Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electronic Resource  (2)
  • Aplysia neuron  (1)
  • barium  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Influences of trypsin and collagenase on acetylcholine responses of physically isolated single neurons ofAplysia californica (1990)
    Springer
    Cellular and molecular neurobiology 10 (1990), S. 193-205 
    Details
    ISSN: 1573-6830
    Keywords: acetylcholine ; Aplysia neuron ; cholinesterase ; collagenase ; trypsin ; voltage clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The influences of enzyme treatments (trypsin and collagenase) on responses to perfused acetylcholine were examined on physically isolated singleAplysia neurons, using the voltage-clamp, internal perfusion, and rapid external perfusion technique. 2. During treatment with trypsin (0.025 to 0.1%) for 10 to 30 min at room temperature (22 to 25°C), the peak amplitude of the Na current induced by acetylcholine increased in a time- and dose-dependent manner, and the decay in the continued presence of acetylcholine was slowed. This effect of trypsin treatment was irreversible after washing for 60 min without enzyme. 3. Edrophonium, a cholinesterase inhibitor, has previously been shown to augment the Na acetylcholine response in this preparation by inhibition of acetylcholinesterase. After treatment of the neuron with trypsin, the augmentation after edrophonium was abolished. Furthermore, in the presence of edrophonium, trypsin also failed to increase the response. The dose-response curve for acetylcholine after treatment of trypsin was similar to that in the presence of edrophonium. These results suggest that the modification of the current response by trypsin is a result of removal of cholinesterase activity from the membrane. 4. In contrast to the effects of trypsin, collagenase (0.03 to 0.1%) for 10 to 60 min did not change the current amplitude of the acetylcholine response. However, collagenase treatment did alter the kinetics of the acetylcholine response in a dose-dependent manner, in that the rate of decay was accelerated. A similar acceleration was seen in the acetylcholine responses on other neurons which were due to Cl or K currents, suggesting that the effect was independent on the type of channel. This effect of collagenase was reversible after 30 to 60 min of washing of the neuron. 5. In the presence of edrophonium or after the treatment with trypsin, collagenase still accelerated the current kinetics of the acetylcholine response, indicating that cholinesterase activity is not related to this effect. Furthermore, heated collagenase (presumably inactivated) had a similar action, suggesting that the enzymatic activity of collagenase is not related to the modification of the response. 6. These results suggest thatAplysia acetylcholinesterase is sensitive to trypsin but not to collagenase. However, the preparation of collagenase used in these studies contains some factor which alters the response to acetylcholine, but this effect is reversible and unrelated to enzymatic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00734573
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Asymmetric distribution of acetylcholine receptors and M channels on prepyriform neurons (1983)
    Springer
    Cellular and molecular neurobiology 3 (1983), S. 163-181 
    Details
    ISSN: 1573-6830
    Keywords: receptor distribution ; acetylcholine ; prepyriform cortex ; basal dendrites ; pyramidal neurons ; potentiation ; M currents ; muscarinic receptors ; brain slices ; barium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The responses of pyramidal neurons of rat prepyriform cortex to ionophoretic application of acetylcholine (ACh) were studied in a submerged, perfused brain slice. 2. ACh excited some neurons but only if applied to an area near to the cut surface of the slice. This area contained the basal dendrites of the pyramidal cells and some cell bodies. No excitation was seen if ACh was applied at depths of 250µm or more from the cut surface, an area which contained only apical dendrites, although the apical dendrites were very sensitive to excitatory amino acids such as aspartate (Asp) and glutamate (Glu). 3. On all neurons which did not discharge to ionophoretic application of ACh, ACh potentiated the response to Glu and Asp. No potentiation of amino acid responses was obtained on apical dendrites. The potentiation had a time course similar to that of the discharge of neurons which fired to ACh. This observation suggests that pyramidal neurons have receptors for ACh on basal but not apical dendrites. 4. The ACh response in the basal dendrite-soma region was elicted by pilocarpine and blocked by atropine but not curare. This was true whether the response studied was direct excitation or potentiation of the response to an amino acid. 5. The ACh response was associated with a voltage-dependent increase in membrane resistance which had a slow time course and appeared to be due to a turning off of an M current, as described by Brown and Adams (1980) in sympathetic ganglion cells. The effects of ACh were minimal at the resting potential but increased with depolarization. ACh had no effect on the current-voltage relation of the cell, except at depolarized potentials of less than -60 mV. 6. Ionophoretic application of Ba2+ to the basal dendritic region resulted in potentiation of the amino acid responses and sometimes induced a discharge similar to that of ACh. Since Ba2+ mimics the ACh response, presumably by a direct blockade of the M channel, the effects of Ba2+ on apical dendrites were tested to determine whether these dendrites contain M channels associated with a transmitter receptor other than ACh. However, Ba2+ did not induce potentiation in apical dendrites, suggesting that M channels are also restricted to the basal dendrites or cell bodies. 7. The potentiation of a response to a depolarizing constant-current pulse was comparable in degree and time course to that of amino acid responses, indicating that the ACh potentiation of the amino acid responses is a predictable augmentation of any input which brings the membrane potential into the range of M-channel activation. 8. The segregation of ACh receptors to a discrete portion of the cell suggests that they are functional receptors and may be part of a physiologic arrangement which directs different afferent inputs to different portions of the dendritic tree. Such segregation of receptors may also occur on other neurons with distributed inputs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00735280
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...