Blood pressure, heart rate and arterial blood gas reactions to acute hypoxia in carotid body denervated spontaneously hypertensive rats

Abstract

The role of the peripheral arterial chemoreceptors in the reflex control of respiration and the cardiovascular systems was studied in spontaneously hypertensive rats (SHR). In carotid body denervated and in sham-operated control rats mean arterial blood pressure, heart rate, respiratory rate and arterial blood gases were measured under normoxic conditions and in acute normobaric hypoxia. Under normoxia the carotid body denervated SHR differ from the sham-operated ones only in significantly lowered arterial pO2 and pH and in significantly increased pCO2 values. The carotid body denervated SHR react to acute hypoxia with a significantly smaller increase in respiratory rate, a more pronounced fall in the arterial pO2 and a greater decrease in mean arterial blood pressure than the sham-operated control rats. Our results suggest that carotid body chemoreceptors in SHR are of great importance in regulating respiration but of secondary consequence regarding the reflex control of the cardiovascular system.