. Author manuscript; available in PMC: 2010 May 1.

Published in final edited form as: Pflugers Arch. 2008 Sep 16;458(1):77–88. doi: 10.1007/s00424-008-0589-z

Table 1.

Methods for the determination of paracellular permeability

Methods	advantages	disadvantages / difficulties
*Electrophysiological Methods*

Resistance / Conductance Mesurement	easy to determine	not ion-specific (always sum of cation and anion conductance)
		always sum of trans- and paracellular pathway

Two path impedance spectroscopy / Conductance scanning	allows discrimination between trans- and paracellular pathway	not ion-specific intricate technique

Diffusion Potential Measurement	determination of relative ion permeabilities (e.g. P_Na/P_Cl)	liquid junction potentials calculation of activity coefficients
	absolute permeabilities, if combined with R^t measurements	limited to electrically charged solutes

*Flux Measurements*

steady-state conditions	direct determination of absolute permeabilities, including permeabilites to uncharged solutes	requires radioactive / fluorescence labelling
		development or unstirred layers / transepithelial potentials

zero - trans conditions	direct determination of absolute permeabilities, including permeabilites to uncharged solutes	may affect tight junction integrity
		development or unstirred layers / transepithelial potentials