Inhibition by bradykinin of voltage-activated barium current in a rat dorsal root ganglion cell line: role of protein kinase C.
The whole-cell patch-clamp technique was used to record Ba2+ currents through voltage-activated calcium channels in the clonal dorsal root ganglion cell line F11-B9. The pain-producing peptide bradykinin (BK; 100 nM) reduced the sustained Ba2+ current in F11-B9 cells by 30%. In cultures prelabeled with 3H-arachidonic acid and tested under ionic conditions similar to those used for recording Ba2+ currents, BK also induced a concentration-dependent, transient, 2.7-fold accumulation of 3H-diacylglycerol. Both the elevation of 3H-diacylglycerol and the inhibition of Ba2+ current began within 5 sec following BK exposure, and the effective concentration range of BK was similar for the 2 responses. In whole-cell recordings, extracellularly applied 1-oleoyl-2-acetylglycerol (OAG; 0.5-5 microM) mimicked the degree of block and occluded the block of sustained current by BK. Another protein kinase C (PKC) activator, 1,2-dioctanoylglycerol (diC8), blocked 70-100% of sustained current when applied intracellularly or extracellularly at 5 microM, whereas extracellular application of ethylene glycol dioctanoate (5 microM), an analog reported not to stimulate PKC, inhibited only 14% of sustained current. The pseudosubstrate peptide PKC19-36 (2 microM in pipette) and the lipid staurosporine (100 nM in pipette), both inhibitors of PKC, reduced the effects of maximal concentrations of OAG or BK by 55-60%. Dynorphin A applied intracellularly (2 microM) as a control for nonspecific effects of PKC19-36 did not inhibit the block of sustained current by BK. These data are consistent with the hypothesis that BK inhibits whole-cell sustained Ba2+ current in F11-B9 cells via a mechanism that involves activation of PKC.
Boland
L M
LM
Curriculum in Neurobiology, University of North Carolina, School of Medicine, Chapel Hill 27599-7365.
Allen
A C
AC
Dingledine
R
R
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000502:physiology*; D001920:Bradykinin / Q000494:pharmacology*; D002460:Cell Line; D004075:Diglycerides / Q000096:biosynthesis / Q000494:pharmacology; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D019311:Staurosporine
D000470:Alkaloids; D004075:Diglycerides; C044295:1,2-dioctanoylglycerol; D001464:Barium; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D019311:Staurosporine; D001920:Bradykinin