Interaction of peripheral and central respiratory drives in cats. I. Effects of sodium cyanide as a peripheral chemoreceptor stimulus at different levels of CSF pH.

In cats anesthetized with chloralose-urethane, the central respiratory chemoreceptors were exposed to mock CSF of pH 7.02, 7.02, or 7.57. The right carotid body was simultaneously stimulated by intracarotid injections of 40, 80, or 160 microgram sodium cyanide in 200 microliter Ringer solution. The left carotid nerve and, in some animals, both vagosympathetic truncs were dissected. It could be demonstrated that the increase in ventilation produced by application of NaCN to the peripheral chemoreceptors is significantly larger at high than at low mock CSF pH (i.e. at low than at high central stimulus intensity). In vagotomized cats the responses of VT and V to NaCN similarly depend upon CSF pH; they are somewhat larger, though, than in intact animals. These results are discussed as compared with results reported by different authors.