{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T14:57:37Z","timestamp":1770994657098,"version":"3.50.1"},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1980,11,1]],"date-time":"1980-11-01T00:00:00Z","timestamp":341884800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[1980,11]]},"abstract":"<jats:p>1. The <jats:italic>Aplysia<\/jats:italic> neurone R\u201015 was injected with the Ca<jats:sup>2+<\/jats:sup> sensitive dye arsenazo III. Changes in dye absorbance were measured with a differential spectrophotometer to monitor changes in the free internal Ca<jats:sup>2+<\/jats:sup> concentration, [Ca]<jats:sub>i<\/jats:sub>, during membrane depolarization and during intracellular Ca<jats:sup>2+<\/jats:sup> ion injection under voltage clamp conditions.<\/jats:p><jats:p>2. The absorbance change, and thus [Ca]<jats:sub>i<\/jats:sub>, increases linearly with Ca<jats:sup>2+<\/jats:sup> injection intensity at constant duration. The absorbance change produced by a constant intensity Ca<jats:sup>2+<\/jats:sup> injection also increases with injection duration, but this increase is asymptotic.<\/jats:p><jats:p>3. The Ca<jats:sup>2+<\/jats:sup> activated K<jats:sup>+<\/jats:sup> current, <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub>, increases linearly with the increase in [Ca]<jats:sub>i<\/jats:sub> and its rise and decay follows closely the time course of the absorbance change produced by internal Ca<jats:sup>2+<\/jats:sup> injection.<\/jats:p><jats:p>4. The Ca<jats:sup>2+<\/jats:sup> activated K<jats:sup>+<\/jats:sup> conductance increases exponentially with membrane depolarization. The increase in K<jats:sup>+<\/jats:sup> conductance activated by a constant intensity and duration Ca<jats:sup>2+<\/jats:sup> injection is on average e\u2010fold for a 25.3 mV change in membrane potential.<\/jats:p><jats:p>5. The difference in net outward K<jats:sup>+<\/jats:sup> current measured during depolarizing pulses to different membrane potentials in normal and in Ca<jats:sup>2+<\/jats:sup> free ASW was used as an index of <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub>. Its time course was approximately linear for the first 50\u2010100 msec of depolarization, but for longer times the relation approached a maximum. Simultaneous measurements of the arsenazo III absorbance changes were broadly consistent with the activation of <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub> being brought about by the rise in [Ca]<jats:sub>i<\/jats:sub> during a pulse.<\/jats:p><jats:p>6. The relation between Ca<jats:sup>2+<\/jats:sup> activated K<jats:sup>+<\/jats:sup> conductance and membrane potential is bell shaped and resembles the absorbance <jats:italic>vs<\/jats:italic>. potential curve, but its maximum is displaced to more positive membrane potentials. The shift in the two curves on the voltage axis can be explained by the potential dependence of <jats:italic>G<\/jats:italic><jats:sub>K, Ca<\/jats:sub>.<\/jats:p><jats:p>7. The net outward K<jats:sup>+<\/jats:sup> current measured with depolarizing voltage pulses in normal and in Ca<jats:sup>2+<\/jats:sup> free ASW is increased when [Ca]<jats:sub>i<\/jats:sub> is elevated by internal Ca<jats:sup>2+<\/jats:sup> injection. With large and prolonged Ca<jats:sup>2+<\/jats:sup> injections the net outward current is depressed following the decline of [Ca]<jats:sub>i<\/jats:sub>.<\/jats:p><jats:p>8. The time and frequency dependent depression of the net outward K<jats:sup>+<\/jats:sup> current which occurs during repetitive stimulation is shown to have no obvious temporal relation to the increase in [Ca]<jats:sub>i<\/jats:sub>. The depression is relieved by an increase in [Ca]<jats:sub>i<\/jats:sub> caused by internal Ca<jats:sup>2+<\/jats:sup> injection.<\/jats:p><jats:p>9. The net outward K<jats:sup>+<\/jats:sup> current measured with brief depolarizing pulses which approach the estimated Ca<jats:sup>2+<\/jats:sup> equilibrium potential and therefore do not cause Ca<jats:sup>2+<\/jats:sup> influx and accumulation is facilitated by a previous depolarizing pulse which causes a rise in [Ca]<jats:sub>i<\/jats:sub>..<\/jats:p><jats:p>10. The facilitation experiments also suggest that the activation of <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub> by [Ca]<jats:sub>i<\/jats:sub> has a significant time constant. During a depolarizing pulse, the rise in [Ca]<jats:sub>i<\/jats:sub> next to the membrane, and hence <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub> is expected to follow the square root of time, but a delay in the activation of <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub> by [Ca]<jats:sub>i<\/jats:sub> could explain why the observed time course of <jats:italic>I<\/jats:italic><jats:sub>K, Ca<\/jats:sub> is initially almost linear.<\/jats:p><jats:p>11. The potential dependence of the Ca<jats:sup>2+<\/jats:sup> activated K<jats:sup>+<\/jats:sup> conductance can be explained if the internal Ca<jats:sup>2+<\/jats:sup> binding site is about half way through the membrane.<\/jats:p>","DOI":"10.1113\/jphysiol.1980.sp013472","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T07:18:42Z","timestamp":1418973522000},"page":"287-313","source":"Crossref","is-referenced-by-count":95,"title":["Potassium conductance and internal calcium accumulation in a molluscan neurone"],"prefix":"10.1113","volume":"308","author":[{"given":"A. L. F.","family":"Gorman","sequence":"first","affiliation":[]},{"given":"M. V.","family":"Thomas","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[1980,11]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1980.sp013472","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1980.sp013472","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,6]],"date-time":"2023-11-06T00:45:27Z","timestamp":1699231527000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1980.sp013472"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1980,11]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1980,11]]}},"alternative-id":["10.1113\/jphysiol.1980.sp013472"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1980.sp013472","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1980,11]]}}}