Regulation of paracellular Na+ and Cl(-) conductances by hydrostatic pressure.
The effect of hydrostatic pressure on the paracellular ion conductance (Gp) composed of the Na(+) conductance (G(Na)) and the Cl(-) conductance (G(Cl)) has been Investigated. Gp, G(Na) and G(Cl) were time-dependently increased after applying an osmotic gradient generated by NaCl with basolateral hypotonicity. Hydrostatic pressure (1-4cm H2O) applied from the basolateral side enhanced the osmotic gradient-induced increase in Gp, G(Na) and G(Cl) in a magnitude-dependent manner, while the hydrostatic pressure applied from the apical side diminished the osmotic gradient-induced increase in Gp, G(Na) and G(Cl). How the hydrostatic pressure influences Gp, G(Na) and G(Cl) under an isosmotic condition was also investigated. Gp, G(Na) and G(Cl) were stably constant under a condition with basolateral application of sucrose canceling the NaCl-generated osmotic gradient (an isotonic condition). Even under this stable condition, the basolaterally applied hydrostatic pressure drastically elevated Gp, G(Na) and G(Cl), while apically applied hydrostatic pressure had little effect on Gp, G(Na) or G(Cl). Taken together, these observations suggest that certain factors controlled by the basolateral osmolality and the basolaterally applied hydrostatic pressure mainly regulate the Gp, G(Na) and G(Cl).
Tokuda
Shinsaku
S
Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
Niisato
Naomi
N
Nagai
Toshiki
T
Taruno
Akiyuki
A
Nakajima
Ken-Ichi
K
Miyazaki
Hiroaki
H
Yamada
Toshiki
T
Hosogi
Shigekuni
S
Ohta
Mariko
M
Nishio
Kyosuke
K
Iwasaki
Yoshinobu
Y
Marunaka
Yoshinori
Y
D000818:Animals; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D006874:Hydrostatic Pressure; D009997:Osmotic Pressure / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism / Q000502:physiology*; D014982:Xenopus laevis
D002712:Chlorides; D012965:Sodium Chloride; D012964:Sodium