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DRUG EFFECTS ON THE HYDRAULIC CONDUCTIVITY OF THE ISOLATED RABBIT CILIARY EPITHELIUM
Author(s) -
Green Keith,
Mayberry Linda
Publication year - 1985
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1985.sp002908
Subject(s) - in vivo , chemistry , hydraulic conductivity , amiloride , ciliary processes , biophysics , endocrinology , furosemide , medicine , pharmacology , intraocular pressure , biology , sodium , surgery , ecology , microbiology and biotechnology , organic chemistry , soil water
Three aspects of hydrostatically driven volume flow across the isolated rabbit ciliary epithelium have been examined. (1) Hydraulic conductivity was increased in a dose‐dependent manner by amiloride, but not by furosemide, indicating that amiloride may interfere with junctional permeability. The absence of a furosemide effect suggests that regulation of passive fluid movement may be independent of net ionic fluxes of either chloride or bicarbonate. Ethacrynic acid had no effect on hydraulic conductivity at concentrations below 10 −2 M. At 10 −2 M, hydraulic conductivity was decreased, suggesting that fluid pathways may be linked to ionic pathways. (2) Successive in vivo daily treatments with adrenergic agonists result in changes in the intraocular pressure response. Dose‐effect curves to in vitro agonists from eyes pre‐treated on successive days indicate that isoprenaline caused a lack of response in hydraulic conductivity after 3 d of in vivo treatment, adrenaline caused responses after 2 d which were about half of those found on day 0, while phenylephrine and noradrenaline had no influence on hydraulic conductivity. These data suggest that ,8‐agonists cause a deactivation or desensitization of some moiety which is coupled with regulation of hydraulic conductivity in a manner similar to that seen for the β‐receptor‐coupled adenylate cyclase. (3) While cyclic GMP was without effect, various modifiers of cyclic GMP activity increased hydraulic conductivity. Alteration of cellular cyclic GMP levels appears to exert some regulation over ciliary epithelial permeability.