Low pH medium induces calcium dependent release of CGRP from sensory nerves of guinea-pig dural venous sinuses.
Low pH medium has been shown to activate the 'efferent' function of capsaicin-sensitive primary sensory neurons. Calcitonin gene-related peptide (CGRP) is released from capsaicin-sensitive afferents of guinea-pig superior sagittal and transverse sinuses (SSTS), by capsaicin or bradykinin. Here, we report that low pH medium produces a remarkable release of CGRP from SSTS, which was dependent on the concentration of hydrogen ions of the medium (pH 7-5). Moreover, the pH 5-evoked release of CGRP-LI was markedly reduced (by about 70%) in a calcium-free medium containing 1 mM EDTA or abolished in samples pre-exposed to 10 microM capsaicin. The present observation that lowering of the pH promotes release of a powerful vasoactive peptide from perivascular capsaicin-sensitive sensory nerves may have some relevance in the pathophysiology of brain injury and migraine headaches.
Fanciullacci
M
M
Institute of Internal Medicine IV, University of Florence, Italy.
Tramontana
M
M
Del Bianco
E
E
Alessandri
M
M
Geppetti
P
P
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D004388:Dura Mater / Q000098:blood supply / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D008297:Male; D009475:Neurons, Afferent / Q000378:metabolism; D009476:Neurons, Efferent / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D014680:Veins / Q000378:metabolism
D015740:Calcitonin Gene-Related Peptide; D011188:Potassium; D002118:Calcium