Possible impairment of the sympathetic nervous system response to postprandial hypotension in elderly hypertensive patients.

In a randomised, single-blind, cross-over study, the effects of a high carbohydrate meal or 'no meal' on BP, pulse rate, blood glucose, plasma insulin and catecholamine levels were assessed in eight fit, untreated, elderly hypertensive subjects. A significantly greater fall in supine (P = 0.006) and erect (P = 0.03) systolic blood pressure (SBP) occurred post-meal compared with the no meal phase. The maximum postprandial fall in supine SBP (-24 mmHg, 95% CI -16 to -32 mmHg) occurred at 60 minutes and was associated with a significant rise in supine pulse rate. No overall difference in diastolic BP was seen between the two phases and orthostatic control of BP was maintained. Blood glucose and plasma insulin levels rose after the meal but plasma noradrenaline levels were unchanged during both phases. Thus in these elderly hypertensive subjects the postprandial fall in SBP was not associated with an overall increase in sympathetic nervous system (SNS) activity (as gauged by plasma noradrenaline levels), unlike the findings previously reported in normotensive elderly and young subjects. These changes in BP and the possible impairment of the SNS response to postprandial hypotension should be considered when assessing the BP control, particularly after therapeutic intervention, in elderly hypertensive patients.