Differential effect on the sympathetic transmitter level in uterus and other organs of guinea‐pig by drugs interfering with adrenergic nerve functions

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Abstract
5 types of adrenergic blocking agents with different modes of action were administered and the rate of transmitter depletion was studied in different uterine regions of guinea‐pig, and compared with that in the heart and submandibular gland by a combination of fluorescence histochemical and spectrofluorimetric methods. The tyrosine‐hydroxylase inhibitor, H 44/68, as well as reserpine and guanethidine, produced a more efficient reduction in neuronal noradrenaline in the heart and submandibular gland than in the uterus. A differential action on the sympathetic transmitter, though less clearcut, was seen with 6‐hydroxydopamine. The noradrenaline‐depleting effect of metaraminol did not distinguish between those adrenergic nerves supplying the uterus from those of the control tissues. It is suggested that the differential effects may be related to a lower activity in the uterine adrenergic nerve system, probably because this system is to a large extent composed of short adrenergic neurons, which appear to have a particularly slow transmitter turnover.