title: Measurement of potassium and chloride ion concentrations in the cupulae of the lateral lines of Xenopus laevis.
abstract: 1. Potential measurements were made with double barrel ion selective electrodes from the cupulae of lateral line organs in the aquatic toad Xenopus laevis. 2. A positive endocupular potential (ECP) of 15-50 mV was recorded within the cupula, immediately above the hair cells. 3. Increases in the Cl- and K+ potentials were recorded when the ion selective electrodes touched the cupula. Cupular Cl- and K+ varied between 35 and 70 mM and 24 and 100 mM respectively. This variation existed between, rather than within, different animals. 4. Subcutaneous injections of 0-4 ml. 2 mM ouabain greatly reduced the ECP and cupular K+, whereas 0-4 ml. of Xenopus Ringer had no effect. 5. Changing the bath Cl- a hundredfold had no effect on the ECP. It was concluded that the ECP was produced by an electrogenic K+ pump which maintained high K+ levels within the cupula.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002712:Chlorides / Q000378:metabolism*; D004594:Electrophysiology; D005260:Female; D008297:Male; D008564:Membrane Potentials; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012679:Sense Organs / Q000187:drug effects / Q000378:metabolism*; D014981:Xenopus / Q000502:physiology*
chemical_list: D002712:Chlorides; D010042:Ouabain; D011188:Potassium