Artificial perfusion of the ponto-medullary region of cats. A method for separation of central and peripheral effects of chemical stimulation of ventilation.

A technique is described by which the ponto-medullary region of anaesthetized cats is artificially perfused with their own blood in which the blood gas tensions are varied independently from gas exchange in the lung. Blood from a femoral artery is fed into a foamer and defoamer. After alteration of the blood gas tensions in this equilibrator it is pumped via a cannulated vertebral artery into the medulla oblongata, pons and cerebellum. In this way two separately perfused areas are obtained in which the blood gas tensions can be changed independently. The peripheral chemoreceptors are supplied with blood of the systemic circulation while the central chemoreceptors and respiratory integrating centres are artificially perfused. With this technique the contribution of the peripheral and central chemoreceptors to the total ventilation and their interaction can be assessed. In addition the method is also suitable for studying the effects of drugs on the central regulation of respiration and circulation.