Abstract
1. Calcium liberation induced in Xenopus oocytes by flash photorelease of inositol 1,4,5-trisphosphate (InsP3) from a caged precursor was monitored by confocal microfluorimetry. The object was to determine whether inhibition of Ca2+ release seen with paired flashes arose as a direct consequence of elevated cytosolic free [Ca2+]. 2. Responses evoked by just-suprathreshold test flashes were not inhibited by subthreshold conditioning flashes, but were strongly suppressed when conditioning flashes were raised above threshold. 3. Inhibition at first increased progressively as the inter-flash interval was lengthened to about 2 s and thereafter declined, with a half-recovery at about 4 s. 4. Intracellular injections of Ca2+ caused relatively slight inhibition of InsP3-evoked signals, even when cytosolic free [Ca2+] was elevated to levels similar to those at which strong inhibition was seen in paired-flash experiments. 5. Recovery from inhibition was not appreciably slowed when Ca2+ was injected to raise the free Ca2+ level between paired flashes. 6. We conclude that inhibition of InsP3-evoked Ca2+ liberation is not directly proportional to cytosolic free Ca2+ level and that recovery from inhibition in paired-pulse experiments involves factors other than the decline of cytosolic [Ca2+] following a conditioning response.
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Selected References
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- Berridge M. J. Inositol trisphosphate and calcium signalling. Nature. 1993 Jan 28;361(6410):315–325. doi: 10.1038/361315a0. [DOI] [PubMed] [Google Scholar]
- Berridge M. J. Inositol trisphosphate-induced membrane potential oscillations in Xenopus oocytes. J Physiol. 1988 Sep;403:589–599. doi: 10.1113/jphysiol.1988.sp017266. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bezprozvanny I., Watras J., Ehrlich B. E. Bell-shaped calcium-response curves of Ins(1,4,5)P3- and calcium-gated channels from endoplasmic reticulum of cerebellum. Nature. 1991 Jun 27;351(6329):751–754. doi: 10.1038/351751a0. [DOI] [PubMed] [Google Scholar]
- Camacho P., Lechleiter J. D. Increased frequency of calcium waves in Xenopus laevis oocytes that express a calcium-ATPase. Science. 1993 Apr 9;260(5105):226–229. doi: 10.1126/science.8385800. [DOI] [PubMed] [Google Scholar]
- Finch E. A., Turner T. J., Goldin S. M. Calcium as a coagonist of inositol 1,4,5-trisphosphate-induced calcium release. Science. 1991 Apr 19;252(5004):443–446. doi: 10.1126/science.2017683. [DOI] [PubMed] [Google Scholar]
- Levitan I., Hillman P., Payne R. Fast desensitization of the response to InsP3 in Limulus ventral photoreceptors. Biophys J. 1993 Apr;64(4):1354–1360. doi: 10.1016/S0006-3495(93)81470-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Levy S., Payne R. A lingering elevation of Cai accompanies inhibition of inositol 1,4,5 trisphosphate-induced Ca release in Limulus ventral photoreceptors. J Gen Physiol. 1993 Jan;101(1):67–84. doi: 10.1085/jgp.101.1.67. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Missiaen L., Taylor C. W., Berridge M. J. Luminal Ca2+ promoting spontaneous Ca2+ release from inositol trisphosphate-sensitive stores in rat hepatocytes. J Physiol. 1992 Sep;455:623–640. doi: 10.1113/jphysiol.1992.sp019319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ogden D. C., Capiod T., Walker J. W., Trentham D. R. Kinetics of the conductance evoked by noradrenaline, inositol trisphosphate or Ca2+ in guinea-pig isolated hepatocytes. J Physiol. 1990 Mar;422:585–602. doi: 10.1113/jphysiol.1990.sp018002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Parker I., Ivorra I. Characteristics of membrane currents evoked by photoreleased inositol trisphosphate in Xenopus oocytes. Am J Physiol. 1992 Jul;263(1 Pt 1):C154–C165. doi: 10.1152/ajpcell.1992.263.1.C154. [DOI] [PubMed] [Google Scholar]
- Parker I., Ivorra I. Confocal microfluorimetry of Ca2+ signals evoked in Xenopus oocytes by photoreleased inositol trisphosphate. J Physiol. 1993 Feb;461:133–165. doi: 10.1113/jphysiol.1993.sp019506. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Parker I., Ivorra I. Inhibition by Ca2+ of inositol trisphosphate-mediated Ca2+ liberation: a possible mechanism for oscillatory release of Ca2+. Proc Natl Acad Sci U S A. 1990 Jan;87(1):260–264. doi: 10.1073/pnas.87.1.260. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Payne R., Flores T. M., Fein A. Feedback inhibition by calcium limits the release of calcium by inositol trisphosphate in Limulus ventral photoreceptors. Neuron. 1990 Apr;4(4):547–555. doi: 10.1016/0896-6273(90)90112-s. [DOI] [PubMed] [Google Scholar]
- Payne R., Potter B. V. Injection of inositol trisphosphorothioate into Limulus ventral photoreceptors causes oscillations of free cytosolic calcium. J Gen Physiol. 1991 Jun;97(6):1165–1186. doi: 10.1085/jgp.97.6.1165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Payne R., Walz B., Levy S., Fein A. The localization of calcium release by inositol trisphosphate in Limulus photoreceptors and its control by negative feedback. Philos Trans R Soc Lond B Biol Sci. 1988 Jul 26;320(1199):359–379. doi: 10.1098/rstb.1988.0082. [DOI] [PubMed] [Google Scholar]
- Wakui M., Potter B. V., Petersen O. H. Pulsatile intracellular calcium release does not depend on fluctuations in inositol trisphosphate concentration. Nature. 1989 May 25;339(6222):317–320. doi: 10.1038/339317a0. [DOI] [PubMed] [Google Scholar]
- Yao Y., Parker I. Ca2+ influx modulation of temporal and spatial patterns of inositol trisphosphate-mediated Ca2+ liberation in Xenopus oocytes. J Physiol. 1994 Apr 1;476(1):17–28. [PMC free article] [PubMed] [Google Scholar]
- Yao Y., Parker I. Inositol trisphosphate-mediated Ca2+ influx into Xenopus oocytes triggers Ca2+ liberation from intracellular stores. J Physiol. 1993 Aug;468:275–295. doi: 10.1113/jphysiol.1993.sp019771. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yao Y., Parker I. Potentiation of inositol trisphosphate-induced Ca2+ mobilization in Xenopus oocytes by cytosolic Ca2+. J Physiol. 1992 Dec;458:319–338. doi: 10.1113/jphysiol.1992.sp019420. [DOI] [PMC free article] [PubMed] [Google Scholar]
