NTS A2a adenosine receptors inhibit cardiopulmonary chemoreflex of sympathetic outputs

Zeljka Minic, Donald O'Leary, Tadeusz Scislo

Background:
The nucleus of the solitary tract is known to be a primary modulator of the cardiopulmonary chemoreflex (CCR) via adenosine receptors (A1 and A2a). Unlike the rest of the CNS, the A2a is the primary receptor within the NTS compared to the A1 receptors.  Stimulation of the A2a receptors in the NTS shows regional specific changes in sympathetic nerve activity output such as decreases in RSNA or increases in pre-ASNA.  Here the question was whether stimulation of the A2a receptors in the NTS would promote region specific inhibition of the CCR.

Methods:

• Microinjections into the NTS
• Neuron recording

Results:
Although it is seen that stimulation of A2a receptor causes differential effects on SNA, it was shown in this study that stimulation of A2a receptor causes universal inhibition of CCR responses. Presenting for the first time, that A1 and A2a receptors my function synergistically to control cardiovascular reflexes through different mechanisms.

~JI