Possible Interaction: Guanidines and Norepinephrine

“In the vena cava, the guanidine 1,3‐di(2‐tolyl)guanidine (DTG) inhibited the electrically evoked [3H]noradrenaline release; the inhibitory effect was more pronounced in the presence than in the absence of the α2‐adrenoceptor antagonist rauwolscine.”

“1 Guanidine increased noradrenaline (NA) output at 5 Hz by 3 to 6 fold, and doubled it at 30 Hz.”

“8 It is suggested that guanidine enhances NA release partly by increasing the influx of calcium into the neurone during an action potential, and also by interfering with intracellular binding of calcium.”

“9 The ability of these guanidines to impair the release of noradrenaline by nerve impulses could occur because whilst they are present within the neurone the ‘nerve‐releasable store’, which may in these experiments appear in the supernatant fraction after homogenization, may be unable to refill with transmitter.”