Fatigue refers to the decrement of response seen with repeated stimulation and is a prominent attribute of nociceptors. Whether @entity1295 in nociceptors involves transduction, spike initiation, or conduction mechanisms is unknown. We investigated systematically how electrical, mechanical, and heat conditioning stimuli (eCS, mCS, @entity4674 ) affected the subsequent response to a test-heat stimulus applied 5 sec later to the receptive field of cutaneous nociceptors. Standard teased-fiber techniques were used to record from mechano-heat-sensitive @entity7183 afferents in the anesthetized monkey. The eCS was applied to the nerve trunk, whereas the @entity4674 and mCS were applied to the heat-test site. For the eCS, the number of pulses rather than frequency of stimulation determined the level of @entity1295 . Fatigue varied inversely with the time interval between the eCS and the test stimulus. For comparable responses from the @entity4674 , the magnitude of @entity1295 was less after the mCS than after the eCS. The mCS (but not the eCS) sometimes evoked a paradoxical increase in response to the test-heat stimulus. Recovery from @entity1295 was significantly faster after the eCS and mCS than the @entity4674 . The paradoxical enhancement after the mCS probably results from temporal summation of generator potentials produced by mechanical and heat stimulation and suggests that the time constant of the generator potential is on the order of seconds. Concurrent enhancement- @entity1295 effects may also explain why @entity1295 was less after the mCS than the eCS. The dependency of recovery from @entity1295 on the modality of the @entity4674 suggests that @entity1295 results from transduction-spike initiation mechanisms.

Fatigue and paradoxical enhancement of heat response in XXXX nociceptors from cross-modal excitation.

@entity7183 :: ('10185', 'Species') :: ['C-fiber'] @entity4674 :: ('54205', 'Gene') :: ['CS', 'hCS'] @entity1295 :: ('MESH:D005221', 'Disease') :: ['fatigue']
@entity7183 :: (10185,Species) :: ['C-fiber']
