Arterial hydrogen ion versus CO2 on depth and rate of breathing in decerebrate cats.

Abstract Arterial blood hydrogen ion concentration (Ha + ) was altered over the range of 25 to 110 nM (pH 7.60 to 6.96) by slow intravenous infusion of 1.0 N NaHCO 3 or 0.5 N HCl at controlled levels of P a co 2 in unanesthetized decerebrate cats. Respiratory f varied as a single function of VT irrespective of alterations in P a co 2 and Ha even after interruption of the carotid sinus nerves. The dependence of f upon vt was abolished by vagotomy. However, V t continued to respond to changes in Ha over its entire range after combined section of the vagus and carotid sinus nerves. In all states of peripheral innervation, the ΔV t ΔHa + response to inhalation of CO 2 exceeded by 5 to 10 times the ΔV t /ΔHa + response to acid or bicarbonate infused under isocapnic control. Increases and decreases of Ha t caused downward and upward shifts. respectively, in the operating setpoint of the CO 2 regulation system.