Crayfish stretch receptor: an investigation with voltage‐clamp and ion‐sensitive electrodes.

Abstract

SUMMARY1. The membrane characteristics of the slowly adapting stretch receptor from the crayfish, Asta8us fiuviatilis, were examined with electrophysiological techniques consisting of membrane potential recording, voltage clamp and ion-sensitive microelectrodes.2. The passive membrane current (Ip) following step changes of the membrane potential to levels above 0 mV required more than a minute to decay to a steadystate level.3. The stretch-induced current (SIC, where SIC = total -Ipassive) was not fully developed until the Ip had decayed to a steady state.4. With Ip at the steady state and the stretch-induced current at the 0-current potential, a slow stretch-induced inward current was isolated. The latter reaches a maximum after 1 see of stretch and declines even more slowly after stretch. The I-V relation of the slow current had a negative slope and reversed sign near the resting potential. It is suggested that this current is due to a Cl-conductance change.5. The stretch-induced current, consisting of a rapid transient phase and a steady component can be isolated from the slow stretch-induced current at a holding potential corresponding to the resting potential.6. The SIC-Em relation is non-linear and reverses sign at about +15 mV.7. In a given cell, the reversal potential of the stretch-induced potential change obtained with current clamp coincided with the 0-current potential of the stretchinduced current obtained by voltage clamp. The average value from twenty-six cells was + 13 + 6'5 mV; cell to cell variability seemed to be correlated with dendrite length.8. Tris (mol. wt. 121) or arginine (mol. wt. 174) substituted for Na+ reduces but does not abolish the stretch-induced current.9. The permeability ratios of Tris: Na and arginine: Na were estimated from changes in the 0-current potential as these cations replaced Na+ in the eternal medium. The PTr, :PNa was somewhat higher (0-31) than the Parginine:PN ratio (0.25).10. Changes in the external Ca2+ concentration had no effect on the 0-current potential in Na or Tris saline. However, reducing Ca2+ did augment the stretchinduced current in either saline. A tenfold reduction of Ca2+ increased the conductance (at the 0-current level) about twofold.

Ammonium action on post‐synaptic inhibition in crayfish neurones: implications for the mechanism of chloride extrusion

“…However, the after-hyperpolarization may include conductances other than K+ and thus give an under-estimate of EK (see also Allen et al 1977). Recent measurements of EC1 and EK in the crayfish stretch receptor neurone suggest that EK is 22 mV more negative than Em (Brown et al 1978) but EC,, given as 9 mV less negative than Em, was probably artificially low due to the use of relatively low resistance, 3 M-KCl micro-electrodes. Nevertheless, Ei p s p in the present study was never more than 18 mV more negative than Em under normal conditions.…”

“…However, assuming a 10 % K+ contribution (Sypert & Bidgood, 1977), an EK of86 mV (Brown, Ottoson & Rydqvist, 1978) and a constant Cl-i deviation from the equilibrium level (Martin, appendix to Matthews & Wickelgren, 1979), increasing K+o from 5-4 to 10 mm would decrease the driving force to 62-2 % of the control, whereas the experimentally observed decrease was to 33-1 % (Table 1) (Martin, appendix to Matthews & Wickelgren, 1979) when an increase of K%0 from 5-4 to 10 mm would decrease the driving force to 57 % of the control. It should be noted that the inverse relationship of g9 to Ei.p.s.p.…”

Muscle Receptor Organs in the Crayfish Abdomen: A Student Laboratory Exercise in Proprioception

“…The biophysical properties of these sensory neurons has in part been addressed in their nature of adaptation in the neural activity with a maintained stimulus (Brown et al, 1978;Edwards et al, 1981;Purali, 1997;Rydqvist and Purali,1991;Rydqvist and Swerup, 1991). However, only a few reports address neuromodulation on these sensory receptors and associated muscle fibers (Cooper et al, 2003;Pasztor and Macmillan, 1990).…”

“…activated" channels in neurons function, ionic flow, channel distribution, and density of sensory neurons (Brown et al, 1978;Edwards et al, 1981;Erxleben, 1989;Hunt et al, 1978;Purali and Rydqvist, 1992;Rydqvist and Purali, 1991;Rydqvist and Swerup, 1991;Cooper et al, 2003). The integration of the sensory input from the MRO in one segment can influence other adjoining segments (Eckert, 1961a,b).…”

The effects of serotonin and ecdysone on primary sensory neurons in crayfish

“…This preparation has also provided an understanding of sensory transduction by the activation of "stretch activated" channels in neurons (Erxleben, 1989). In addition, voltage-clamp and patch-clamp studies of the neuronal membrane have provided a fundamental understanding of ionic flow, channel distribution, and density, as well as regional properties of sensory neurons (Brown et al, 1978;Edwards et al, 1981;Erxleben, 1989;Hunt et al, 1978;Purali and Rydqvist, 1992;Rydqvist and Purali, 1991;Rydqvist and Swerup, 1991).…”