Korner Pi

The effects of changes in physical activity on major cardiovascular risk factors, hemodynamics, sympathetic function, and glucose utilization in man: a controlled study of four levels of activity.

The effects of four levels of activity on heart rate, blood pressure, cardiac index, total peripheral resistance index (TPRI), norepinephrine (NE) spillover rate, insulin sensitivity, and levels of lipids and some hormones were studied in 12 normal subjects. The randomized periods were (1) 4 weeks of below-sedentary activity, (2) 4 weeks of sedentary activity, (3) 4 weeks of 40 min of bicycling three times per week, and (4) 4 weeks of similar bicycling seven times per week. Exercise three times per week reduced resting blood pressure by 10/7 mm Hg (p less than .01) and it was reduced by 12/7 mm Hg after exercise seven times per week (both p less than .01). This was associated with reduction in TPRI, an increase in cardiac index, and cardiac slowing. At the highest level of activity, NE spillover rate, an index of sympathetic activity, fell to 35% of the sedentary value (p less than .001) in eight of 10 subjects. In two other subjects NE spillover rate rose, although blood pressure and TPRI were reduced. Metabolic changes included lowering of total cholesterol, but high-density lipoprotein level was unchanged. Insulin sensitivity rose by 27% after exercise three times per week, but declined to sedentary levels with seven times per week exercise. Maximum oxygen uptake increased linearly with activity. Exercise performed three times per week lowers blood pressure and should reduce cardiovascular risk. The same exercise seven times per week enhances physical performance with little further reduction in cardiovascular risk factors. Exercise is potentially a major nonpharmacologic method of lowering blood pressure.

EFFECT OF CHANGING LEVELS OF PHYSICAL ACTIVITY ON BLOOD-PRESSURE AND HAEMODYNAMICS IN ESSENTIAL HYPERTENSION

The long-term effect of exercise on blood-pressure (BP) was assessed in 13 untreated patients with essential hypertension. After a 6-week run-in period the levels of activity studied were sedentary, 45 min bicycling at 60-70% of maximum work capacity (Wmax) three times per week (3/week), and 45 min bicycling seven times per week (7/week), each for 4 weeks. The order differed between subjects in accordance with a Latin square. Supine BP, 48 h after each phase, averaged 148/99 mm Hg in the run-in and 143/96 mm Hg in the sedentary phase; it fell below values in the sedentary phase by 11/9 mm Hg with 3/week exercise, and by 16/11 mm Hg with 7/week exercise (both p less than 0.01). With increasing activity total peripheral resistance fell and the cardiac index rose. Plasma noradrenaline concentration fell below values in the sedentary phase by 21% and 33% after 3/week and 7/week exercise. Bodyweight and 24 h sodium excretion remained constant. Moderate regular exercise lowers BP and seems to be an important non-pharmacological method of treating hypertension.

Norepinephrine kinetics in essential hypertension. Defective neuronal uptake of norepinephrine in some patients.

SUMMARY To assess sympathetic nervous system function in essential hypertension, we measured tbe rates of release to and removal from plasma of the sympathetic neurorransmltter, norepinephrine. In normal subjects, disappearance of tritiated /-norepinephrlne from plasma, after infusion to steady state, was biexponential, with

Hydrocortisone-induced hypertension in humans: pressor responsiveness and sympathetic function.

= 2.0 ± 0.4 minutes (mean ± standard deviation) and

Sympathoadrenal system is critical for structural changes in genetic hypertension.

= 33 ± 15 minutes. Tbe rapid component of removal seemed to represent neuronal uptake of norepinephrine: the

Timolol pharmacokinetics and effects on heart rate and blood pressure after acute and chronic administration

was lengthened by the selective inhibitor of neuronal norepinephrine uptake, desipramine; it was not changed by the extraneuronal uptake blocker, cortlsol; and it was prolonged in patients with peripheral sympathetic nerve dysfunction (idiopathic autonoroic insufficiency). In eight of 37 hypertensive patients, tbe