Potassium conductance and internal calcium accumulation in a molluscan neurone
1. The Aplysia neurone R-15 was injected with the Ca 2+ sensitive dye arsenazo III. Changes in dye absorbance were measured with a differential spectrophotometer to monitor changes in the free internal Ca 2+ concentration, [Ca] i , during membrane depolarization and during intracellular Ca 2+ ion in...
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| Veröffentlicht in: | The Journal of physiology 1980-11, Vol.308 (1), p.287-313 |
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| description | 1. The Aplysia neurone R-15 was injected with the Ca 2+ sensitive dye arsenazo III. Changes in dye absorbance were measured with a differential spectrophotometer to monitor changes
in the free internal Ca 2+ concentration, [Ca] i , during membrane depolarization and during intracellular Ca 2+ ion injection under voltage clamp conditions.
2. The absorbance change, and thus [Ca] i , increases linearly with Ca 2+ injection intensity at constant duration. The absorbance change produced by a constant intensity Ca 2+ injection also increases with injection duration, but this increase is asymptotic.
3. The Ca 2+ activated K + current, I K, Ca , increases linearly with the increase in [Ca] i and its rise and decay follows closely the time course of the absorbance change produced by internal Ca 2+ injection.
4. The Ca 2+ activated K + conductance increases exponentially with membrane depolarization. The increase in K + conductance activated by a constant intensity and duration Ca 2+ injection is on average e-fold for a 25.3 mV change in membrane potential.
5. The difference in net outward K + current measured during depolarizing pulses to different membrane potentials in normal and in Ca 2+ free ASW was used as an index of I K, Ca . Its time course was approximately linear for the first 50-100 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 I K, Ca being brought about by the rise in [Ca] i during a pulse.
6. The relation between Ca 2+ activated K + conductance and membrane potential is bell shaped and resembles the absorbance vs . 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 G K, Ca .
7. The net outward K + current measured with depolarizing voltage pulses in normal and in Ca 2+ free ASW is increased when [Ca] i is elevated by internal Ca 2+ injection. With large and prolonged Ca 2+ injections the net outward current is depressed following the decline of [Ca] i .
8. The time and frequency dependent depression of the net outward K + current which occurs during repetitive stimulation is shown to have no obvious temporal relation to the increase in [Ca] i . The depression is relieved by an increase in [Ca] i caused by internal Ca 2+ injection.
9. The net outward K + current measured with brief |
| doi_str_mv | 10.1113/jphysiol.1980.sp013472 |
| format | Article |
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in the free internal Ca 2+ concentration, [Ca] i , during membrane depolarization and during intracellular Ca 2+ ion injection under voltage clamp conditions.
2. The absorbance change, and thus [Ca] i , increases linearly with Ca 2+ injection intensity at constant duration. The absorbance change produced by a constant intensity Ca 2+ injection also increases with injection duration, but this increase is asymptotic.
3. The Ca 2+ activated K + current, I K, Ca , increases linearly with the increase in [Ca] i and its rise and decay follows closely the time course of the absorbance change produced by internal Ca 2+ injection.
4. The Ca 2+ activated K + conductance increases exponentially with membrane depolarization. The increase in K + conductance activated by a constant intensity and duration Ca 2+ injection is on average e-fold for a 25.3 mV change in membrane potential.
5. The difference in net outward K + current measured during depolarizing pulses to different membrane potentials in normal and in Ca 2+ free ASW was used as an index of I K, Ca . Its time course was approximately linear for the first 50-100 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 I K, Ca being brought about by the rise in [Ca] i during a pulse.
6. The relation between Ca 2+ activated K + conductance and membrane potential is bell shaped and resembles the absorbance vs . 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 G K, Ca .
7. The net outward K + current measured with depolarizing voltage pulses in normal and in Ca 2+ free ASW is increased when [Ca] i is elevated by internal Ca 2+ injection. With large and prolonged Ca 2+ injections the net outward current is depressed following the decline of [Ca] i .
8. The time and frequency dependent depression of the net outward K + current which occurs during repetitive stimulation is shown to have no obvious temporal relation to the increase in [Ca] i . The depression is relieved by an increase in [Ca] i caused by internal Ca 2+ injection.
