Effect of tooth temperature on activities of slowly adapting periodontal mechanoreceptors in the cat.
The mass response of a nerve bundle and the unitary discharges from a functional single nerve fibre evoked by mechanical stimulation of the upper canine tooth were recorded from the superior alveolar nerves of 10 anaesthetized cats. When the pulpal cavity of the mechanically stimulated tooth was perfused with a 0.9% NaCl solution at temperatures from 10 to 45 degrees C, the mass response of the nerve bundle to that stimulation increased linearly with the rise in perfusate temperature (hereafter, tooth temperature). In the unitary discharge recordings, the activities of 30 (88%) of 34 slowly adapting periodontal mechanosensitive units were modulated by tooth temperature. The optimal temperature, at which the periodontal mechanoreceptor shows extreme excitation by mechanical tooth stimulation, was distributed widely from 10 to < or = 45 degrees C with a peak at < or = 45 degrees C. A shift in tooth temperature away from the optimal value caused a decrease in, or sometimes the disappearance of, the response. This decrease was the result of the decrease in the excitability of the periodontal mechanoreceptor; i.e. an increase in threshold stimulus intensity and a shortening of the adaptation time to sustained pressure applied to the tooth.
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Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan.
Karita
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D000222:Adaptation, Physiological; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D002415:Cats; D003481:Cuspid; D003786:Dental Pulp Cavity / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D008442:Maxillary Nerve / Q000502:physiology; D008465:Mechanoreceptors / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D010519:Periodontium / Q000294:innervation*; D010812:Physical Stimulation; D012684:Sensory Thresholds / Q000502:physiology; D013314:Stress, Mechanical; D013816:Thermodynamics; D014070:Tooth / Q000502:physiology*