Fig. 2.

An example of cardiopulmonary chemoreflex responses in mean arterial pressure (MAP), heart rate (HR), renal (RSNA), and adrenal (ASNA) sympathetic nerve activity evoked by intra-atrial injections of phenylbiguanide (2, 4, and 8 μg/kg) under control conditions (left), during hypotensive stage of severe hemorrhage (HMG; middle), and during hemorrhage evoked after bilateral blockade of adenosine receptors in the NTS (A₁ + A_2a X − HMG; right). Insets: enlarged responses evoked by injection of 8 μg of phenylbiguanide; the areas below baseline levels represent integers of the responses (measured over 30 s). Severe hemorrhage markedly attenuated hemodynamic and sympathetic responses, and the blockade of NTS adenosine receptors removed this attenuation.