Time delays in the human baroreceptor reflex.
In 11 normotensive subjects with coronary artery disease, low intensity electrical stimulation of the carotid sinus nerves (CSN) was triggered by the R-wave in the electrocardiogram with an adjustable delay. The latent period was estimated between the start of CSN stimulation and the onset of the reflex-PP-interval prolongation and, during right atrial pacing, the onset of the reflex fall of diastolic arterial pressure and prolongation of the AV-interval. The latency to the reverse changes was determined after switching CSN stimulation off. The PP-interval changes started after a latency of 0.5-0.6 s. This latency was independent of the respiratory phase and it was independent of the directional change of the afferent activity. AV-interval changes started after about 1 s. When heart rate was fixed, arterial pressure changes started after 2-3 s. It is estimated that central processing of baroreceptor afferent activity may require 0.25 s in the human.
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D002346:Carotid Sinus / Q000294:innervation* / Q000502:physiology; D003327:Coronary Disease / Q000503:physiopathology; D004558:Electric Stimulation; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D011311:Pressoreceptors / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D013997:Time Factors