A pressure system for intracellular and extracellular ejections of picoliter volumes

McCaman, Richard E.; McKenna, David G.; Ono, Joyce K.

doi:10.1016/0006-8993(77)90138-x

Cited by 139 publications

(46 citation statements)

References 9 publications

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“…Decalcified larvae were injected with a small volume (about 6 nl or about 10% of larval volume) of the test solution using a Picospritzer II (General Valve Corporation) (McCaman et al, 1977). The injection site was approximately 50 μm dorsal to the statocyst, just under the epidermis.…”

Section: Injection Experimentsmentioning

confidence: 99%

Serotonin Injections Induce Metamorphosis in Larvae of the Gastropod Mollusc Ilyanassa obsoleta

Couper

Leise

1996

The Biological Bulletin

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Abstract:Bath-applied serotonin (5-HT) induces competent larvae of the marine snail Ilyanassa obsoleta to metamorphose. Previously, the mode of action of 5-HT, whether as an external ligand or as an internal neurotransmitter, was unknown. Larvae were injected with 10 -4 M 5-HT and other pharmacological agents to provide evidence that serotonergic neurons are necessary for metamorphosis in Ilyanassa larvae and that serotonin functions as a neurotransmitter or neuromodulator during this process. About 50% of 5-HT-injected animals metamorphose within 48 hours. Fluoxetine, a 5-HT re-uptake inhibitor, and alpha-methy1-5-hydroxytryptamine (αm5HT), a 5-HT agonist, were also effective inducers of metamorphosis. Gramine (3-[dimethyl-aminomethyl]indole), a 5-HT antagonist, inhibited the inductive activity of 5-HT, while the amino acid gamma-aminobutyric acid (GABA) resulted in rates of morphological restructuring similar to those of controls. Collectively, the results of our experiments support the idea that serotonergic neurons are active during larval metamorphosis of Ilyanassa and that 5-HT does not induce metamorphosis by binding to epidermal chemoreceptors.

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Section: Injection Experimentsmentioning

confidence: 99%

Serotonin Injections Induce Metamorphosis in Larvae of the Gastropod Mollusc Ilyanassa obsoleta

Couper

Leise

1996

The Biological Bulletin

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“…Pressure-ejection from glass micropipettes has been reported to release drug in an amount linearly releated to the product of pressure and duration of ejection (McCaman et al, 1977;Sakai et al, 1979). The magnitude of drug effect has also been reported to be a function of these parameters of pressure-ejection .…”

Section: Construction and Analysis Of Dose-response Curvesmentioning

confidence: 99%

Investigation of the failure of parenterally administered haloperidol to antagonize dopamine released from micropipettes in the caudate

Johnson¹,

Hoffer²,

Freedman³

1986

J. Neurosci.

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An anomaly in the experimental data underlying the theory that neuroleptics act by blockade of dopaminergic neurotransmission is the repeatedly demonstrated failure in several laboratories of parenterally administered neuroleptics to antagonize electrophysiologic actions of locally applied dopamine (DA) in striaturn. This failure is enigmatic since many investigators have successfully demonstrated antagonism when both dopamine and neuroleptic are applied directly to striatal neurons by microiontophoresis. We used multibarrel micropipettes to pressure-eject DA agonists onto rat caudate neurons while observing the ability of parenterally administered haloperidol to block the inhibitory actions of dopaminergic agonists on neuronal activity. Experiments performed at times of maximal behavioral effect of haloperidol did not demonstrate agonist-antagonist interaction. This result has been obtained by four other teams of investigators. A variety of pharmacologic manipulations were employed to help solve this enigma. Acute treatment with reserpine and a-methyl-paratyrosine, performed to minimize any possible interference by endogenous DA, did not permit blockade of dopamine by haloperidol. To see if this failure of antagonism could be generalized to other DA agonists, apomorphine, amphetamine, and phencyclidine (PCP) were also investigated. Although the direct dopaminergic agonist apomorphine was not antagonized by haloperidol, the indirect DA agonist PCP was successfully antagonized. Amphetamine, which has both direct and indirect actions when applied locally, was not antagonized. Antagonism of direct agonists was demonstrated in rats with unilateral 6-hydroxydopamine-induced lesions of the nigrostriatal pathway. In these preparations, parenterally administered haloperidol reversed the receptor-mediated supersensitivity to the inhibitory effects of locally applied DA and apomorphine. These data suggest that in caudate there exist postsynaptic receptors that are more sensitive to haloperidol than those receptors usually activated by DA released into the neuronal milieu from micropipettes. We suggest that PCP's indirect action on endogenous DA in presynaptic terminals results in specific interaction with these receptors. We further suggest that the postsynaptic receptors most sensitive to blockade by haloperidol may also be those receptors that increase in number following denervation. Failure to demonstrate antagonism of direct DA agonists in the absence of supersensitivity suggests that locally applied DA does not normally contact postsynaptic dopami-

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“…The volume injected into the cell was controlled by a system similar to the one described by McCaman, McKenna & Ono (1977), which permitted an estimate of intracellular concentration. Fast green (2%) was added to the solution for confirmation of successful ejection (Bowling, Nicholls & Parnas, 1978).…”

Section: Sparteine and Leech Neuronesmentioning

confidence: 99%

Segregation of leech neurones by the effect of sparteine on action potential duration.

Kleinhaus¹

1980

The Journal of Physiology

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SUMMARY1. Sparteine (SPT) and 3-or 4-aminopyridine, were applied to leech segmental ganglia and the electrophysiological responses ofthe Retzius (R) and sensory neurones responding to pressure (P), touch (T), and noxious (N) stimuli analysed.2. SPT 0*05-0*5 mm when presented via the bath to the whole ganglion prolonged the action potentials of these neurones to characteristically different degrees; the cells were clearly segregated in the order R > N > P > T at 0 5 mm, regardless of exposure time.3. The plateau of the prolonged action potentials in the R and N cells was sustained by either Ca or Sr and was blocked by Mn, in normal or Na-free Ringer. These responses were similar to those seen in the same cell types with TEA under the same condition.4. The SPT prolongation of action potentials was favoured by alkalinization of the Ringer solution. This implies that the drug acted in its uncharged form. SPT was ineffective when applied by pressure into the somata of these four neurones. This may be because SPT was charged at the intracellular pH or because it acted at some external membrane site.5. The aminopyridines when applied in the bath had no effect on the repolarization of these four neurones.6. These results suggest that TEA and SPT probably act on repolarization by similar mechanisms. The parameter of membrane function principally affected is probably a K current which contributes to repolarization to different degrees in the four cells and which may be activated by Ca.

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A pressure system for intracellular and extracellular ejections of picoliter volumes

Cited by 139 publications

References 9 publications

Serotonin Injections Induce Metamorphosis in Larvae of the Gastropod Mollusc Ilyanassa obsoleta

Serotonin Injections Induce Metamorphosis in Larvae of the Gastropod Mollusc Ilyanassa obsoleta

Investigation of the failure of parenterally administered haloperidol to antagonize dopamine released from micropipettes in the caudate

Segregation of leech neurones by the effect of sparteine on action potential duration.

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