Abstract
Cl- transport was shown to be altered in skin fibroblasts from cystic fibrosis (CF) patients (Rugolo et al.,1986), and an abnormal Cl- metabolism was also observed by Mattes et al. (1987). In the present study we have investigated the effect of two cAMP analogs, 8-Bromo cyclic AMP (8-Br-cAMP) and dibutyryl cyclic AMP (dbt-cAMP), of a beta agonist, isoproterenol, on 36C1- efflux from normal and CF fibroblasts. Cl- efflux consists of a superposition of two efflux events, operationally defined as two compartments, each exhibiting first order exponential decay. In table 1 it is shown that 15 min preincubation in the presence of cAMP analogs (O.lmM 8-Br-cAMP and ImM dbt-cAMP) and isoproterenol (5µM) increased the rate constant (k) of Cl-efflux from the fast compartment of 10%, 5% and 9% respectively, in both normal and CF fibroblasts. These results are in disagreement with those previously reported by Lin and Gruenstein, 1987, who observed a 13% stimulation of Cl- efflux in normal fibroblasts, but failed to detect any activation in CF cells. However, in our experiments, the extent of activation of Cl- transport by the cAMP-dependent effectors was weak in control cells, so that no difference could be detected between normal and CF fibroblasts.
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References
Lin, P. and Gruenstein, E., 1987, Identification of a defective cAMP-stimulated Cl-channel in cystic fibrosis fibro blasts, J. Biol. Chem., 262:15345.
Mattes, P.M., Maloney, P.C. and Littlefield, J.W., 1987, Altered chloride metabolism in cultured cystic fibrosis skin fibroblasts, Proc. Natl. Acad. Sci. USA, 84:3009.
Rugolo, M., Romeo, G. and Lenaz, G., 1986, Kinetic analysis of chloride efflux from normal and cystic fibrosis fibroblasts, Biochem. Biophys. Res. Comm.,160:1330.
Rugolo, M., Mastrocola, T., Flamigni, A. and Lenaz, G., 1989, Chloride transport in human fibroblasts is activated by hypotonic shock, Biochem. Biophys. Res. Comm., 160:1330.
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© 1991 Springer Science+Business Media New York
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Mastrocola, T., Rugolo, M. (1991). The Response of Chloride Transport to Cyclic AMP, Calcium and Hypotonic Shock in Normal and Cystic Fibrosis Fibroblasts. In: Tsui, LC., Romeo, G., Greger, R., Gorini, S. (eds) The Identification of the CF (Cystic Fibrosis) Gene. Advances in Experimental Medicine and Biology, vol 290. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-5934-0_43
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DOI: https://doi.org/10.1007/978-1-4684-5934-0_43
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