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The exquisite sensitivity of elasmobranch fishes to electric fields is thought to reside in electroreceptive organs called ampullae of Lorenzini. We measured the stimulus-response behavior of ampullary organs excised from skates. Under open-circuit conditions, the ampullary organ showed three distinct response states: spontaneous repetitive spikes, evoked(More)
Two ampullary epithelial properties necessary for electroreception were used to identify the types of ion channels and transporters found in apical and basal membranes of ampullary receptor cells of skates and to assess their individual role under voltage-clamp conditions. The two essential properties are (1) a steady-state negative conductance generated in(More)
A steady, spontaneous current oscillation (1 nA p-p) occurs in voltage-clamped, isolated ampullary organs (canal, ampulla, and nerve) from skates (Raja). Spectral analysis showed that energy in the oscillation was confined to a narrow band of frequencies (3 Hz) about a fundamental frequency (32 Hz at 20 degrees C) and in harmonics. The frequency of the(More)
Three new C-methylated flavones, named as 5, 5'-dihydroxy-7-acetoxy-6, 8, 3", 3"-tetramethylpyran (3', 4')flavone I , 5, 5'-dihydroxy-7(a-methyl)butyroxyl-6. 8, 3", 3"-tetramethlpyran (3', 4')flavone 2 and 5, 5'-d ihydroxy-6. 7methylenedioxy-8 , 3", 3"-trimethylpy rnn (3', 4') fla vone 3 have been isolated along with three known fl avones from Elsholtzia(More)
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