Calcium released from intracellular stores is critical for controlling cellular processes such as secretion, synaptic transmission, and gene expression. Ryanodine receptors (RyRs) are Ca2+-permeable channels found in the endoplasmic reticulum. Currently, the relationship between Ca2+-induced Ca2+release (CICR) via RyRs and Ca2+-dependent synaptic transmission is unclear. Here, we investigated the role and potential mechanisms of RyR-mediated Ca2+ release at excitatory synapses. Experiments were performed on mouse hippocampal autaptic neurons (hANs) and adrenal chromaffin cells (CCs). The analysis of single, paired and high-frequency trains of evoked excitatory postsynaptic currents (eEPSCs) were performed to evaluate synaptic transmission. RyRs inhibition by dantrolene (10 µM) application had no effect on the amplitude of single eEPSCs, while significantly reduced the paired-pulse ratio at 25 and 50 ms inter stimulus intervals, suggesting lower probability of glutamate release. We also found that RyRs inhibition reduced the amplitude of eEPSCs during high-frequency stimulation without affecting the size of the readily releasable pool. When looking at non-L type Ca2+ channels function on CCs, a useful model for studying presynaptic mechanisms of vesicle release, we found that dantrolene application increased the mean peak amplitude of non-L type currents by approximately 50%, shifted the voltage-dependent activation to more positive potentials (~ +4 mV) and decreased by ~10% the Ca2+-dependent inactivation of non-L-type Ca2+ channels. In summary, our findings indicate that RyRs up-regulate glutamate release during high-frequency stimulation of hippocampal neurons, while in CCs prevents excessive intracellular Ca2+ accumulation by increasing the Ca2+-dependent inactivation of non-L-type Ca2+ channels.