Inhibition of cyclooxygenase attenuates baroreceptor function and increases the pressor response to norepinephrine in man.

The possible influence of prostaglandins on baroreceptor function in man has been investigated. Baroreceptor reflex was activated by intravenous infusion of norepinephrine and the pressor response was measured, both before and after administration of indomethacin. Resting blood pressure remained unchanged after indomethacin while resting heart rate was significantly decreased as compared to placebo and the norepinephrine-induced rise in mean arterial blood pressure was significantly more pronounced. The baroreceptor-mediated decrease in heart rate tended to be smaller. Baroreceptor sensitivity (delta heart rate/delta blood pressure) was significantly reduced by indomethacin to about half of the control value. In addition to attenuation of sensitivity, the findings represent resetting of the baroreceptor setpoint and a more pronounced pressor response to norepinephrine after cyclooxygenase inhibition. Thus, eicosanoids originating via the cyclooxygenase pathway of arachidonate metabolism may modulate the vascular response to adrenergic stimulation and may participate in the regulation of baroreceptor reflex setpoint and sensitivity.