Temperature-dependent changes in fluid transport across goldfish gallbladder

Abstract

Summary. The temperature dependence of fluid transport across in vitro preparations of goldfish gallbladder was measured using a gravimetric technique. Fluid transport showed a direct dependence on incubation temperature when the adaptation temperature was kept constant. For constant incubation temperature, transport fell as the adaptation temperature rose. The width of intercellular channels varied with incubation and adaptation temperature as expected if fluid were to cross the tissue by this route. The structure of the gallbladder was otherwise unaffected by changes of temperature. Intracellular concentrations of Na, K and C1 also depended on the environmental temperature of the fish. The levels of Na and C1 increased and the level of K decreased, at constant incubation temperature, as the adaptation temperature rose from 8 to 30 ~ These changes took two to three weeks to become apparent while fluid transport regulated within 20 hours of raising the environmental temperature. The osmotic permeability of the gallbladder remained independent of both incubation and adaptation temperature.The outcome of adaptation was to maintain constant both the ionic composition of the epithelium and the rate at which it could transport fluid, when these parameters were measured at incubation temperatures equal to the previous environmental temperature of the fish. The significance of these findings is discussed and a mechanism for regulation postulated which involves an initial regulation of salt entry into the rnucosa followed by long term changes in the pumping ability of newly synthesized cells.The mechanism whereby water is removed from bile held within the gallbladder is now understood in some detail, thanks largely to the work of Diamond and his co-workers (see the review of Diamond, 1968). The active extrusion of salt into intercellular channels creates a standing osmotic gradient which then provides the driving force for fluid movement

Intracellular gradients of ion activities in the epithelial cells of theNecturus gallbladder recorded with ion-selective microelectrodes

“…In fish 85 mM was reported by Diamond (1962b) and 65 mM by Cremaschi, Smith and Wooding (1973). In rabbit 65 mM was reported by Cremaschi, Henin and Ferroni (1974) and 90ram by Frizzel, Dugas and Schultz (1975).…”

Electrical parameters in gallbladders of different species their contribution to the origin of the transmural potential difference

“…[24] for rabbit and in ref. [6] for goldfish (many projections are present in rabbit, very few in goldfish). In the micrographs presented here toad lateral spaces appear especially noticeable, owing to the enormous development of the projections; this is quite similar to that reported in ref.…”

“…[1] for bullfrog, refs. [6,8] for fishes). Differences in conformations of intercellular channels, especially due to the number and structure of the projections from the cell lateral membranes, can be observed from the micrographs reported in ref.…”

Does amphotericin B unmask an electrogenic Na+ pump in rabbit gallbladder? shift of gallbladders with negative to gallbladders with positive transepithelial p.d.'s

“…Co., Model 3315). Samples assayed for Na +, K + and C1 were deproteinized in advance with 1:1 (vol/vol) 0.6M perchloric acid; Na + and K + were assayed by a flame spectrophotometer (Beckman DU 2); Ct-was titrated using a modified diphenilcarbazone method [8]. For further details about extracellular space determination with 3H-sucrose and about the calculations of cell ion concentrations see also references [3, 4, and 8].…”