Peripheral ?_1 and ?_2-adrenoceptors involved in attenuating the intracere broventricular histamine-induced carotid sinus baroreceptor reflex inhibition in rats / 中国药理学通报

ABSTRACT

Aim To determine the roles of peripheral ? 1 and ? 2 -adrenoceptors (? 1-AR,? 2-AR) in inhibition of carotid sinus barore ceptor reflex(CSR) induced by intracerebroventricular injection (icv) of histami ne (HA).Methods The left and right carotid sinus regions were i solated from the systemic circulation in 22 male Sprague-Dawley rats anesthetiz ed with pentobarbital sodium.The intracarotid sinus pressure (ISP) was altered in a stepwise ma nner in vivo.ISP-mean arterial pressure (MAP) relationship curve and its ch aracteristic parameters were constructed by fitting to the logistic function wit h five parameters.The changes in CSR performance induced by icv HA and the effec ts of pretreatment with ? 1-AR or ? 2-AR selective antagonist into the per ipheral vein on the responses of CSR to HA were examined.Results icv microinjection of HA (60 ?mol?L -1 in 5 ?l) significantly shifted the ISP-MAP relationship curve upwards (P0.05).Conclusion The intracerebroventricular administration of HA results in a rapid resetting of CSR and a decrease in reflex sensitivity, and the functions of both the peripheral ? 1-AR and ? 2-AR may attenuate CSR resetting induced by icv microinjection of HA. Furthermore,the peripheral ? 1-AR might play an important role in mediating the responses of CSR to central HA.