{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T23:24:19Z","timestamp":1771629859578,"version":"3.50.1"},"reference-count":0,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[1977,9,1]],"date-time":"1977-09-01T00:00:00Z","timestamp":241920000000},"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":[[1977,9]]},"abstract":"<jats:p>1. Ion\u2010sensitive electrodes (made with a chloride\u2010sensitive ion\u2010exchange resin) were used to measure the internal chloride activity (<jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub><jats:sup>Cl<\/jats:sup>) of frog sartorius fibres at 25\u00b0 C.<\/jats:p><jats:p>2. The internal pH (pH<jats:sub>i<\/jats:sub>) of other sartorius fibres was measured with a recessed tip pH\u2010sensitive electrode (made with pH\u2010sensitive glass).<\/jats:p><jats:p>3. In normal bicarbonate\u2010free solution (containing 2\u00b75 m\n<jats:sc>M<\/jats:sc> potassium), the average chloride equilibrium potential, <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> (calculated from <jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub><jats:sup>Cl<\/jats:sup> and the measured chloride activity of the external solution (<jats:italic>a<\/jats:italic><jats:sub>o<\/jats:sub><jats:sup>Cl<\/jats:sup>) was 87\u00b77 \u00b1 1\u00b77 mV (mean \u00b1 \n<jats:sc>S.E.<\/jats:sc>; <jats:italic>n<\/jats:italic> = 16) in fibres where the average membrane potential, <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub>, was 88\u00b73 \u00b1 1\u00b75 mV (mean \u00b1 \n<jats:sc>S.E.<\/jats:sc>; <jats:italic>n<\/jats:italic> = 16). In experiments where <jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub><jats:sup>Cl<\/jats:sup> was varied between about 1 and 10 m\n<jats:sc>M<\/jats:sc> (which corresponds to values of <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> between about \u2010105 and \u201050 mV) <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> was within 1\u20103 mV of <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> at equilibrium. These measurements of <jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub><jats:sup>Cl<\/jats:sup> were obtained from the potential difference between the chloride\u2010sensitive electrode and an intracellular indifferent micro\u2010electrode filled with potassium chloride. If a potassium sulphate\u2010filled indifferent micro\u2010electrode was used, then values of <jats:italic>a<\/jats:italic><jats:sub>i<\/jats:sub><jats:sup>Cl<\/jats:sup> below about 5 m\n<jats:sc>M<\/jats:sc> were erroneously high, probably due to interference from other sarcoplasmic ions at the indifferent electrode.<\/jats:p><jats:p>4. In solutions containing 15 m\n<jats:sc>M<\/jats:sc> bicarbonate and gassed with 5% CO<jats:sub>2<\/jats:sub>, pH<jats:sub>i<\/jats:sub> was 6\u00b79, corresponding to an internal bicarbonate concentration of 7\u00b76 m\n<jats:sc>M<\/jats:sc>. <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> measured in this solution was some 4 mV positive to <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub>. Most of the difference between <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> and <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> could be ascribed to interference by sarcoplasmic bicarbonate on the basis of selectivity measurements of chloride against bicarbonate made on the ion\u2010exchange resin in the relevant range of <jats:italic>a<\/jats:italic><jats:sup>Cl<\/jats:sup>.<\/jats:p><jats:p>5. If bicarbonate\/CO<jats:sub>2<\/jats:sub> in the external solution was replaced by \n<jats:sc>HEPES<\/jats:sc>\/pure O<jats:sub>2<\/jats:sub> at constant pH, then pH<jats:sub>i<\/jats:sub> rose from 6\u00b788 \u00b1 0\u00b702 (mean \u00b1 \n<jats:sc>S.E.<\/jats:sc>) to 7\u00b705 \u00b1 0\u00b702. A change in external pH of 1 unit caused pH<jats:sub>i<\/jats:sub> to change by about 0\u00b702 unit and the intracellular buffering power was calculated to be about 35.<\/jats:p><jats:p>6. In solution made hypertonic by the addition of sucrose, <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> changed little or depolarized and <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> and <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> remained close. In contrast, in solution made hypertonic by the addition of solid sodium chloride (high\u2010chloride solution) <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> became negative to <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub>. Conversely in low chloride solution <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> became positive to <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub>.<\/jats:p><jats:p>7. When the chloride permeability (<jats:italic>P<\/jats:italic><jats:sub>Cl<\/jats:sub>) was reduced by the use of acid solution, <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub> moved positive to <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> indicating an accumulation of internal chloride. When <jats:italic>P<\/jats:italic><jats:sub>Cl<\/jats:sub> was increased again by returning to more alkaline solution, <jats:italic>E<\/jats:italic><jats:sub>m<\/jats:sub> depolarized to <jats:italic>E<\/jats:italic><jats:sub>Cl<\/jats:sub>.<\/jats:p><jats:p>8. The results are consistent with the existence of a small, active movement of chloride, the effects of which are normally obscured by large passive movements of chloride when <jats:italic>P<\/jats:italic><jats:sub>Cl<\/jats:sub> is large.<\/jats:p>","DOI":"10.1113\/jphysiol.1977.sp011983","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T08:18:52Z","timestamp":1418977132000},"page":"801-833","source":"Crossref","is-referenced-by-count":52,"title":["Continuous direct measurement of intracellular chloride and pH in frog skeletal muscle"],"prefix":"10.1113","volume":"270","author":[{"given":"T. B.","family":"Bolton","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R. D.","family":"Vaughan-Jones","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1977,9]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1977.sp011983","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1977.sp011983","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,5]],"date-time":"2023-11-05T15:28:05Z","timestamp":1699198085000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1977.sp011983"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1977,9]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1977,9]]}},"alternative-id":["10.1113\/jphysiol.1977.sp011983"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1977.sp011983","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1977,9]]}}}