title: Effect of ionic changes, amino acids, and metabolic inhibitors on hydraulic conductivity of the isolated rabbit iris-ciliary body.
abstract: The hydraulic conductivity (Lp) of the rabbit ciliary epithelium has been measured under various conditions. Of the ionic changes in the bathing medium imposed upon the tissue, replacement of sodium and either depletion of bicarbonate or deletion of potassium all caused an increase in Lp. Chloride replacement had no effect on Lp. The changes in Lp occur more slowly than the changes in electrical parameters caused by the same perturbations and indicate that ions and fluid move across this tissue by different routes. Of the 10 amino acids tested, only three increased Lp; 2 basic and 1 neutral amino acid. No correlation existed between posterior chamber: plasma ratios, or the nature of the amino acid (i.e., basic, neutral, or acidic) and the effect on Lp. Of the metabolic inhibitors, only iodoacetic acid induced an increase in Lp. The transport inhibitor, ouabain, at concentrations up to 10(-4) M for 4 hours was without effect. The effects of these agents on electrophysiological parameters, therefore, must be confined to net ionic pathways. Inulin and sucrose permeabilities were determined under either a zero or 10 mmHg hydrostatic pressure gradient using radioactive tracers. Application of a hydrostatic pressure gradient increased sucrose permeability by ten-fold but only increased inulin permeability by 20%. This data, together with control tissues run in parallel with many of the experimental tissues, indicates that the tissue is not highly leaky and does not change characteristics with time.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002924:Ciliary Body / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects*; D004848:Epithelium / Q000187:drug effects; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007473:Ion Channels / Q000187:drug effects*; D007498:Iris / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000187:drug effects*
chemical_list: D000596:Amino Acids; D001639:Bicarbonates; D007461:Iodoacetates; D007473:Ion Channels; D010042:Ouabain; D012964:Sodium; D011188:Potassium; D019807:Iodoacetic Acid