Blood pressure during sustained inhibitory breathing in the natural environment.

Previous studies reported that breathing frequency of laboratory dogs decreased preceding the onset of an avoidance task and that this decrease was accompanied by increases in blood pressure and decreases in heart rate. Low frequency/normal tidal volume breathing has also been observed in ambulatory humans, but the cardiovascular concomitants of this inhibitory breathing pattern remain to be determined. The present study recorded blood pressure and heart rate in humans during periods of inhibitory breathing in the natural environment. Systolic and mean pressure were higher during inhibitory breathing than at other times, but no differences in diastolic pressure or heart rate were observed. Inhibitory breathing was differentially associated with the workplace and with social situations. Thus, major components of a physiological pattern that predisposes laboratory animals to sodium-sensitive experimental hypertension have now been observed to covary in ambulatory humans. Whether inhibitory breathing in the natural environment is a correlate or a cause of elevated blood pressure remains to be determined.