Figure 10. Physiological properties of two type VI neurones.

Aa and Ab, increased neuronal discharge in response to elevation of mean arterial blood pressure (MAP) by aortic occlusion (AOc) and cardiopulmonary receptor stimulation with phenylbiguanide (PBG, 10 μg kg⁻¹, i.v.). Reduction of AP abolishes the neuronal discharge. In Ab, each pair of traces (unit activity at top, AP at bottom) represents an excerpt of the raw data used for panel Aa. The peak to peak amplitude of spikes is 1.2 mV, the top and middle pairs of traces each have a total duration of 28 s, and the bottom pair (SNP) has a total duration of 75 s. Ba, increased neuronal discharge in response to elevation of MAP. This cell did not react to PBG injection but it stopped firing after the injection when systemic blood pressure dropped. Bb, neuronal discharge is directly proportional to MAP beyond a threshold. Bc, pulse-synchronous discharge of type VI neurone.