The Effect of Nerve Stimulation on the Uptake of Noradrenaline into the Adrenergic Nerve Terminals

In rats pretreated with reserpine and nialamide the effect of sympathetic stimulation, 20 and 6 imp/sec, on the uptake of exogenous noradrenaline was studied in the adrenergic nerves of the iris and salivary glands using fluorescence and biochemical methods, respectively. The uptake of noradrenaline was smaller on the stimulated than on the unstimulated side. The results are discussed with respect to factors such as changes in the circulation, transmitter release during the stimulation, and the presence of an intermittent blockade of the membrane pump during the impulses. It is suggested that the latter mechanisms might be of some physiological importance.