Increased noradrenaline release in rat portal vein during sympathetic nerve stimulation due to activation of presynaptic beta-adrenoceptors by noradrenaline and adrenaline

• Published in: European journal of pharmacology Vol. 50; no. 1; p. 75
• Main Authors: Dahlöf, C, Ljung, B, Ablad, B
• Format: Journal Article
• Language: English
• Published: Netherlands 01-07-1978
• Subjects: Animals; Blood Vessels - metabolism; Desipramine - pharmacology; Epinephrine - pharmacology; In Vitro Techniques; Norepinephrine - metabolism; Norepinephrine - pharmacology; Normetanephrine - pharmacology; Phenoxybenzamine - pharmacology; Portal Vein - metabolism; Propranolol - pharmacology; Rats; Receptors, Adrenergic - drug effects; Receptors, Adrenergic, beta - drug effects; Stimulation, Chemical
• ISSN: 0014-2999
• DOI: 10.1016/0014-2999(78)90255-8

With the aim of investigating whether exogenous noradrenaline (NA) and adrenaline (A) can modulate transmitter release via the stimulation of presynaptic beta-adrenoceptors, 3H-release from isolated portal veins was studied after pretreatment with 3H-1-NA, phenoxybenzamine, desipramine and normetanephrine. NA (10 muM) and A (0.05 muM) increased the fractional 3H-release elicited by sympathetic nerve stimulation by 30%. This effect could be blocked by d, 1-propranolol which per se reduced the release by 10%. It is concluded that NA can facilitate its own release via a presynaptic beta-adrenoceptor-mediated positive feed-back mechanism and that adrenaline can stimulate this beta-adrenoceptor-mediated mechanism.