[Pulmonary stretch receptors activity during thermal polypnea (author's transl)]

1 We have studied the unit activity of 88 pulmonary stretch receptors (RPI) in the vagus nerve of the cat by using the single fibre technique. 2 In spite of a 38% decrease in tidal volume, the discharge frequency of RPI is statistically unchanged during polypnea, However, RPI are recruited earlier, but their discharge overlaps expiration. 3 Individual influences of tidal volume, temperature, and FACO2 on RPI activities are tested. During polypnea, the excitatory influences of hyperthermia and hypocapnia act against the depressing action of tidal volume reduction: RPI are still active. 4 During polypnea, respiratory rhythm and tidal volume are unchanged after bivagotomy. RPI activity seems functionally insignificant. This result suggests that the thermally induced respiratory response is mediated by structures in the upper brain stem (probably the preoptic anterior hypothalamus) and is not dependent on the integrity of the vagus nerve.