−, i.e., cation-selective.
cValues for cell lines are the personal observations of Dr. C. Van Itallie. Modified, with permission, from Van Itallie and Anderson (2004) (© American Thoracic Society).