The pharmacological nature of the response of the reserinized guinea-pig vas deferens to postganglionic nerve stimulation.

1. Intracellular recordings from single smooth muscle cells of the guinea-pig vas deferens have been made after depletion of neuronal stores of noradrenaline by chronic reserpine treatment.2. Junctional responses to postganglionic hypogastric nerve stimulation were depressed, but large excitatory junction potentials (EJPs) and action potentials could still be evoked by stimulation at 1-2 c/s.3. These junctional responses were not reduced by the presence of hyoscine (5 x 10(-7) g/ml.), but were greatly depressed by the presence of bretylium (2 x 10(-6) g/ml.).4. Even in the presence of bretylium, junctional responses leading to action potentials could still be evoked by using high voltages of stimulation.5. It is concluded that when neuronal noradrenaline stores have been depleted by reserpine some noradrenaline is still available for release by nerve stimulation.6. It is further concluded that if the non-adrenergic component of the response of the guinea-pig vas deferens to nerve stimulation is cholinergic, this component is resistant to blockade by hyoscine.