NICOTINE-EVOKED AND CAPSAICIN-EVOKED, BUT NOT POTASSIUM-EVOKED CGP-RELEASE FROM CULTURED GUINEA-PIG SPINAL GANGLIA IS INHIBITED BY RUTHENIUM RED

In the present study we have investigated the effects of nicotine, cap saicin, potassium, glutamate and aspartate on release of calcitonin ge ne-related peptide (CGRP)-like immunoreactivity (-LI) from guinea-pig dorsal root ganglion (DRG) cultures. In addition the possible influenc e of Ruthenium red (RR), neuropeptide Y (NPY) and noradrenaline (NA) o n the CGRP-LI outflow has been evaluated. Nicotine, capsaicin and pota ssium, but not glutamate or aspartate, evoked a Ca2+-dependent increas e in the culture medium, suggesting release of CGRP-LI. RR inhibited t he effect of both capsaicin and nicotine but did not influence potassi um-induced CGRP-LI release. Furthermore, the nicotine- but not capsaic in-evoked CGRP-LI release was inhibited by NPY. It is concluded that D RG cultures represent an experimental model where regulation of CGRP-L I release can be studied. The ability of RR to inhibit not only capsai cin but also nicotine effects indicate that the proposed selectivity o f RR may depend on the agent used to evoke peptide release and/or conc entrations used.