Dibutyryl cGMP raises cytosolic concentrations of Ca2+ in cultured nodose ganglion neurons of the rabbit.

The effect of dibutyryl cGMP (dbcGMP), a membrane permeant cGMP analogue, on cytosolic concentrations of Ca2+ ([Ca2+]i) was studied in cultured nodose ganglion neurons of the rabbit using fura-2AM and microfluorometry. Application of dbcGMP (10-1000 microM) increased [Ca2+]i in 42% of neurons (n=67). The effect was observed in a dose-dependent fashion. The threshold dose was 100 microM and the increase at 500 microM averaged 117+/-8%. Removal of extracellular Ca2+ abolished the dbcGMP effect. Application of Ni2+ (1 mM) or neomycin (50 microM), a non-L-type voltage-gated Ca2+ channel (VGCC) antagonist, eliminated the dbcGMP effect. omega-conotoxin GVIA (2 microM), the N-type Ca2+ channel antagonist, or L-type Ca2+ channel antagonists (D600, 50 microM, or nifedipine, 10 microM) did not alter the dbcGMP effect. Ryanodine (10 microM) did not alter the effect of dbcGMP. Therefore, cGMP could play a part of role of an intracellular messenger in primary sensory neurons of the autonomic nervous system.