Specificity of H ion concentration as a carotid chemoreceptor stimulus

¹ Laboratory of Thoracic Physiology, Division of Anesthesiology, and Department of Physiology, Washington University School of Medicine, St. Louis, Missouri

The present study was designed to separate quantitatively the relative contributions of (H⁺) and Pco₂ as chemoreceptor stimuli. The integrated electrical activity from the entire Hering's nerve of the cat was measured and correlated with values of (H⁺), Pco₂, and Po₂ of arterial blood. By utilizing a combination of respiratory and metabolic acidosis or alkalosis, the effect of (H⁺) on carotid body nerve activity could be separated from that of Pco₂. Most studies were performed at high Po₂, a few against a changing hypoxic background. The results indicate: 1) the pre-eminence of (H⁺) as a chemoreceptor stimulus, CO₂ acting only by virtue of its effect in altering (H⁺); 2) the relationship between (H⁺) or Pco₂ and chemoreceptor activity is nonlinear; 3) the potentiation between hypoxia and hypercapnia at the chemoreceptor level is due primarily to interaction between low oxygen tension and increased (H⁺), independent of Pco₂. The significance of these findings to the exchange of CO₂ and of (H⁺) and (HCO₃^–) ions between the intracellular and extracellular milieu of the carotid chemoreceptor cells is discussed.

This article has been cited by other articles:

				H. E. Wood, M. Fatemian, and P. A. Robbins Respiratory: Prior sustained hypoxia attenuates interaction between hypoxia and exercise as ventilatory stimuli in humans Exp Physiol, January 1, 2007; 92(1): 273 - 286. [Abstract] [Full Text] [PDF]

				R. A. Henry, I-L. Lu, L. A. Beightol, and D. L. Eckberg Interactions between CO2 chemoreflexes and arterial baroreflexes Am J Physiol Heart Circ Physiol, June 1, 1998; 274(6): H2177 - H2187. [Abstract] [Full Text] [PDF]