Adrenaline and the development of genetic hypertension

The effects, on the development of a raised blood pressure in spontaneously hypertensive (SHR) rats, of bilateral adrenal demedullation and subcutaneous slow-release implants containing adrenaline, salbutamol and procaterol were studied. Systolic blood pressure (SBP) measurements were made, using an indirect tail-cuff method in groups of male SHR rats aged from three to 14 weeks, which were sham-operated or bilaterally adrenal demedullated under ether anaesthesia at four weeks of age. Bilateral adrenal demedullation attenuated the development of a raised blood pressure, while slow-release implants of adrenaline restored the development of hypertension in adrenal demedullated rats and this effect was abolished by concomitant treatment with the beta 2-adrenoceptor antagonist [C] 118551. Implants of salbutamol and procaterol were also effective in restoring hypertension development in adrenal demedullated rats. It is suggested that adrenaline exerts its pro-hypertensive effects via an action at beta 2-adrenoceptors; possibly those located prejunctionally which are involved in the facilitation of sympathetic neurotransmission.