Abstract
Electro-osmotic flow and streaming potential were demonstrated in frog skin and gastric mucosa by the oscillating method (Imai, et al 1986) in a Ussing chamber1, 2) . Electro-osmotic flow was monitored directly using a photodiode. The flow increased in proportion to the amplitude of the applied rectangular electropotential wave. Their ratios were 0.31μl/min/V /cm2 for the skin and 0.69, μl/min/V/cm2 for the gastric mucosa. In pH 7.4 Ringer solution, skin behaved as a cation exchanger and gastric mucosa as an anion exchanger. The electro-osmotic flow evoked by the potential oscillation was also measured against a constant osmotic flow induced by a sucrose gradient. The electric potential which balanced the finite osmotic flow was-241 mV /200 mOsm for the skin and 156 mV /100 mOsm for the gastric mucosa. The parameters of the theoretical model were also determined using the network thermodynamics. The values of the reflection coefficients (σCl-σNa) and hydraulic conductivities (Lp) were 0.14, 2 × 10-7 cm/sec/atm for the skin, and-0. 11, 4.5 × 10-7 cm/sec/atm for the gastric mucosa. The absolute values of reflection coefficients of each ion for the skin were σCl= 0.96 and σNa = 0.82.
