We explored the contribution of different calcium channel types to the long-term potentiation (LTP) of superior cervical ganglion of the rat. Right after a conditioning train of 40 Hz for 5 s, the maximum amplitude of the postsynaptic response (maximum potentiation) increased 5.6+/-0.5-fold. Potentiation decreased to 20% of its initial value within the following 70.0+/-8.0 min (LTP decay time). The contribution of P/Q-, N- and L-type calcium channels to LTP was studied by blocking their activity with synthetic funnel-web spider toxin (10 or 100 microM), omega-conotoxin GVIA (5 microM) or nifedipine (10 microM), respectively. The three blockers reduced the amplitude of the postsynaptic compound action potential before the conditioning train. After the train, all of the toxins reduced the LTP decay time and the integral of the amplitude versus time curve, defined as the LTP extent. In addition, all three blockers increased the maximum potentiation. Our results demonstrate that different calcium channel types contribute to ganglionic LTP. These effects may be by coupling excitation-secretion from different types of synaptic vesicles.