K+ reabsorption by the lower Malpighian tubule of Rhodnius prolixus: Inhibition by Ba2+ and blockers of H+/K+-ATPases

Active K⁺ reabsorption by the lower Malpighian tubule of the blood- feeding hemipteran Rhodnius prolixus does not involve the amiloride-sensitive K⁺/H⁺ exchangers or V-type H⁺-ATPases implicated in secretion of ions from haemolymph to lumen in the upper tubule. Amiloride, N-ethylmaleimide, 4- chloro-7-nitrobenzo-2-oxa- 1,3-diazol and bafilomycin A1 inhibit haemolymph- to-lumen secretion of Na⁺ and K⁺ by the upper Malpighian tubule, but have …