9. The net outward K + current measured with brief depolarizing pulses which approach the estimated Ca 2+ equilibrium potential and therefore do not cause Ca 2+ influx and accumulation is facilitated by a previous depolarizing pulse which causes a rise in [Ca] i ..
10. The facilitation experiments also suggest that the activation of I K, Ca by [Ca] i has a significant time constant. During a depolarizing pulse, the rise in [Ca] i next to the membrane, and hence I K, Ca is expected to follow the square root of time, but a delay in the activation of I K, Ca by [Ca] i could explain why the observed time course of I K, Ca is initially almost linear.
11. The potential dependence of the Ca 2+ activated K + conductance can be explained if the internal Ca 2+ binding site is about half way through the membrane.</description><identifier>ISSN: 0022-3751</identifier><identifier>EISSN: 1469-7793</identifier><identifier>DOI: 10.1113/jphysiol.1980.sp013472</identifier><identifier>PMID: 7230018</identifier><language>eng</language><publisher>England: The Physiological Society</publisher><subject>Animals ; Aplysia ; Aplysia - physiology ; Arsenazo III ; Calcium - metabolism ; Calcium - pharmacology ; Electric Conductivity ; In Vitro Techniques ; Kinetics ; Marine ; Membrane Potentials - drug effects ; Mollusca ; Neurons - metabolism ; Neurons - physiology ; Potassium - physiology ; Spectrophotometry</subject><ispartof>The Journal of physiology, 1980-11, Vol.308 (1), p.287-313</ispartof><rights>1980 The Physiological Society</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c4487-b7d92657383c3d06d284dee8c9b9573978c16351c232f8c1b1b2559a955a1e993</citedby></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1274549/pdf/$$EPDF$$P50$$Gpubmedcentral$$H</linktopdf><linktohtml>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1274549/$$EHTML$$P50$$Gpubmedcentral$$H</linktohtml><link.rule.ids>230,314,723,776,780,881,1411,27901,27902,45550,45551,53766,53768</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/7230018$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Gorman, A. L. F.</creatorcontrib><creatorcontrib>Thomas, M. V.</creatorcontrib><title>Potassium conductance and internal calcium accumulation in a molluscan neurone</title><title>The Journal of physiology</title><addtitle>J Physiol</addtitle><description>1. The Aplysia neurone R-15 was injected with the Ca 2+ sensitive dye arsenazo III. Changes in dye absorbance were measured with a differential spectrophotometer to monitor changes
in the free internal Ca 2+ concentration, [Ca] i , during membrane depolarization and during intracellular Ca 2+ ion injection under voltage clamp conditions.
2. The absorbance change, and thus [Ca] i , increases linearly with Ca 2+ injection intensity at constant duration. The absorbance change produced by a constant intensity Ca 2+ injection also increases with injection duration, but this increase is asymptotic.
3. The Ca 2+ activated K + current, I K, Ca , increases linearly with the increase in [Ca] i and its rise and decay follows closely the time course of the absorbance change produced by internal Ca 2+ injection.
4. The Ca 2+ activated K + conductance increases exponentially with membrane depolarization. The increase in K + conductance activated by a constant intensity and duration Ca 2+ injection is on average e-fold for a 25.3 mV change in membrane potential.
5. The difference in net outward K + current measured during depolarizing pulses to different membrane potentials in normal and in Ca 2+ free ASW was used as an index of I K, Ca . Its time course was approximately linear for the first 50-100 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 I K, Ca being brought about by the rise in [Ca] i during a pulse.
6. The relation between Ca 2+ activated K + conductance and membrane potential is bell shaped and resembles the absorbance vs . 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 G K, Ca .
7. The net outward K + current measured with depolarizing voltage pulses in normal and in Ca 2+ free ASW is increased when [Ca] i is elevated by internal Ca 2+ injection. With large and prolonged Ca 2+ injections the net outward current is depressed following the decline of [Ca] i .
8. The time and frequency dependent depression of the net outward K + current which occurs during repetitive stimulation is shown to have no obvious temporal relation to the increase in [Ca] i . The depression is relieved by an increase in [Ca] i caused by internal Ca 2+ injection.
