AbstractIsolated rat vas deferens preparations were intermittently field stimulated (30 s every min) for 2 or 4 h at 7 or 25 imp/s. At the low stimulation frequency only a very small reduction (7 %) of the endogenous noradrenaline (NA) stores was seen during 4 h stimulation while it was about 15%after 2 h and 37%after 4 h at 25 imp/s. Addition of drugs known to inhibit NA synthesis (a‐methyl‐p‐tyrosine, a‐MPT, 4times10‐4M) or uptake (cocaine, 10‐5M) did not apparently influence neither the spontaneous nor *the nerve‐induced reduction of the endogenous NA stores. The present results seem to support the hypothesis that the functional transmitter pool of the short adrenergic neurons of the vas deferens is very small, and that the residual NA reuptake and synthesis after pharmacological blockade, together with minute refilling from the large storage pools, are able to maintain transmitter homeostasis without significant changes of the total endogenous NA content of the