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

The effect of dibutyryl cGMP (dbcGMP), a membrane permeant cCMP analogue, o n cytosolic concentrations of Ca2+ ([Ca2+](i)) was studied in cultured nodo se ganglion neurons of the rabbit using fura-2AM and microfluorometry. Appl ication of dbcGMP (10-1000 mu M) increased [Ca2+](i) in 42% of neurons (n = 67). The effect was observed in a dose-dependent fashion. The threshold do se was 100 mu M and the increase at 500 mu M averaged 117 +/- 8%. Removal o f extracellular Ca2+ abolished the dbcGMP effect. Application of Ni2+ (1 mM ) or neomycin(50 mu M), a non-L-type voltage-gated Ca2+ channel(VGCC) antag onist, eliminated the dbcGMP effect. omega-conotoxin GVIA (2 mu M), the N-t ype Ca2+ channel antagonist, or L-type Ca2+ channel antagonists (D600, 50 m u M, or nifedipine, 10 mu M) did not alter the dbcGMP effect. Ryanodine (10 mu M) did not alter the effect of dbcGMP. Therefore, cGMP could play a par t of role of an intracellular messenger in primary sensory neurons of the a utonomic nervous system. (C) 1998 Elsevier Science B.V. All rights reserved .