Cardiovascular and plasma catecholamine response to static exercise in normotensive blacks and whites

• Published in: Ethnicity & health Vol. 2; no. 1-2; pp. 127 - 136
• Main Authors: Duey, William J., Bassett, David R., Walker, Ava J., Torok, Donald J., Howley, Edward T., Ely, Daniel, Pease, Mark O.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 01.03.1997
• Subjects: Adrenergic alpha-Agonists - pharmacology; Adult; African Continental Ancestry Group; Black American people; blood pressure; Blood Pressure - physiology; Cardiovascular response; Epinephrine - blood; ethnicity; European Continental Ancestry Group; Evaluation; Exercise - physiology; Hand Strength; heart rate; Heart Rate - physiology; Humans; hypertension; Injections, Intravenous; isometric exercise; Male; Men; norepinephrine; Norepinephrine - blood; phenylephrine; Phenylephrine - pharmacology; race; Reference Values; Structured exercise; Sympathetic Nervous System - physiology; Vasoconstrictor Agents - blood
• ISSN: 1355-7858; 1465-3419
• DOI: 10.1080/13557858.1997.9961821

Objectives. The objectives of the present study were (1) to evaluate the presser response to an isometric handgrip exercise in normotensive black and white males; (2) to measure plasma catecholamine levels pre- and post-exercise, as an index of sympathetic nervous system activity; and (3) to quantify the pressor response to bolus intravenous injections of phenylephrine (an α-specific agonist). Methods. Cardiovascular and catecholamine responses to an isometric handgrip exercise (3 minutes at 30% MVC) were measured in 15 normotensive blacks and whites. In another phase of the study, pressor responses to bolus injections of phenylephrine were assessed to evaluate α-adrenergic sensitivity. Results. The blood pressure in the blacks increased from 119/69 to 160/120 mm HG during isometric exercise, while in the whites it increased from 118/67 to 153/110 mm HG. The blacks exhibited a greater diastolic blood pressure reactivity, as evidenced by a significant race × time interaction (p < 0.05). The heart rate responses were not significantly different between the two groups. The plasma levels of norepinephrine were similar at rest, but were 25% lower in the blacks than in the whites following isometric exercise (p < 0.01). Black subjects also demonstrated an increased pressor response to intravenous injections of phenylephrine at rest (p<0.05). Conclusions. The enhanced vascular sensitivity to norepinephrine may have contributed to the greater exercise pressor response in the blacks.