BAY K 8644-induced oscillations in rabbit gall-bladder transepithelial potential difference
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The effects of the Ca2+-channel activator BAY K 8644 (a novel dihydropyridine) on transepithelial potential difference (Pd), electrical resistance (Rt), and unidirectional Na+-fluxes were studied in the rabbit gall-bladder.
It was observed that BAY K 8644 at concentrations between 10−7 and 10−5 M induced regular oscillations in the transepithelial Pd, without affecting the mean value of Pd (or Rt). The mean oscillatory frequency was 18 mHz (∼1 cycle per min), and the mean amplitude was 30–35 μV. Oscillations were predominantly elicited from the serosal side. 10−5 M BAY K 8644 reduced net Na+-absorption by 16% by inhibiting the mucosa-to-serosa flux. Nifedipine blocked the Pd-oscillations but did not reverse the Na+-transport inhibition.
The observed effects of BAY K 8644 are consistent with activation of Ca2+-channels and an increase in intracellular Ca2+-concentration.
Key wordsPd-oscillations Sodium transport BAY K 8644 Calcium Gall-bladder
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- 1.Berridge MJ, Lindley BD, Prince WT (1974) Role of calcium and cyclic AMP in controlling fly salivary gland secretion. In: Thorn NA, Petersen OH (eds) Secretory mechanisms of exocrine glands. Munksgaard, Copenhagen, pp 331–343Google Scholar
- 2.berridge MJ, Rapp PE (1979) A comparative survey of the function, mechanism and control of cellular oscillators. J Exp Biol 81:217–279Google Scholar
- 3.Frederiksen O, Leyssac PP (1977) Effects of cytochalasin B and dimethylsulphoxide on isosmotic fluid transport by rabbit gall-bladder in vitro. J Physiol (Lond) 265:103–118Google Scholar
- 4.Frederiksen O, Leyssac PP (1984) Possible role of calcium in the control of gall-bladder fluid absorption. In: Case RM, Lindgard JM, Young JA (eds) Secretion: mechanisms and control. University Press, Manchester, pp 207–211Google Scholar
- 5.Frömter E (1972) The route of passive ion movement through the epithelium ofNecturus gall-bladder. J Membr Biol 8: 259–301Google Scholar
- 6.Henin S, Cremaschi D (1975) Transcellular ion route in rabbit gall-bladder. Electric properties of the epithelial cells. Pflügers Arch 355:125–139Google Scholar
- 7.Hess P, Lansman JB, Tsien RW (1984) Different modes of Ca channel gating behaviour favoured by dihydropyridine Ca agonist and antagonist. Nature 311:538–544Google Scholar
- 8.Ishii K, Taira N, Yanagisawa T (1985) Differential antagonism by BAY K 8644, a dihydropyridine calcium agonist, of the negative inotropic effects of nifedipine, verapamil, diltiazem and manganese ions in canine ventricular muscle. Br J Pharmacol 84:577–584Google Scholar
- 9.Kennedy RH, Seifen E (1985) Stimulation frequency alters the inotropic response of atrial muscle to BAY K 8644. Eur J Pharmacol 107:209–214Google Scholar
- 10.Kinne-Saffran E, Kinne RT (1974) Localization of a calcium-stimulated ATPase in the basal-lateral plasma membranes of the proximal tubule of rat kidney cortex. J Membr Biol 17:263–274Google Scholar
- 11.Lassalles J-P, Hartmann A, Thellier M (1980) Oscillations of the electric potential of frog skin under the effect of Li+: experimental approach. J Membr Biol 56:107–119Google Scholar
- 12.Petersen OH, Maruyama Y (1984) Calcium-activated potassium channels and their role in secretion. Nature 307:693–696Google Scholar
- 13.Rapp PE (1979) An atlas of cellular oscillators. J Exp Biol 81:281–306Google Scholar
- 14.Rasmussen H, Barrett PQ (1984) Calcium messenger system: an integrated view. Physiol Rev 64:938–984Google Scholar
- 15.Scharff O, Foder B (1982) Rate constants for calmodulin binding to Ca2+-ATPase in erythrocytes. Biochim Biophys Acta 691:133–143Google Scholar
- 16.Scharff O, Foder B, Skibsted U (1983) Hysteretic activation of the Ca2+ pump revealed by calcium transients in human red cells. Biochim Biophys Acta 730:295–305Google Scholar
- 17.Schramm M, Thomas G, Towart R, Franckowiak G (1983) Novel dihydropyridine with positive inotropic action through activation of Ca2+-channels. Nature 303:535–537Google Scholar
- 18.Thomas G, Chung M, Cohen CJ (1985) A dihydropyridine (BAY K 8644) that enhances calcium currents in guinea pig and calf myocardial cells. Circ Res 56:87–96Google Scholar
- 19.Van Os CH, Ghijsen WEJM, De Jonge H (1981) High affinity Ca-ATPase in basolateral plasma membrane of rat duodenum and kidney cortex. In: Bronner F, Peterlik M (eds). Calcium and phosphate transport across biomembranes. Academic Press, New York, p 159Google Scholar
- 20.Vestergaard-Bogind B, Bennekou P (1982) Calcium-induced oscillations in K+ conductance and membrane potential of human erythrocytes mediated by the ionophore A23187. Biochim Biophys Acta 688:37–44Google Scholar
- 21.Windhager EE, Taylor A (1983) Regulatory role of intracellular calcium ions in epithelial Na transport. Annu Rev Physiol 45:519–532Google Scholar
- 22.Winfree AT (1967) Biological rhythms and the behavior of populations of coupled oscillators. J Theoret Biol 16:15–42Google Scholar