Impact of meditation on resting and ambulatory blood pressure and heart rate in youth.

OBJECTIVE: The purpose of this study was to evaluate the impact of a meditation program on resting and ambulatory blood pressure and heart rate in youth. METHODS: Data from 73 middle school students (age 12.3 +/- 0.6 years) randomly assigned by classroom to either meditation (N = 34) or health education control (N = 39) groups were analyzed. The meditation groups engaged in 10-minute sessions at school and at home after school each day for 3 months. Resting (seated) systolic blood pressure, diastolic blood pressure, and heart rate measurements were obtained pretest and posttest on three consecutive school days using Dinamap 1846SX monitors. Ambulatory systolic blood pressure, ambulatory diastolic blood pressure, and ambulatory heart rate were recorded over 24-hour periods at pretest and posttest every 20 minutes during self-reported normal waking hours and every 30 minutes during self-reported normal sleep hours using Spacelabs 90207 monitors. RESULTS: Significant (p < .05) differences in average change from pretest to posttest were found between the meditation and health education control groups for resting systolic blood pressure (-2.7 vs. 1.1 mm Hg), daytime ambulatory systolic blood pressure after school (-2.0 vs. 3.6 mm Hg), daytime ambulatory diastolic blood pressure after school (0.1 vs. 4.3 mm Hg), and daytime ambulatory heart rate after school (-5.3 vs. 0.3 bpm). CONCLUSION: These findings demonstrate the potential beneficial impact of meditation on blood pressure and heart rate in the natural environment in healthy normotensive youth.

Elevated arterial pressure impairs autoregulation independently of AT(1) receptor activation.

OBJECTIVE: These studies determined the ability of AT1 receptor blockade or 'triple therapy', to reverse angiotensin II-induced hypertension and improve autoregulatory behavior. DESIGN: Experiments to determine if regulation of systolic blood pressure, in the normotensive range, would improve renal microvascular autoregulatory behavior in angiotensin II-infused rats. METHODS: Hypertension was induced by chronic angiotensin II infusion (60 ng/min) for 10-14 days. Two groups of angiotensin II-infused rats received either AT1 receptor blockade, with candesartan cilexetil, or triple therapy, with hydralazine, hydrochlorothiazide and reserpine, beginning on day 6 or day 0 of angiotensin II infusion, respectively. Sham animals were studied as normotensive controls. Systolic blood pressure was measured by tail cuff. Autoregulatory behavior was assessed using the juxtamedullary nephron technique in response to step (15 mmHg) increases in perfusion pressure from 65 to 170 mmHg. RESULTS: Angiotensin II infusion increased systolic blood pressure from a baseline of 125 mmHg to 162 and 182 mmHg after 10 and 14 days, respectively. Candesartan cilexetil and triple therapy normalized the blood pressure to between 119 and 126 mmHg. Increasing perfusion pressure, from 65 to 170 mmHg, reduced afferent arteriolar diameter by 30% in sham-treated kidneys. Autoregulation was significantly blunted in angiotensin II-infused rats, resulting in a pressure-mediated vasoconstriction of only 10%. Candesartan cilexetil, or triple therapy, significantly improved autoregulatory behavior, as indicated by pressure-mediated vasoconstrictor responses of 30 and 40%; respectively, despite continued angiotensin II infusion. CONCLUSIONS: These data suggest that chronic elevation of arterial blood pressure, rather than chronic AT1 receptor stimulation, is sufficient to induce hypertensive impairment of renal autoregulatory capability.