Arterial response during cold pressor test in borderline hypertension.

We observed previously that sympathetic activation produced by lower body negative pressure increases pulse-pressure amplification with little change in mean pressure. Whether the cold pressor test (CPT) might produce a similar hemodynamic pattern has been ignored. Ten subjects with borderline hypertension and ten age- and sex-matched normotensive controls were compared to investigate carotid-brachial pulse-pressure amplification (aplanation tonometry) and changes in brachial and carotid distensibility (echotracking technique) before and during CPT. The maneuver markedly increased blood pressure without a change in heart rate. Pulse-pressure amplification tended to disappear as a consequence of a higher increase in carotid than in brachial pulse pressure, due to an earlier return of wave reflections at the carotid site. CPT caused a significant decrease in carotid and brachial distensibility. Both results were more pronounced in controls than in borderline hypertensives. Thus CPT reduces pulse-pressure amplification. In humans, this change may greatly influence the calculation of arterial distensibility, although this point is usually minimized in animal experiments. Furthermore, in young subjects, sympathetic stimulus may induce different arterial responses, depending on the mechanism involved: reflex or global nonspecific stimulus.