Sensitivity of valinomycin-based K(+)-selective micro-electrodes to inhibitors of K+ transport.
The sensitivies of double-barrelled K(+)-selective micro-electrodes (KSMs) employing the low-impedance membrane cocktail based on the neutral K(+)-selective ion carrier valinomycin (Fluka, Cocktail B 60398) to the following 3 different classes of inhibitors of K+ transport were measured: (1) general metabolic inhibitors (dinitrophenol, potassium cyanide, sodium azide, rotenone, dicyclohexylcarbodiimide, salicylhydroxamic acid); (2) P-type ATPase inhibitors (vanadate, ouabain, amiloride, SCH 28080); and (3) anion-dependent K+ transport inhibitors (bumetanide, 4-acetamide-4-isothiocyanostilbene-2,2-disulphonic acid). Of the 12 inhibitors tested, only dinitrophenol had any significant effect on the response of KSMs to K+ activity. Comparison of the calibrations in solutions with and without 0.1 mM dinitrophenol showed that this inhibitor behaved as a 'classical' interferent whereby its contribution to the K+ activity signal was statistically significant at K+ activities of 36.0 mM and less. However, at higher K+ activities (97.0 mM), dinitrophenol interference was not significant. It was possible to correct for the DNP interference and to obtain measurements of intracellular K+ activity in insect muscles.
Department of Biology, Imperial College of Science, Technology and Medicine, London, UK.
E M
EM
Fitzgerald
M B
MB
Djamgoz
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D000838:Anions / Q000378:metabolism; D000963:Antimetabolites / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002138:Calibration; D004140:Dinitrophenols / Q000494:pharmacology; D066298:In Vitro Techniques; D007313:Insecta / Q000378:metabolism; D008839:Microelectrodes; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000032:analysis* / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology; D014634:Valinomycin / Q000737:chemistry*
D000838:Anions; D000963:Antimetabolites; D004140:Dinitrophenols; D014475:Uncoupling Agents; D014634:Valinomycin; D000251:Adenosine Triphosphatases; D011188:Potassium