Isometric exercise, promulgated as a test of autonomic function, has not been investigated in the elderly. Increasing age does not affect the cardiovascular responses to isometric exercise. Variability studies during fatiguing isometric exercise confirm that it is a valuable test of autonomic function in the elderly.
1. The effects of single oral doses of various sympatholytic drugs on the heart rate and blood pressure increases during isometric handgrip contraction were studied in six healthy subjects. 2. Bethanidine reduced both the systolic and diastolic increases in pressure. Clonidine reduced the systolic but not the diastolic increase. Oxprenolol alone or in combination with phentolamine or phenyoxybenzamine failed to influence the pressor response. 3. The increase in systemic blood pressure associated with sustained contraction of voluntary muscle appears to be relatively resistant to acute sympathetic adrenoreceptor blockade in man.
that is, there is approximately a 1 in 14 chance that the normal and hypertensive populations are not different in respect of the ouabain-sensitive sodium efflux rate constant. The 14 hypertensive patients include two with blood pressures of 110/92 and 160/90 mm Hg and their inclusion surely requires justification. If these two questionably hypertensive patients are excluded then the value for p becomes 0 05. It seems probable that had Dr Forrester and Professor Alleyne studied a larger group of patients with controls matched for age and sex they would have reached the same conclusion in black hypertensives as we did in our report in 1975. Certainly it is quite unjustified to use statistics in this way to claim that there are differences in sodium transport between the two hypertensive populations.
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