9. The net outward K + current measured with brief depolarizing pulses which approach the estimated Ca 2+ equilibrium potential and therefore do not cause Ca 2+ influx and accumulation is facilitated by a previous depolarizing pulse which causes a rise in [Ca] i ..
10. The facilitation experiments also suggest that the activation of I K, Ca by [Ca] i has a significant time constant. During a depolarizing pulse, the rise in [Ca] i next to the membrane, and hence I K, Ca is expected to follow the square root of time, but a delay in the activation of I K, Ca by [Ca] i could explain why the observed time course of I K, Ca is initially almost linear.
11. The potential dependence of the Ca 2+ activated K + conductance can be explained if the internal Ca 2+ binding site is about half way through the membrane.</description><subject>Animals</subject><subject>Aplysia</subject><subject>Aplysia - physiology</subject><subject>Arsenazo III</subject><subject>Calcium - metabolism</subject><subject>Calcium - pharmacology</subject><subject>Electric Conductivity</subject><subject>In Vitro Techniques</subject><subject>Kinetics</subject><subject>Marine</subject><subject>Membrane Potentials - drug effects</subject><subject>Mollusca</subject><subject>Neurons - metabolism</subject><subject>Neurons - physiology</subject><subject>Potassium - physiology</subject><subject>Spectrophotometry</subject><issn>0022-3751</issn><issn>1469-7793</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1980</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNqNkU1vFCEch4mxqWv1I2jmpF5my-sAFxNttLVpag_1TBiG7dIwsMJgs99eJrNt9GI88fJ7_k8gPwDeIrhGCJHT-912n130ayQFXOcdRIRy_AysEO1ky7kkz8EKQoxbwhl6AV7mfA8rBKU8Bscck3oQK3B9EyedsytjY2IYipl0MLbRYWhcmGwK2jdGezMD2pgyFq8nF0NNG92M0fuSjQ5NsCXFYF-Bo4322b4-rCfgx9cvt2cX7dX3829nn65aQ6ngbc8HiTvGiSCGDLAbsKCDtcLIXtZbyYVBHWHIYII3dd-jHjMmtWRMIyslOQEfF--u9KMdjA1T0l7tkht12quonfo7CW6r7uIvhTCnjM6CdwdBij-LzZMaXTbWex1sLFnxCjFMaAU__BNEXSdwVdKuot2CmhRzTnbz9B4E1VyaeixNzaWpx9Lq4Js_f_M0dmip5p-X_MF5u_9Pq7q9vJkvCBQIC14l7xfJ1t1tH1yyahnL0Tg77VXlFFIz-Ru2Lrmz</recordid><startdate>19801101</startdate><enddate>19801101</enddate><creator>Gorman, A. L. F.</creator><creator>Thomas, M. V.</creator><general>The Physiological Society</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7QP</scope><scope>7TK</scope><scope>F1W</scope><scope>H95</scope><scope>L.G</scope><scope>7X8</scope><scope>5PM</scope></search><sort><creationdate>19801101</creationdate><title>Potassium conductance and internal calcium accumulation in a molluscan neurone</title><author>Gorman, A. L. F. ; Thomas, M. V.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c4487-b7d92657383c3d06d284dee8c9b9573978c16351c232f8c1b1b2559a955a1e993</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1980</creationdate><topic>Animals</topic><topic>Aplysia</topic><topic>Aplysia - physiology</topic><topic>Arsenazo III</topic><topic>Calcium - metabolism</topic><topic>Calcium - pharmacology</topic><topic>Electric Conductivity</topic><topic>In Vitro Techniques</topic><topic>Kinetics</topic><topic>Marine</topic><topic>Membrane Potentials - drug effects</topic><topic>Mollusca</topic><topic>Neurons - metabolism</topic><topic>Neurons - physiology</topic><topic>Potassium - physiology</topic><topic>Spectrophotometry</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Gorman, A. L. F.</creatorcontrib><creatorcontrib>Thomas, M. V.</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>Calcium & Calcified Tissue Abstracts</collection><collection>Neurosciences Abstracts</collection><collection>ASFA: Aquatic Sciences and Fisheries Abstracts</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) 1: Biological Sciences & Living Resources</collection><collection>Aquatic Science & Fisheries Abstracts (ASFA) Professional</collection><collection>MEDLINE - Academic</collection><collection>PubMed Central (Full Participant titles)</collection><jtitle>The Journal of physiology</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Gorman, A. L. F.</au><au>Thomas, M. V.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Potassium conductance and internal calcium accumulation in a molluscan neurone</atitle><jtitle>The Journal of physiology</jtitle><addtitle>J Physiol</addtitle><date>1980-11-01</date><risdate>1980</risdate><volume>308</volume><issue>1</issue><spage>287</spage><epage>313</epage><pages>287-313</pages><issn>0022-3751</issn><eissn>1469-7793</eissn><abstract>1. The Aplysia neurone R-15 was injected with the Ca 2+ sensitive dye arsenazo III. Changes in dye absorbance were measured with a differential spectrophotometer to monitor changes
in the free internal Ca 2+ concentration, [Ca] i , during membrane depolarization and during intracellular Ca 2+ ion injection under voltage clamp conditions.
