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KMID : 0378019920350030033
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New Medical Journal
1992 Volume.35 No. 3 p.33 ~ p.44
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A Study for the Chemoreceptive Properites of Group II Afferents in Cat´s Knee Joint
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Abstract
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This experiment was performed to determine whether the group II articular afferents have the chemoreceptive properties or not by observation of the response of them to intra-arterially injected chemicals through articular artery in the cats knee joint. The chemicals used in this study were bradykinin 0.26-26,?g and prostaglandin E2 0.3-30,?g. In addition the effects of prostaglandin E2 for the sensitization of group II articular afferents were observed. Eighteen cats were anesthetized with alpha chloralose and recording were done at 22 single group II articular afferents that had conduction velocities between 20 and 70 m/sec.
The results are as follows. ;
1. The conduction velocities of 22 group II articular afferents fell into the range from 20.7 to 56.3m/second and 6 among them showed spontaneous impulse discharges.
2. All the units showed positive responses to two or more combination of movement stimulus types and the responses were characterized as rapidly adapting or slowly adapting pattern.
3. Nineteen of twenty two units were tested with bradykinin 0.26-26,?g but seven units (36.8%) revealed the increased impulse discharges to the injected bradykinin. The typical response has latency of 11.3±4.5 seconds. duration of 193.4±48.6 seconds and peak discharge of 12.3±5.2 counts/sec. This response was observed mainly in the slowly adapting units.
4. Prostaglandin E2 0.3-30pg directly excited four of sixteen units tested(25.0%). The excitation response had much shorter duration and peak discharge in comparison with that of bradykinin.
5. The sensitizing effects of prostaglandin E2 were found in five of fifteen units(33.3%). In the sensitization, one was the increase in the ongoing spontaneous activities and the other was augmented response to the normal movement stimuli.
To summarize the above results, the group II articular afferents were excited by the chemicals, e.g. bradykinin and prostaglandin E2, and were sensitized by the prostaglandin E2 to the movement stimuli within normal working range. From the fact above it could be concluded that the joint receptors innervated by group II afferents would have the chemoreceptive properties and might play a certain role in joint inflammation.
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