Release of calcitonin gene-related peptide-like (CGRP-LI) immunoreactivity from rat isolated soleus muscle by low pH, capsaicin and potassium.
Capsaicin (10 microM), KCl (80 mM) or superfusion with a low pH medium (pH 5 or 6) produced a significant increase of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) outflow from the superfused rat isolated soleus muscle. CGRP-LI outflow produced by capsaicin or pH 5 medium was totally abolished in a calcium free medium containing EDTA (1 mM) and the effect of pH 5 medium was prevented by a previous application of capsaicin. Ruthenium red (10 microM) produced a marked inhibition of CGRP-LI release produced by capsaicin or pH 5 medium (69 and 84%, resp.), without affecting that evoked by KCl. These findings demonstrate that protons activate capsaicin-sensitive primary afferents in rat skeletal muscle through a Ruthenium red-sensitive mechanism. Proton-induced CGRP-LI release in skeletal muscle could be of relevance during exercise and/or skeletal muscle ischemia.
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002211:Capsaicin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D009132:Muscles / Q000378:metabolism*; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology*; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D012430:Ruthenium Red / Q000494:pharmacology*
D015220:Calcium Channels; D011522:Protons; D012430:Ruthenium Red; D011189:Potassium Chloride; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin