Introductory remarks: oxygen linked response of carotid chemoreceptors.

Abstract

Recognition of oxygen in the animal organism is a fundamental phenomenon in biology. There are various examples of physiologic responses to small changes in oxygen pressure in the range of normal PO2 at sea level. We have already had glimpses of these chemoreception functions in the previous sessions of the symposium. In mammals the outstanding examples are provided by the microscopic organs along the aortic and carotid arteries known as peripheral arterial chemoreceptors. Their oxygen reception function is well seen in the stimulation of breathing due to hypoxia. It is well known that a decrease in arterial PO2 results in an increase in breathing if the nervous connections of the receptors with central nervous system are intact. This is shown in figure 1. After denervation of these receptors a similar intensity of hypoxia results in decreases of ventilation. Thus decreases in alveolar and arterial PO2 show simultaneous dual effects on ventilation: the net effect in intact animal being stimulation of ventilation. Regardless of the mechanisms involved these results clearly demonstrate oxygen sensitive property in more than one system.