Responses of single-unit carotid body chemoreceptors in adult rats

1.Our goal was to describe the in situ responses in rats of single-unit carotid body chemoreceptors to changes in arterial P-O2 and P-CO2. We identified single-unit carotid chemoreceptor activity in male, adult Sprague-Dawley rats by their rapid responses to I.V. NaCN (20 mug) and transient (10 s) asphyxia. 2. Single-unit chemoreceptor responses to isocapnic changes in oxygenation within the arterial oxygen pressure range 34-114 mmHg were described by the power function: f(dis) = 74010(P-a,P-O2)(-2.5); (r(2) = 0.6), where f(dis) is the discharge frequency (spikes s-(1)), P-a,P-O2 is the arterial oxygen partial pressure (mmHg) and r2 is the correlation coefficient. 3. The responses to iso-oxic changes in CO2, assumed to be linear, had a slope of 0.089 spikes s(-1) (mmHg P-a,P-CO2)(-1)(r(2) = 0.7). 4. We conclude that carotid body chemoreceptors in adult rats have responses to changes in P-a,P-O2 and P-a,P-CO2 similar to those of other species.