Figure 1.

(a) An illustration of the techniques used to obtain a representative value of RHDN in Trial 2. Zero on the ordinate was defined by the lowest diastolic minimum, and the overall amplitude of the wave as the distance from this zero to the lowest systolic maximum. The notch height was defined as the distance from the zero to the mid-point between the lowest and the highest notches (notches being defined by the change in gradient in the post-systolic falloff). RHDN was calculated as notch height divided by overall amplitude (0.41 in this case). (b) A recording showing the multiple peaks which can occur after prolonged infusion with L-NAME. In both (a) and (b), the distance between vertical grid lines corresponds to 1 s.