The effect of amiloride and benzimidazoleguanidine added to the inside medium on electrolyte pathways in the frog skin glands.

Serosal amiloride inhibits Na+, K+ and Cl- efflux and reduces short-circuit current and transepithelial conductance in noradrenaline-stimulated frog skin in which the sodium channels in the apical membrane are blocked by amiloride. BIG (benzimidazoleguanidine) inhibits Na+ and K+ efflux and reduces the short-circuit current. In some skins BIG decreased and in others it increased Cl- efflux and conductance. The variable response appears to be due not only to inhibition of salt extrusion from the gland cells but also to activation of Cl- transport through the mitochondria-rich cells, since it was shown that BIG could increase Cl- efflux in gland-free preparations. Different target mechanisms in the gland cells where the two substances may exert their effect are discussed.