Uptake and re-use of sympathetic transmitter in the cat’s spleen

Abstract

The output of transmitter resulting from stimulation of the sympathetic nerves of the cat’s spleen, perfused with homologous blood, is described and compared with similar results obtained from the spleen in situ. Transmitter overflows are somewhat lower in the spleen perfused by the present method, but the relationship between overflow and frequency of stimulation is the same as in the spleen in situ. Noradrenaline added to the perfusate at rates as high as 6 μg/min is taken up by the spleen which shows no sign of saturation even at these high levels of presentation. Loss of transmitter from the spleen causes a progressive decline in the overflow of transmitter produced by successive trains of stimuli. Evidence is presented to support the hypothesis that the continued effectiveness of a sympathetic nerve depends upon the uptake and re-use of the transmitter that it liberates.