Relationship of age and calcitonin gene-related peptide to postprandial hypotension

Falls following a meal occur commonly in older persons. These falls have been related to a decrease in postprandial blood pressure due to carbohydrates in the meal. The mechanism by which this occurs is not known. In this study, we examined the possible role of a vasodilatory peptide, calcitonin gene-related peptide (CGRP), which is released following carbohydrate loading in the pathophysiology of postprandial hypotension. Levels were assessed in 29 community-dwelling individuals aged 20-83 years during an oral glucose tolerance test, and heart rate and blood pressure were measured. Five subjects exhibited a postprandial reduction in systolic blood pressure (SBP) greater than 15 mmHg (mean reduction -30 +/- 4 mmHg). Four were aged over 60 (40% of the individuals in that group) and one was middle aged (11%). One individual in the older group was temporarily symptomatic, complaining of light-headedness. Linear regression analysis showed a significant association between the changes in CGRP and in blood pressure: SBP (r = 0.39, P = 0.037), and mean blood pressure (MBP) (r = 0.356, P = 0.06) in the oldest group. Individuals in this group with a greater than 15 mmHg drop in blood pressure, exhibited significantly greater changes in CGRP (SBP: P = 0.001, diastolic blood pressure (DBP): P = 0.05, MBP: P = 0.006). This association of log CGRP delta and BP change was not present in young or middle aged individuals. Thus, increases in CGRP levels were associated with blood pressure reduction, with older individuals more susceptible to these changes than younger individuals. CGRP may play a role in the pathogenesis of postprandial hypotension.