2. The absorbance change, and thus [Ca] i , increases linearly with Ca 2+ injection intensity at constant duration. The absorbance change produced by a constant intensity Ca 2+ injection also increases with injection duration, but this increase is asymptotic.
3. The Ca 2+ activated K + current, I K, Ca , increases linearly with the increase in [Ca] i and its rise and decay follows closely the time course of the absorbance change produced by internal Ca 2+ injection.
4. The Ca 2+ activated K + conductance increases exponentially with membrane depolarization. The increase in K + conductance activated by a constant intensity and duration Ca 2+ injection is on average e-fold for a 25.3 mV change in membrane potential.
5. The difference in net outward K + current measured during depolarizing pulses to different membrane potentials in normal and in Ca 2+ free ASW was used as an index of I K, Ca . Its time course was approximately linear for the first 50-100 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 I K, Ca being brought about by the rise in [Ca] i during a pulse.
6. The relation between Ca 2+ activated K + conductance and membrane potential is bell shaped and resembles the absorbance vs . 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 G K, Ca .
7. The net outward K + current measured with depolarizing voltage pulses in normal and in Ca 2+ free ASW is increased when [Ca] i is elevated by internal Ca 2+ injection. With large and prolonged Ca 2+ injections the net outward current is depressed following the decline of [Ca] i .
8. The time and frequency dependent depression of the net outward K + current which occurs during repetitive stimulation is shown to have no obvious temporal relation to the increase in [Ca] i . The depression is relieved by an increase in [Ca] i caused by internal Ca 2+ injection.
9. The net outward K + current measured with brief depolarizing pulses which approach the estimated Ca 2+ equilibrium potential and therefore do not cause Ca 2+ influx and accumulation is facilitated by a previous depolarizing pulse which causes a rise in [Ca] i ..
10. The facilitation experiments also suggest that the activation of I K, Ca by [Ca] i has a significant time constant. During a depolarizing pulse, the rise in [Ca] i next to the membrane, and hence I K, Ca is expected to follow the square root of time, but a delay in the activation of I K, Ca by [Ca] i could explain why the observed time course of I K, Ca is initially almost linear.
11. The potential dependence of the Ca 2+ activated K + conductance can be explained if the internal Ca 2+ binding site is about half way through the membrane.</abstract><cop>England</cop><pub>The Physiological Society</pub><pmid>7230018</pmid><doi>10.1113/jphysiol.1980.sp013472</doi><tpages>27</tpages><oa>free_for_read</oa></addata></record> |
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| subjects | Animals Aplysia Aplysia - physiology Arsenazo III Calcium - metabolism Calcium - pharmacology Electric Conductivity In Vitro Techniques Kinetics Marine Membrane Potentials - drug effects Mollusca Neurons - metabolism Neurons - physiology Potassium - physiology Spectrophotometry |
| title | Potassium conductance and internal calcium accumulation in a molluscan neurone |
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