[Analysis of the dynamic action of vasoactive substances on the blood pressure of rabbits (author's transl)].

Rabbits were anesthetized with Urethane. The arterial blood pressure was recorded from the femoral artery with a Statham P 23 dB transducer. A servo-controlled Harvard Apparatus piston pump was used to infuse Acetylcholine and Noradrenaline respectively. The infusion rate was varied sinusoidally from 0.001 HZ to 0.1 HZ. The procedure was performed with different mean infusion rates and different infusion amplitudes. The response of the arterial blood pressure to the drug was examined by using the Bode analysis. The goal of our study was to examine if the blood pressure response to the infusion of a vasoactive drug can be characterized by a frequency dependent dose-response relationship. We could show that in terms of the frequency dependence the response to Noradrenaline differs in a quite typical way from the response to Acetylcholine. For both substances we were able to determine a frequency dependent transfer function. In addition we could describe the nonlinearity of the dose-dependent response of the blood pressure separately by an equation derived from the law of mass action. From the Bode diagrams the equations of the transfer functions are derived. In order to test the precision of the method, these equations were used to reconstruct the transfer function. This test is especially sensitive with respect to the phase of the function. We found a quite good agreement between calculated and measured values. This is a proof for the suitability of the method.