A Study of the Mechanism of Postprandial Hypotension in Essential Hypertension

Abstract

In order to elucidate the mechanism of blood pressure control system on patients with essential hypertension (EH), postprandial changes of blood pressure (BP), pulse rate (PR), blood sugar (BS), serum insulin (IRI), plasma norepinephrine (PNE) and renin activity (PRA) were investigated in 60 patients with EH, who were divided into following two groups: 1) 37 EH patients without diabetes mellitus (HN), and 2) 23 EH patients with diabetes mellitus (HD). Twenty-four healthy volunteers (NN) and 13 normotensive diabetic patients (ND) underwent the same study as the EH patients.Systolic and diastolic blood pressure significantly decreased in all groups after ingestion of the test meal, and the postprandial decrease in BP tended to be greater in HN and in HD compaired to their normotensive control groups (NN and ND, respectively). Prolonged hypotensive response to ingestion of the test meal was observed in hypertensive groups (HN and HD). The change in BP after ingestion of the test meal appears to be affected by aging, because the decrease in BP after ingestion of the test meal in elder subjects was greater than that in younger subjects. The decrease in BP induced by the test meal was not associated with the increase in IRI in any group. The maximum increase in PNE, PRA and IRI was followed by a maximum decrease in BP. Ingestion of the test meal induced a significant increase in PNE in two normotensive groups (NN and ND) and in HN, but not in HD. A postprandial increase in PNE was associated with an increase in IRI. Postprandial change in BP was negatively correlated to the change in PNE. An increase in PRA after ingestion of the test meal was observed only in NN. The increase in PRA was accompanied by an increase in IRI.These results suggest that the splanchnic blood pooling after ingestion of the test meal may be important for the postprandial decreases in BP, and that activation of the sympathetic nervous system as well as the renin-angiotensin system, which is probably triggered by baroreceptor stimulation and an increase in circulatory insulin, may play a crucial role in recovery of postprandial decrease in BP. It is possible that an enhanced and prolonged decrease in BP observed in older patients with EH, especially those with diabetes mellitus and hypertension may be attributed to the age-related impairment of the sympathetic nervous system and the renin-angiotensin system.