Modulation of renal noradrenaline release by prejunctional receptor systems in vitro.

1. The amount of noradrenaline released per nerve impulse from renal sympathetic nerves can be modulated through specific prejunctional receptors. 2. Under in vitro conditions activation of alpha 1-, alpha 2-, prostaglandin, adenosine, dopamine and serotonin receptors inhibits noradrenaline release from the kidney. 3. Stimulation of prejunctional beta-adrenoceptors, probably of the beta 2-subtype, as well as stimulation of prejunctional angiotensin II receptors facilitates noradrenaline release. Moreover, neuronally released noradrenaline inhibits its own release through activation of both prejunctional alpha 1- and alpha 2-adrenoceptors. 4. Locally produced PGE2, which is formed and released via stimulation of postjunctional alpha 1-adrenoceptors, as well as adenosine, released from postjunctional sites by renal nerve stimulation (RNS), seems to inhibit noradrenaline release through their specific prejunctional receptor systems.