Role of histamine and histaminergic agents on noradrenaline uptake in smooth muscle preparations.

It has been shown that adrenergic neurotransmission in different tissues can be modified by histamine (HIST) but the mechanisms of this action have still not been fully clarified. This study aimed to demonstrate the possible involvement of H-receptor subtypes in the realization of histamine inhibitory effects on smooth muscle tissues. HIST, 2-(2-aminoethyl)thiazole (AET) and dimaprit (DMP) exerted a similar inhibition of noradrenaline (NA)-uptake1 in rat vas deferens and rabbit ear artery. After H1-blockade with mepyramine (MEP), HIST and DMP did not change the uptake1 in rat vas deferens and decreased NA neuronal accumulation in rabbit ear artery. The H2-blockade with ranitidine (RAN) did not affect HIST- and AET-induced inhibition of NA-uptake1 in rat vas deferens and completely abolished it in rabbit ear artery. These data suggest that different H-receptor subtypes might be involved in HIST inhibitory action on NA neuronal uptake in both tissues. It appears, however, that the inhibition of NA uptake1 plays only a minor role in the effects of HIST on smooth muscle contractions.