PMID: 9164702Mar 1, 1997Paper

Effect of melittin on the apical membrane Na+ and Cl- conductances of frog cornea epithelium

Canadian Journal of Physiology and Pharmacology
G CarrasquerM A Dinno

Abstract

The transepithelial conductance increased with 10(-6) M melittin on the tear side of the frog cornea. This effect was attributed to the opening of an apical membrane Na+ conductance. However, the potency of the venom at this concentration (apical membrane fractional resistance (fRo) decreased to near zero) masked this and other effects. With 3 x 10(-7) M on the tear side, the effects were finite (fRo > 0) and reversible. With fRo > 0, the effects of melittin could be readily studied on the transport parameters of Na+, Cl-, and K+. Epithelial cells of intact bullfrog corneas were impaled with microelectrodes using an in vitro preparation. Under short-circuit current (Isc) conditions, 20 min after melittin Isc increased by 3.1 from 8.2 microA/cm2., fRo decreased by 18 from 51%; the intracellular potential, Vo, depolarized by 19.4 from -56.5 mV; and the transepithelial conductance, gv increased by 0.57 from 0.29 mS/cm2. Tenfold decreases in tear Na+ or Cl- concentrations changed the transport parameters consistent with the formation of a Na+ conductance and an increase in the apical membrane Cl- conductance by the venom. These conclusions were further supported by the minimal effect of melittin in Cl(-)-fre and, particularly, in N...Continue Reading

References

Sep 30, 1976·Pflügers Archiv : European journal of physiology·W Nagel
Nov 30, 1992·Annals of the New York Academy of Sciences·J CuppolettiD H Malinowska
Dec 1, 1990·Archives of Biochemistry and Biophysics·J Cuppoletti, A J Abbott
Nov 15, 1989·Archives of Biochemistry and Biophysics·J CuppolettiD H Malinowska
Oct 1, 1981·Biophysical Journal·M T Tosteson, D C Tosteson
Feb 1, 1996·Proceedings of the Society for Experimental Biology and Medicine·G CarrasquerM A Dinno

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