In the present study 366 patients suffering acute or chronic musculoskeletal pain of different origin were given vibratory stimulation for the pain. Many of the patients had previously had treatments of various kinds without satisfactory relief. The effect of vibratory stimulation was assessed during and after stimulation using a graphic rating scale. Sixty-nine per cent of the patients reported a reduction of pain during vibratory stimulation. The best pain reducing site was found to be either the area of pain, the affected muscle or tendon, the antagonistic muscle or a trigger point outside the painful area. In most patients the best pain reducing effect was obtained when the vibratory stimulation was applied with moderate pressure. To obtain a maximal duration of pain relief the stimulation had to be applied for about 25-45 min.

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.

No abstract

SUMMARY1. An isolated muscle spindle preparation from a tail muscle of cat is described. The afferent response to a ramp-and-hold stretch was recorded in individual axons from identified primary and secondary endings.2. Primary endings exhibit a prominent dynamic response, including an initial burst. They also show a well-maintained static discharge. Secondary endings also show a well-sustained static discharge but generally have a much lower dynamic sensitivity. The response of primary and secondary endings of the isolated spindle are similar to the typical responses seen in vivo in group Ia or group II afferent fibres respectively.3. Following impulse blockade by tetrodotoxin, the receptor potential was recorded from primary and from secondary endings in response to ramp-and-hold stretch.4. During the dynamic phase the receptor potential of primary endings consists of a depolarization which has two components. (a) An initial component occurs early during ramp stretch, depends in rate of rise and amplitude on velocity of stretch and is reduced on repetitive stretch; it appears to be responsible for the initial burst. (b) A late dynamic component, which follows, is also dependent on stretch velocity and produces the late dynamic discharge. At the end of ramp stretch the receptor potential falls, and may undershoot, the static level. There is a subsequent adaptive fall during hold stretch, then a maintained static level of receptor potential. On release from stretch the membrane is hyperpolarized.5. Secondary endings usually show a smaller dynamic response, lacking the initial component seen in primary endings. They also generally lack an undershoot following the ramp and have less of a post-release hyperpolarization.C. C. HUNT AND D. OTTOSON 6. Static levels of receptor potential in both primary and secondary endings are related to amplitude of stretch.7. The receptor potentials of primary and secondary endings account for the major features of the impulse responses of these endings to rampand-hold stretch. In primary endings the dynamic frequencies may also depend upon a sensitivity of the impulse initiating site to rate of change of receptor current.