The ionic mechanism for 5-hydroxytryptamine inhibition on retzius cells of the leech Hirudo medicinalis

Intracellular Chloride Activity and the Effect of 5‐Hydroxytryptamine on the Chloride Conductance of Leech Retzius Neurons

“…Under voltageclamp conditions the reversal potential of the 5-HT-induced membrane current agrees well with the chloride equilibrium potential. The observations agree with the hypothesis of Walker and Smith (1973) who suggested that 5-HT increases the C1-conductance of Retzius neurons, which was directly shown by Lessmann and Dietzel (1991) for Retzius neurons in primary culture with the whole-cell patch-clamp technique. By this mechanism 5-HT could inhibit activity of Retzius neurons, which is involved in behavioural responses of the animal (Kristan and Nusbaum, 1983;Lent and Dickinson, 1984).…”

“…This indicates that 5-HT activates a CIconductance. This is consistent with previous recordings of CI--dependent voltage responses in this cell upon 5-HT application in situ (Walker and Smith, 1973) and in vivo (Drapeau er al., 1989), and confirms that 5-HT induces CI-currents in leech Retzius neurons in primary culture (Lessmann and Dietzel, 1991).…”

“…This is in good agreement with the direct internal C1-measurements using a hypertonic saline with the same C1-concentration as the one employed by Walker and Smith (1973). The difference between the membrane potential and the C1-equilibrium potential and the slight increase in aCl, after depolarizing the cell membrane by current injection indicate a low C1-conductance of the resting Retzius cell membrane.…”

Intracellular Chloride Activity and the Effect of 5‐Hydroxytryptamine on the Chloride Conductance of Leech Retzius Neurons

“…Under voltageclamp conditions the reversal potential of the 5-HT-induced membrane current agrees well with the chloride equilibrium potential. The observations agree with the hypothesis of Walker and Smith (1973) who suggested that 5-HT increases the C1-conductance of Retzius neurons, which was directly shown by Lessmann and Dietzel (1991) for Retzius neurons in primary culture with the whole-cell patch-clamp technique. By this mechanism 5-HT could inhibit activity of Retzius neurons, which is involved in behavioural responses of the animal (Kristan and Nusbaum, 1983;Lent and Dickinson, 1984).…”

“…This indicates that 5-HT activates a CIconductance. This is consistent with previous recordings of CI--dependent voltage responses in this cell upon 5-HT application in situ (Walker and Smith, 1973) and in vivo (Drapeau er al., 1989), and confirms that 5-HT induces CI-currents in leech Retzius neurons in primary culture (Lessmann and Dietzel, 1991).…”

“…This is in good agreement with the direct internal C1-measurements using a hypertonic saline with the same C1-concentration as the one employed by Walker and Smith (1973). The difference between the membrane potential and the C1-equilibrium potential and the slight increase in aCl, after depolarizing the cell membrane by current injection indicate a low C1-conductance of the resting Retzius cell membrane.…”

Development of serotonin-induced ion currents in identified embryonic Retzius cells from the medicinal leech (Hirudo medicinalis)

“…In the case of a significant contribution of monovalent cations to the 5-HT-mediated response, the reversal potential for the combination InCl/Ringer's should be shifted to positive potentials relative to InCl/ExCl. Because the measured shift did not exceed the calculated shift in EC,, these results confirm the finding that Retzius cells respond to 5-HT application predominantly by Cl currents (Walker and Smith, 1973;Cemerikic et al, 1985). With Cll in external and internal solutions, currentvoltage relationships were approximately linear around the reversal potential, and slope conductances could be evaluated.…”

Selective Serotonin Reuptake Inhibitors Induce Spontaneous Interneuronal Activity in the Leech Nervous System

“…8C summarize the results obtained from this series of experiments. The linear regressions in the graphs indicate that the responses of Rz and AE reversed at around Ϫ70 mV, suggesting that they were produced by the activation of a chloride conductance (Walker and Smith 1973). This observation agrees with previous studies showing that exogenous 5-HT causes the activation of a chloride current in Rz neurons (Munsch and Schlue 1993;Walker and Smith 1973) and in other neurons (Henderson 1983;Sanchez-Armass et al 1991).…”

Intracellular Chloride Activity and the Effect of 5‐Hydroxytryptamine on the Chloride Conductance of Leech Retzius Neurons

“…Under voltageclamp conditions the reversal potential of the 5-HT-induced membrane current agrees well with the chloride equilibrium potential. The observations agree with the hypothesis of Walker and Smith (1973) who suggested that 5-HT increases the C1-conductance of Retzius neurons, which was directly shown by Lessmann and Dietzel (1991) for Retzius neurons in primary culture with the whole-cell patch-clamp technique. By this mechanism 5-HT could inhibit activity of Retzius neurons, which is involved in behavioural responses of the animal (Kristan and Nusbaum, 1983;Lent and Dickinson, 1984).…”

