Cerebral Blood Flow Velocity During A Short Period Of Carotid Baroreflex Stimulation In The Young And Middle-Aged Humans

Abstract

Objective: Cerebral blood flow velocity (CBFV) concomitant with the acute response and resetting of baroreflex has not yet been studied. The present study addresses this in the young and the middle-aged human beings. Materials and Methods: Four groups of healthy volunteers were included into the study (13 members in each): young males (23.9±0.8 yrs), young females (24.2±0.7 yrs), middle-aged males (58±0.9 yrs) and middle-aged females (56.4±0.7 yrs). Transcranial Doppler ultrasonography and Eckberg's neck suction device were used for CBFV monitoring and carotid baroreceptors stimulation respectively. Pressure in the neck chamber was reduced immediately to -40 mmHg which lasted for 30 sec. CBFV and electrocardiograph were monitored before, during, and after the baroreceptors stimulation. Results: In all the groups, baroreflex stimulation led to a significant increase in R-R intervals and was then followed by a gradual resetting. CBFV did not change during acute phase of the baroreflex stimulation, but it was reduced simultaneous to the resetting phase which reached to the significant levels in young females and middle-aged males (p<0.05). Conclusions: Our findings support the existence of an effective local maintenance of CBFV during acute response of the carotid baroreflex in both young and middle-aged groups. However during the rapid resetting phase of the reflex it decreased in both age groups of the study. THIS RESEARCH WAS DONE IN Departments of Physiology and Neurology, Neurodiagnostic Ward, Doppler unit, Imam Medical Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.