Plasma catecholamines in Nigerians with primary hypertension.

Background: Hypertension is the most common cardiovascular disease worldwide and is a major cause of morbidity and mortality. Increased adrenergic activity is thought to play a major role in the initiation and progression of the hypertensive state. Hypertension is more severe in Blacks when compared with White patients. Much of the evidence for the increased adrenergic activity is from studies in predominantly White participants. This study aims to evaluate the adrenergic system in Black Nigerian hypertensives by measuring their plasma catecholamines.

Methods: Eighty-two newly diagnosed hypertensives and 51 normal controls were recruited for the study. Blood was obtained from the participants after an overnight fast. Also, a 24-hr urine collection was obtained. Levels of plasma noradrenaline, adrenaline, renin, angiotensin converting enzyme (ACE), atrial natriuretic peptide (ANP), aldosterone and insulin levels were determined using HPLC. Fasting plasma glucose was also determined.

Results: Plasma noradrenaline level was higher while plasma adrenaline level was lower in the hypertensives. The hypertensives also had lower levels of plasma renin, ACE, and ANP. Systolic blood pressure negatively correlated with plasma adrenaline (r = -0.29, P < .001) and positively correlated with plasma noradrenaline (r = 0.31, P < .001). Renin and ANP also correlated negatively with blood pressure (r = -0.22, P = .012 and r = -0.34, P < .0001 respectively).

Conclusions: Black Nigerian hypertensives demonstrate elevated levels of plasma noradrenaline when compared with normal controls. This is consistent with the hypothesis of the hyperadrenergic state in hypertension. Further studies are needed to relate the hyperadrenergic state to the racial differences in the severity of hypertension.