Neurovascular responses to mental stress in prehypertensive humans

Schwartz CE, Durocher JJ, Carter JR. Neurovascular responses to mental stress in prehypertensive humans. J Appl Physiol 110: 76-82, 2011. First published November 4, 2010; doi:10.1152/japplphysiol.00912.2010.-Neurovascular responses to mental stress have been linked to several cardiovascular diseases, including hypertension. Mean arterial pressure (MAP), muscle sympathetic nerve activity (MSNA), and forearm vascular responses to mental stress are well documented in normotensive (NT) subjects, but responses in prehypertensive (PHT) subjects remain unclear. We tested the hypothesis that PHT would elicit a more dramatic increase of MAP during mental stress via augmented MSNA and blunted forearm vascular conductance (FVC). We examined 17 PHT (systolic 120-139 and/or diastolic 80-89 mmHg; 22 +/- 1 yr) and 18 NT (systolic < 120 and diastolic < 80 mmHg; 23 +/- 2 yr) subjects. Heart rate, MAP, MSNA, FVC, and calf vascular conductance were measured during 5 min of baseline and 5 min of mental stress (mental arithmetic). Mental stress increased MAP and FVC in both groups, but the increases in MAP were augmented (Delta 10 +/- 1 vs. Delta 14 +/- 1 mmHg; P < 0.05), and the increases in FVC were blunted (Delta 95 +/- 14 vs. Delta 37 +/- 8%; P < 0.001) in PHT subjects. Mental stress elicited similar increases in MSNA (Delta 7 +/- 2 vs. Delta 6 +/- 2 bursts/min), heart rate (Delta 21 +/- 3 vs. Delta 18 +/- 3 beats/min), and calf vascular conductance (Delta 29 +/- 10 vs. Delta 19 +/- 5%) in NT and PHT subjects, respectively. In conclusion, mental stress elicits an augmented pressor response in PHT subjects. This augmentation appears to be associated with altered forearm vascular, but not MSNA, responses to mental stress.