The heart rate after inhibition of nitric oxide release in the anaesthetized dog

Abstract

1. 1. The effect of nitric oxide (NO) inhibition on heart rate was studied in anaesthetized vagotomized dogs. 2. 2. The effect of changes of baroreceptor stimulation was prevented using an arterial pressure reservoir. 3. 3. After NO-inhibitor (Nitro- l-arginine), heart rate decreased by 8% in spite of an unchanged pressure. 4. 4. When upstream pressure was increased by constriction of the descending aorta, heart rate decreased by 4% before and after inhibition. Owing to the vagotomy this decrease was attributed to a sympathetic tone reduction following baroreceptor stimulation. 5. 5. The results show that NO-inhibition reduces heart rate independently of an increased baroreceptor stimulation and does not reduce the basal sympathetic control on the sinus-atrial node.