The relevance of baroreflex mechanisms to the control of ambulatory and exercise blood pressure in humans.

1. The article reviews the phenylephrine 'ramp' method for studying the baroreceptor-heart rate reflex and the method of power spectral analysis for studying variability of blood pressure and of the R-R interval. 2. These methods have been used to study changes in reflex properties during arousal from sleep, changes which occur acutely after physical exercise and with training, changes in hypertension, and after myocardial infarction. 3. Several of the above changes are attributable to altered properties of the arterial baroreceptors, but some involve changes in central nervous information processing.