[Changes produced by age in cardiovascular reflex responses].

The influence of age on reflex cardiovascular responses, elicited by orthostatic change and Valsalva's maneuver was studied in 105 healthy volunteers, and the response to cold pressor test in 87 healthy adults. The age range of the subjects was 12 to 79 years old; they were stratified by decades for statistical analysis. Included in this study were only subjects without diseases, as evidenced by anamnesis, physical examination, blood pressure recording, ECG tracings, chest X-Ray and routine laboratory tests. None of subjects showed obesity, the body mass index was between 19.6 +/- 0.9 Kg/m2 in the 10-19 year old group and 25.2 +/- 1.2 Kg/m2 in the 50-59 year old group (mean +/- SE). Systolic and diastolic blood pressure (SBP, DBP) were between 113.6 +/- 4.2 and 64.2 +/- 2.9 mmHg respectively in the 10-19 years old group and 139.8 +/- 5.0 mmHg and 79.5 +/- 3.2 mmHg respectively in the 70-79 years old group (mean +/- SE). Heart rate in supine position varied between 71.2 +/- 3.2 beats/min in the 10-19 years group and 75.8 +/- 3.0 beats/min in the 70-79 years old group (mean +/- SE). Orthostatic response. Change from supine to standing position increased mean arterial pressure (MAP) by 10.0 +/- 1.25 mmHg in the 10-19 years old group; a similar increase occurred up to 40-49 years old group; from that age on, the response became bimodal, the percentage of subjects showing a MAP decrease upon standing, increased from 20% in the 50-59 years old group to 48% in the 70-79 years old group; MAP descents ranged between -5.3 +/- 0.63 and -12.6 +/- 1.37 mmHg (mean +/- SE) and were non symptomatic. The same bimodal pattern of responses was observed in the heart rate. Cold pressor test. In the 10-19 years old group the cold pressor test induced an increase of SBP and DBP of 17.6 +/- 5.0 mmHg and 11.5 +/- 3.5 mmHg (mean +/- SE) respectively, this response remained unchanged up to 40-49 years old age. After 50-59 years old this SBP and DBP increase was reduced by 50% and 63% in the 60-69 and 70-79 years old groups respectively. Return of SBP and DBP to cold prestimulation levels was normal in all studied groups.(ABSTRACT TRUNCATED AT 400 WORDS)