부산대학교 도서관

Hypertension is the leading contributor to cardiovascular disease globally. It is an underrecognized and common clinical problem among young adults (usually defined as younger than 40). Even in the young blood pressure elevation is predictive of long-term cardiovascular disease, and mortality. Despite its frequency, the underlying mechanisms driving hypertension are not fully understood. Previous studies have noted the presence of elevated sympathetic nerve activity among adults with hypertension and this has been shown to play a role in driving and sustaining the hypertensive state. Animal models of disease have suggested that the carotid body, a tiny structure sitting at the bifurcation of the common carotid artery may be responsible for this sympathetic activation, contributing to the hypertensive state. However, human studies have been less clear. This study sought to examine whether young adults with hypertension showed A) evidence of carotid body activation as measured by their ventilatory response to hypoxia at rest and during exercise and/or B) tonic activation of the carotid body evidenced by a reduction in ventilation and BP at rest and exercise with blockade of the carotid chemoreflex using dopamine. 14 hypertensive participants (mean age 27 ± 5 years, 6 female) were recruited to the study alongside 14 age and sex matched normotensive controls. Hypertension was confirmed by ambulatory blood pressure monitoring (ABPM). Participants underwent an assessment of their peripheral chemoreflex (mediated by the carotid body) using a series of hypoxic stimuli delivered by transient administration of 100% Nitrogen. The ventilatory and haemodynamic response to this was measured. This was performed during a resting state, in the presence of a dopamine and a saline infusion. This was repeated during a low intensity exercise protocol on an upright cycle ergometer. No difference in carotid body activity by these measures was seen between hypertensive and normotensive young adults.