Current-clamp experiments, effects

Effects of pyrethroid molecules on isolated axons (current-clamp experiments). 

Subsequently, serotonin was shown to affect responses to excitatory amino acids in rat neocortical neurons, in cells of the ventrobasal thalamus, dorsal horn neurons, and rat locus coeruleus neurons (Aston-Jones et al. 1991 S. A. Eaton and Salt 1989 Murase et al. 1990 Read et al. 1990 J. N. Reynolds et al. 1988]. Whether the modulatory effect of serotonin is to enhance or attenuate the effect of the excitatory amino acid appears to depend on the brain region investigated. Also, many of the experiments used extracellular recording techniques, although Sizer et al. (1992] used intracellular current clamp in vitro experiments to investigate neurons of the rat entorhinal cortex and neocortex. In the entorhinal cortex and neocortex, the predominant effects of serotonin were to reduce and enhance, respectively, the response to excitatory amino acids. 

One of the key features of ABA enhancement of Ik,oui is that it persists even when cytosolic Ca" concentrations are buffered to low levels by the inclusion of EGTA in the patch pipette solution during whole cell reeording. This suggests that elevated [Ca ],., is not involved in the activation of Ik.oui t>y ABA. Indeed, when [Ca ], is experimentally elevated from approximately 2 nM to 200 nM in whole-cell patch clamp experiments, current through outward K channels is reduced [72], an effect which would oppose stomatal closure. At higher [Ca ],.y,s, outward current shows little Ca -sensitivity [23]. More recently, it has been shown that Ik oui sensitive to cytoplasmic pH. Its regulation by pH has consequences for ABA-induced closure, and will be discussed in Section... 

Voltage clamp experiments using identified neurons, dorsal unpaired median (DUM) neurons from the terminal abdominal ganglion of P. americana, demonstrated that DCJW inhibited the peak Na+ current with an IC50 of 28 nM [38]. DCJW (7) (100 mv[) induced a hyperpolarization of DUM neurons associated with block of background Na channels involved in maintenance of the resting potential. While the peak Na+ current was inhibited, DCJW had no effect on either activation or inactivation kinetics (Fig. 29.4.13). Zhao et al. (2005) similarly... 

Hescheler J, Delpiano MA, Acker H, Pietraschka F. Ionic currents on type-I cells of the rabbit carotid body measured by voltage-clamp experiments and the effect of hypoxia. Brain Res 1989 486(l) 79-88. 

---