Effects of bicarbonate on fluid and electrolyte transport by the guinea pig gallbladder: A bicarbonate-chloride exchange

Abstract

Fluid transport and net fluxes of Na, K, Cl and HCO3 by guinea pig gallbladder were investigated in vitro. A perfused gallbladder preparation was devised to simultaneously study unidirectional fluxes of 22Na and 36Cl. The net Cl flux exceeded the net Na flux during fluid absorption in the presence of HCO3. This Cl excess was counterbalanced by a net HCO3 secretion: a HCO3-Cl exchange. PGE1 reversed the direction of fluid transport and abolished the net Cl flux. The magnitude of the HCO3 secretion remained unchanged, but shifted from a HCO3-Cl exchange to a net secretion of NaHCO3 and KHCO3. Furosemide inhibited both the HCO3-Cl exchange and HCO3 secretion after PGE1 without influencing fluid absorption. Ouabain inhibited the HCO3-Cl exchange as well as fluid absorption; only the effect on the HCO3 secretion was entirely reversible. Secreted HCO3 appeared not to be derived from metabolic sources since HCO3 secretion was abolished in a HCO3-free bathing medium. HCO3 secretion was also dependent on the Na concentration of the bathing fluid. Three lines of evidence are presented in favor of an active HCO3 secretion in guinea pig gallbladder. HCO3 is secreted against: (i) a chemical gradient, (ii) an electrical gradient and (iii) the direction of fluid movement under control conditions.

Studies on the relationship between rat renal medullary cell volume and external anion concentration in hyperosmolal media.

“…It is only comparatively recently, however, that this and related anion exchanges have been studied in detail, not only in red blood cells (Deuticke, 1972;Cousin & Motais, 1976;Lambert & Lowe, 1978;Cabantchik, Knauf & Rothstein, 1978; Wieth, 1979) but also in excitable tissues (Thomas, 1977;Vaughan-Jones, 1979) and a wide variety of transporting epithelia including the gastric mucosa (Sanders, O'Callaghan, Butler & Rehm, 1972), turtle urinary bladder (Leslie, Schwartz & Steinmetz, 1973), the collecting duct of the exocrine pancreas (Swanson & Solomon, 1975), colon (Frizzell, Koch & Schultz, 1976) and gall-bladder (Heintze, Petersen, Olles, Saverymuttu & Wood, 1979).…”

Bicarbonate effects, electromotive forces and potassium effluxes in rabbit and guinea‐pig gall‐bladder.

“…In the guinea-pig HC03-both enhances Na+ salt absorption and elicits a HC0 3-secretion (Heintze et al 1979). In spite of these two overlapping effects, K+ activity largely and significantly decreases (by 44 4 + 4-3 mm) and Na+ activity increases (by 330 + 42 mM), a result which suggests that HCO3-also increases Na+ entry at the apical membrane in this species, as in the rabbit.…”

“…and Petersen, Wood, Schulze & Heintze (1981) have clearly shown that the latter hypothesis is more likely and also extended their study to guinea-pig gall-bladder. Bicarbonate effects are more complex in this species, since an HCO3-secretion is also elicited in the presence of the anion (Herman, Wilson & Kazyak, 1958;Heintze, Petersen, Ollen, Saverymuttu & Wood, 1979). We have demonstrated recently that the apical membrane exhibits an anion conductance in the guinea-pig, but not in the rabbit (Cremaschi & Meyer, 1982), so that a relationship might exist between HCO3-secretion and such a conductance, following the current models on anion secretion (Frizzell, Field & Schultz, 1979).…”

“…As a Na+-K+-activated ATPase only exists at the basolateral barrier (Van Os & Slegers, 1971;Mills & Di Bona, 1978) and both the apical and basolateral barriers are conductive to K+ (Henin & Cremaschi, 1975;Van Os & Slegers, 1975;Reuss & Finn, 1975a, b), a K+ secretion should be present, although this has not been observed (Wheeler, 1963;Dietschy & Moore, 1964;Heintze et al 1979). A second purpose of this paper is then to calculate the K+ efflux from the cell.…”

Communications

“…The efflux of radiolabelled calcium was markedly enhanced by prelabelling in the presence of theophylline and excess K+, as compared to prelabelling in the presence of excess K+ alone. The movements of chloride and bicarbonate ions across a variety of tissues have been shown to be inhibited by SITS (4-acetamido-4-isothiocyanatostilbene 2,2-disulphonic acid; see Heintze, Olles, Petersen & Wood, 1978). Although SITS inhibits net fluid flux in the proximal convoluted tubule of rat kidney (Green & Greenwood, 1978), its effect on tubular anion fluxes has not been reported.…”