Arterial compliance may influence baroreflex function in athletes and hypertensives.
The present study investigated arterial compliance as a possible influence on mean arterial pressure-heart rate (MAP-HR) reflex function in athletes and hypertensives. Aortic stiffness and systemic arterial compliance (SAC) were estimated in 25 elite male athletes and 25 age-matched sedentary controls. Blood pressure did not vary between groups, but SAC was higher in the athletic compared with the sedentary group (0.46 +/- 0.04 vs. 0.37 +/- 0.02 arbitrary compliance units; P = 0.03). In five hypertensives and six age-matched normals and in a subgroup of seven athletes and seven age-matched controls the sigmoidal MAP-HR reflex was assessed using phenylephrine and nitroprusside. In athletes compared with sedentary subjects MAP-HR reflex sensitivity was the same; however, the maximum tachycardia in response to blood pressure reduction was lower in the athletic group (87.1.1 +/- 3.7 vs. 97.1 +/- 2.9 beats/min; P = 0.05). Athletes had a higher blood pressure corresponding to 95% of the HR range (64.2 +/- 3.2 vs. 54.0 +/- 2.1 mmHg; P = 0.02), but there was no difference in the blood pressure corresponding to 5% of the HR range. The blood pressure excursion necessary to traverse the baroreceptor transducer range (MAPd) was therefore less in athletes compared with normals. The beta-index of aortic stiffness correlated closely with MAPd (R = 0.70; P < 0.01). In hypertensives reflex sensitivity was reduced, the minimum HR was elevated, and the MAPd was 56% greater compared with normals.(ABSTRACT TRUNCATED AT 250 WORDS)
Alfred and Baker Medical Unit, Baker Medical Research Institute, Prahran, Victoria, Australia.
B A
BA
Kingwell
J D
JD
Cameron
K J
KJ
Gillies
G L
GL
Jennings
A M
AM
Dart
D000328:Adult; D001158:Arteries / Q000502:physiology* / Q000503:physiopathology; D017704:Baroreflex; D001794:Blood Pressure; D003971:Diastole; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D005082:Physical Exertion; D012044:Regression Analysis; D013177:Sports; D013599:Systole