1978
DOI: 10.1016/s0006-3495(78)85352-1
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Response of acetylcholine receptors to photoisomerizations of bound agonist molecules

Abstract: In these experiments, agonist-induced conductance is measured while a sudden perturbation is produced at the agonist-receptor binding site. A voltage-clamped Electrophorus electroplaque is exposed to trans-Bis-Q, a potent agonist. Some channels are open; these receptors have bound agonist molecules. A light flash isomerizes 3(-35)% of the trans-Bis-Q molecules to their cis form, a far poorer agonist. This causes a rapid decrease of membrane conductance (phase 1), followed by a slower increase (phase 2). Phase … Show more

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Cited by 28 publications
(55 citation statements)
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“…These molecules have two crucial properties: (a) they are photoisomerizable, as described above; (b) two configurations differ in their pharmacological properties. THE AGONIST, BIS-Q At the nerve-muscle and nerve-electroplaque synapses of several South American and African fishes, trans-Bis-Q acts as a potent but typical nicotinic agonist at concentrations on the order of 10 -7 M (13,63,65,81,113). At 10°C and a membrane potential of -75 mV, it interacts with acetylcholine receptors to open channels with a conductance of 26 ps and a lifetime of 4 msec;~ both these values arẽ Known rticotirdc agonists induce channels with roughly a tenfold range of durations when tested under identical conditions.…”
Section: (86)mentioning
confidence: 99%
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“…These molecules have two crucial properties: (a) they are photoisomerizable, as described above; (b) two configurations differ in their pharmacological properties. THE AGONIST, BIS-Q At the nerve-muscle and nerve-electroplaque synapses of several South American and African fishes, trans-Bis-Q acts as a potent but typical nicotinic agonist at concentrations on the order of 10 -7 M (13,63,65,81,113). At 10°C and a membrane potential of -75 mV, it interacts with acetylcholine receptors to open channels with a conductance of 26 ps and a lifetime of 4 msec;~ both these values arẽ Known rticotirdc agonists induce channels with roughly a tenfold range of durations when tested under identical conditions.…”
Section: (86)mentioning
confidence: 99%
“…Annual Reviews www.annualreviews.org/aronline identical to those measured with acetylchohne itself under the same conditions (113). The rate constant for opening increases with trans-Bis-Q concentration (65,81). The dose-response curve is sigmoid, with a Hill slope very near 2 (93).…”
Section: (86)mentioning
confidence: 99%
“…However, current after a light flash did not decrease rapidly in fish muscle; there was only a relatively slow (tens of milliseconds) decrease in current resembling 'phase 3. ' Nass et al (1978) showed an overshoot of current following a flash in Fig. 4a and b and Fig.…”
Section: Discussionmentioning
confidence: 90%
“…These flashes converted ci8-Bis-Q (the non-agonist configuration) to trans-Bis-Q (the agonist configuration). The optical set-up is described by Nass et al (1978) with these differences: the flash tube was arranged above a compound microscope so that the flash passed through the microscope objective and was focused onto the muscle as a circle one to two millimetres in diameter. In this way, the one to two millimetre-long fibre under study was exposed to a concentration jump of tran8a-Bis-Q.…”
Section: Methodsmentioning
confidence: 99%
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