title: Simultaneous measurement of intracellular Ca2+ and asynchronous transmitter release from the same crayfish bouton.
abstract: 1. A technique has been developed to monitor neurotransmitter release simultaneously with intracellular Ca2+ concentration ([Ca2+]i) in single release boutons whose diameters range from 3 to 5 microns. 2. Using this technique, we have found a highly non-linear relationship between the rate of asynchronous release and [Ca2+]i. The Hill coefficient lies between 3 and 4. 3. The affinity (Kd) of the putative release-related Ca2+ receptor for asynchronous release was calculated to be in the range of 2-4 microM. 4. The same range of values of Hill coefficient and Kd were obtained when [Ca2+]i was elevated both by bath application of ionomycin and by repetitive stimulation at high frequency. 5. Our results show that the Ca2+ receptor(s) associated with asynchronous release exhibits high affinity for Ca2+.
authors.affiliation: Otto Loewi Centre for Cellular and Molecular Neurobiology, Department of Neurobiology, Hebrew University, Jerusalem, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Ravin
authors.forename: M E
authors.initials: ME
authors.lastname: Spira
authors.forename: H
authors.initials: H
authors.lastname: Parnas
authors.forename: I
authors.initials: I
authors.lastname: Parnas
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002138:Calibration; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D007700:Kinetics; D009132:Muscles / Q000294:innervation* / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes; D018377:Neurotransmitter Agents; C058776:2-(2-(5-carboxy)oxazole)-5-hydroxy-6-aminobenzofuran-N,N,O-triacetic acid; D002118:Calcium; D016257:Fura-2