Hypertension through adrenaline activation of prejunctional beta-adrenoceptors

1. Adrenaline can enhance the stimulation-induced release of transmitter noradrenaline in sympathetically innervated tissues by activating prejunctional beta-adrenoceptors. 2. Adrenaline incorporated into sympathetic transmitter stores by neuronal uptake can be subsequently released as a co-transmitter and can then activate prejunctional beta-adrenoceptors, thus completing a facilitatory feedback loop. 3. Rats chronically treated with adrenaline develop elevated blood pressures compared to control rats. beta-Adrenoceptor blockade prevents the rise in blood pressure. 4. Activation by adrenaline of facilitatory prejunctional beta-adrenoceptors of sympathetic nerves innervating cardiovascular effector tissues may explain adrenaline-induced rises in blood pressure.