[Ultrastructural aspects of lanthanum penetration in guinea gallbladder in function of the absorption flow of water].
It is controversial whether water crosses the paracellular pathway in leaky epithelia (i.e. gall bladder). Therefore, this paper explores whether variations in the absorptive volume flux (Jv) are correlated with different degrees of penetration of the extracellular marker La3+ at two osmolalities namely 300 and 100 mOsm/kg, which allow to vary Jv. Guinea pig gall bladders were perfused in vitro with oxygenated fluids containing 1 and/or 10 mM La3+, at physiological pH and temperature. Tissue samples were then prepared for transmission electron microscopy. In the micrographs, penetration of La3+ beginning at the apical end of the space was measured along the intercellular space toward its basal end. Two parameters were measured, namely degree of penetration (in microns) and number of intercellular spaces penetrated by La3+. Jv is twice as large in hyposmotic condition than in the isosmotic preparations. Different degrees of inter(para)cellular La3+ penetration were observed which keep a direct relation with Jv. La3+ was not detected in the cytoplasm which showed good preservation, also at 100 mOsm/kg, this indicate adequate cell membrane integrity. These results show that La3+ penetration varies with Jv, indicating a paracellular water flow.
Vargas-Janzen
A
A
Escuela de Bioanálisis, Facultad de Medicina, Universidad Central de Venezuela, Caracas.
Verde-Martínez
C
C
Whittembury
G
G
D000042:Absorption; D000818:Animals; D004848:Epithelium / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005704:Gallbladder / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D006168:Guinea Pigs; D007811:Lanthanum / Q000493:pharmacokinetics*; D008297:Male; D008854:Microscopy, Electron; D009994:Osmolar Concentration; D014867:Water / Q000378:metabolism / Q000502:physiology
D014867:Water; D007811:Lanthanum
Aspectos ultraestructurales de la penetración de lantano en vesícula biliar de cobayo en función del flujo de absorción de agua.