Effects of capsaicin and bradykinin on afferent fibers with ending in skeletal muscle. Export

@article{citeulike:1140257, abstract = {Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 microgram/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (A delta fiber) endings. By contrast, bradykinin (0.5-1.5 microgram/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 +/- 0.1 to a peak of 9.3 +/- 1.4 imp/sec. Firing started 6 +/- 1 seconds after injection and remained above control levels for 24 +/- 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents.}, author = {Kaufman, M. P. and Iwamoto, G. A. and Longhurst, J. C. and Mitchell, J. H.}, citeulike-article-id = {1140257}, citeulike-linkout-0 = {http://view.ncbi.nlm.nih.gov/pubmed/7053873}, citeulike-linkout-1 = {http://www.hubmed.org/display.cgi?uids=7053873}, comment = {Capsaicin CAP-SEN-Neu Box}, issn = {0009-7330}, journal = {Circ Res}, keywords = {afferent, bradykinin, capsaicin, muscle}, month = {January}, number = {1}, pages = {133--139}, posted-at = {2007-03-05 00:27:26}, priority = {2}, title = {Effects of capsaicin and bradykinin on afferent fibers with ending in skeletal muscle.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/7053873}, volume = {50}, year = {1982} }

TY - JOUR ID - citeulike:1140257 L3 - citeulike-article-id:1140257 N2 - Capsaicin, injected into the arterial supply of the skinned hindlimb of dogs, evokes reflex increases in cardiovascular function. Moreover, the cardiovascular reflexes evoked by capsaicin are very similar to those evoked by static exercise. The afferent fibers initiating these reflex increases have not been identified electrophysiologically, although their endings are believed to be located in skeletal muscle. We have, therefore, attempted to determine which afferent fibers are stimulated by capsaicin. In anesthetized dogs, we recorded impulses from afferent fibers with endings in either the gastrocnemius or gracilis muscles and injected capsaicin (10-30 microgram/kg) into the abdominal aorta. Capsaicin stimulated 24 of 34 group IV (C fiber) endings, but only 5 of 19 group III (A delta fiber) endings. By contrast, bradykinin (0.5-1.5 microgram/kg) stimulated 17 of 33 group IV endings and 9 of 19 group III endings. Impulse activity for the 24 group IV afferents stimulated by capsaicin increased from 0.7 +/- 0.1 to a peak of 9.3 +/- 1.4 imp/sec. Firing started 6 +/- 1 seconds after injection and remained above control levels for 24 +/- 5 seconds. Capsaicin had no significant effect on the firing rate of 30 group I and II muscle afferents. Our results suggest that group IV muscle afferents are primarily responsible for causing the reflex increases in cardiovascular function evoked by injecting capsaicin into the arterial supply of the skinned hindlimb of dogs. Moreover, capsaicin is likely to be a useful pharmacological tool with which to determine the reflex autonomic effects caused by stimulation of group IV muscle afferents. IS - 1 JF - Circ Res SN - 0009-7330 EP - 139 TI - Effects of capsaicin and bradykinin on afferent fibers with ending in skeletal muscle. VL - 50 SP - 133 KW - afferent KW - bradykinin KW - capsaicin KW - muscle N1 - Capsaicin CAP-SEN-Neu Box AU - Kaufman, MP AU - Iwamoto, GA AU - Longhurst, JC AU - Mitchell, JH PY - 1982/01// UR - http://view.ncbi.nlm.nih.gov/pubmed/7053873 ER -