{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T17:39:00Z","timestamp":1790185140998,"version":"4.1.0"},"reference-count":71,"publisher":"American Physiological Society","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Neurophysiology"],"published-print":{"date-parts":[[2003,7]]},"abstract":"<jats:p> Synaptic transmission at the photoreceptor synapse is characterized by continuous release of glutamate in darkness. Release is regulated by the intracellular calcium concentration ([Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup>]<jats:sub>i<\/jats:sub>). We here examined the physiological properties of exocytosis in tiger salamander ( Ambystoma tigrinum) retinal rods and cones. Patch-clamp capacitance measurements were used to monitor exocytosis elicited by a rapid and uniform increase in [Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup>]<jats:sub>i<\/jats:sub> by photolysis of the caged Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup> compound NP-EGTA. The amplitude of flash-induced increases in membrane capacitance (C<jats:sub>m<\/jats:sub>) varied monotonically with [Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup>]<jats:sub>i<\/jats:sub> beyond approximately 15 \u03bcM. The following two types of kinetic responses in C<jats:sub>m<\/jats:sub> were recorded in both rods and cones: 1) a single exponential rise (39% of cells) or 2) a double-exponential rise (61%). Average rate constants of rapid and slow exocytotic responses were 420 \u00b1 168 and 7.85 \u00b1 5.02 s<jats:sup>\u2013<\/jats:sup><jats:sup>1<\/jats:sup>, respectively. The rate constant for the single exponential exocytotic response was 17.5 \u00b1 12.4 s<jats:sup>\u2013<\/jats:sup><jats:sup>1<\/jats:sup>, not significantly different from that of the slow exocytotic response. Beyond the threshold [Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup>]<jats:sub>i<\/jats:sub> of approximately 15 \u03bcM, the average amplitude of rapid, slow, and single C<jats:sub>m<\/jats:sub> response were 0.84 \u00b1 0.35, 0.82 \u00b1 0.20, and 0.70 \u00b1 0.23 pF, respectively. Antibodies against synaptotagmin I, a vesicle protein associated with fast exocytosis, strongly stained the synaptic terminal of isolated photoreceptors, suggesting the presence of fusion-competent vesicles. Our results confirm that photoreceptors possess a large rapidly releasable pool activated by a low-affinity Ca<jats:sup>2<\/jats:sup><jats:sup>+<\/jats:sup> sensor whose kinetic and calcium-dependent properties are similar to those reported in retinal bipolar cells and cochlear hair cells. <\/jats:p>","DOI":"10.1152\/jn.01025.2002","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T06:01:10Z","timestamp":1149055270000},"page":"218-225","source":"Crossref","is-referenced-by-count":50,"title":["Properties of Exocytotic Response in Vertebrate Photoreceptors"],"prefix":"10.1152","volume":"90","author":[{"given":"M.","family":"Kreft","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D.","family":"Kri\u017eaj","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S.","family":"Grilc","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R.","family":"Zorec","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"REF1","doi-asserted-by":"publisher","DOI":"10.1016\/S0896-6273(01)00243-4"},{"key":"REF2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00374568"},{"key":"REF3","doi-asserted-by":"publisher","DOI":"10.1016\/S0006-3495(84)84244-7"},{"key":"REF4","doi-asserted-by":"publisher","DOI":"10.1016\/S0896-6273(00)80850-8"},{"key":"REF5","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.91.1.187"},{"key":"REF6","doi-asserted-by":"publisher","DOI":"10.1038\/35065004"},{"key":"REF7","doi-asserted-by":"publisher","DOI":"10.1038\/369493a0"},{"key":"REF8","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.91.26.12942"},{"key":"REF9","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.19-15-06309.1999"},{"key":"REF10","doi-asserted-by":"publisher","DOI":"10.1016\/0006-8993(71)90591-9"},{"key":"REF11","doi-asserted-by":"publisher","DOI":"10.1085\/jgp.111.2.225"},{"key":"REF12","doi-asserted-by":"publisher","DOI":"10.1038\/371513a0"},{"key":"REF13","doi-asserted-by":"publisher","DOI":"10.1016\/S0166-2236(96)10028-X"},{"key":"REF14","doi-asserted-by":"publisher","DOI":"10.1016\/S0166-2236(98)01293-4"},{"key":"REF15","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1996.sp021475"},{"key":"REF16","doi-asserted-by":"publisher","DOI":"10.1007\/s004240050387"},{"key":"REF17","doi-asserted-by":"publisher","DOI":"10.1152\/ajpcell.00333.2002"},{"key":"REF18","doi-asserted-by":"publisher","DOI":"10.2741\/A896"},{"key":"REF19","doi-asserted-by":"publisher","DOI":"10.1016\/S0896-6273(00)80531-0"},{"key":"REF20","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.19-17-07249.1999"},{"key":"REF21","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.2002.035683"},{"key":"REF22","doi-asserted-by":"publisher","DOI":"10.1016\/S0896-6273(00)80226-3"},{"key":"REF23","doi-asserted-by":"publisher","DOI":"10.1098\/rstb.1973.0033"},{"key":"REF24","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.19-01-00119.1999"},{"key":"REF25","doi-asserted-by":"publisher","DOI":"10.1002\/bies.1118"},{"key":"REF26","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.89.8.3625"},{"key":"REF27","doi-asserted-by":"publisher","DOI":"10.1017\/S0033583500003279"},{"key":"REF28","doi-asserted-by":"publisher","DOI":"10.1007\/BF00582306"},{"key":"REF29","doi-asserted-by":"publisher","DOI":"10.1016\/0896-6273(88)90181-X"},{"key":"REF30","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.80.22.7014"},{"key":"REF31","doi-asserted-by":"publisher","DOI":"10.1016\/S0896-6273(00)80254-8"},{"key":"REF32","unstructured":"Morgans CW.  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