“…This indicates that 5-HT activates a CIconductance. This is consistent with previous recordings of CI--dependent voltage responses in this cell upon 5-HT application in situ (Walker and Smith, 1973) and in vivo (Drapeau er al., 1989), and confirms that 5-HT induces CI-currents in leech Retzius neurons in primary culture (Lessmann and Dietzel, 1991).…”

“…This is in good agreement with the direct internal C1-measurements using a hypertonic saline with the same C1-concentration as the one employed by Walker and Smith (1973). The difference between the membrane potential and the C1-equilibrium potential and the slight increase in aCl, after depolarizing the cell membrane by current injection indicate a low C1-conductance of the resting Retzius cell membrane.…”

Development of serotonin-induced ion currents in identified embryonic Retzius cells from the medicinal leech (Hirudo medicinalis)

“…In the case of a significant contribution of monovalent cations to the 5-HT-mediated response, the reversal potential for the combination InCl/Ringer's should be shifted to positive potentials relative to InCl/ExCl. Because the measured shift did not exceed the calculated shift in EC,, these results confirm the finding that Retzius cells respond to 5-HT application predominantly by Cl currents (Walker and Smith, 1973;Cemerikic et al, 1985). With Cll in external and internal solutions, currentvoltage relationships were approximately linear around the reversal potential, and slope conductances could be evaluated.…”

Selective Serotonin Reuptake Inhibitors Induce Spontaneous Interneuronal Activity in the Leech Nervous System

“…8C summarize the results obtained from this series of experiments. The linear regressions in the graphs indicate that the responses of Rz and AE reversed at around Ϫ70 mV, suggesting that they were produced by the activation of a chloride conductance (Walker and Smith 1973). This observation agrees with previous studies showing that exogenous 5-HT causes the activation of a chloride current in Rz neurons (Munsch and Schlue 1993;Walker and Smith 1973) and in other neurons (Henderson 1983;Sanchez-Armass et al 1991).…”

Intracellular Chloride Activity and the Effect of 5‐Hydroxytryptamine on the Chloride Conductance of Leech Retzius Neurons

“…Under voltageclamp conditions the reversal potential of the 5-HT-induced membrane current agrees well with the chloride equilibrium potential. The observations agree with the hypothesis of Walker and Smith (1973) who suggested that 5-HT increases the C1-conductance of Retzius neurons, which was directly shown by Lessmann and Dietzel (1991) for Retzius neurons in primary culture with the whole-cell patch-clamp technique. By this mechanism 5-HT could inhibit activity of Retzius neurons, which is involved in behavioural responses of the animal (Kristan and Nusbaum, 1983;Lent and Dickinson, 1984).…”

“…This indicates that 5-HT activates a CIconductance. This is consistent with previous recordings of CI--dependent voltage responses in this cell upon 5-HT application in situ (Walker and Smith, 1973) and in vivo (Drapeau er al., 1989), and confirms that 5-HT induces CI-currents in leech Retzius neurons in primary culture (Lessmann and Dietzel, 1991).…”

“…This is in good agreement with the direct internal C1-measurements using a hypertonic saline with the same C1-concentration as the one employed by Walker and Smith (1973). The difference between the membrane potential and the C1-equilibrium potential and the slight increase in aCl, after depolarizing the cell membrane by current injection indicate a low C1-conductance of the resting Retzius cell membrane.…”

Development of serotonin-induced ion currents in identified embryonic Retzius cells from the medicinal leech (Hirudo medicinalis)

“…In the case of a significant contribution of monovalent cations to the 5-HT-mediated response, the reversal potential for the combination InCl/Ringer's should be shifted to positive potentials relative to InCl/ExCl. Because the measured shift did not exceed the calculated shift in EC,, these results confirm the finding that Retzius cells respond to 5-HT application predominantly by Cl currents (Walker and Smith, 1973;Cemerikic et al, 1985). With Cll in external and internal solutions, currentvoltage relationships were approximately linear around the reversal potential, and slope conductances could be evaluated.…”

Selective Serotonin Reuptake Inhibitors Induce Spontaneous Interneuronal Activity in the Leech Nervous System

“…8C summarize the results obtained from this series of experiments. The linear regressions in the graphs indicate that the responses of Rz and AE reversed at around Ϫ70 mV, suggesting that they were produced by the activation of a chloride conductance (Walker and Smith 1973). This observation agrees with previous studies showing that exogenous 5-HT causes the activation of a chloride current in Rz neurons (Munsch and Schlue 1993;Walker and Smith 1973) and in other neurons (Henderson 1983;Sanchez-Armass et al 1991).…”