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 (SEP) 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: SEP (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 (SEP: P=0.001, diastolic blood preasure (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.