Stimulus-Specific Patterns of Cardiovascular Reactivity in Type A and B Subjects: Evidence for Enhanced Vagal Reactivity in Type B

Authors


  • Drs. Muranaka and Suzuki are currently on the faculty of the Department of Psychosomatic Medicine, Tohoku University School of Medicine, Sendai, Japan. This research was supported by a NHLBI research grant, RO1 HL-22740 awarded to Dr. Williams.

Address requests for reprints to: Redford B. Williams, Jr. M.D., Department of Psychiatry, P.O. Box 3926, Duke University Medical Center, Durham, NC 27710

ABSTRACT

Recent evidence suggests that the differences in cardiovascular reactivity between individuals exhibiting the Type A behavior pattern and those that do not are not limited to excessive betaadrenergic reactivity in Type A's. Research also suggests the possibility of a tendency for enhanced alpha-adrenergically and vagally mediated cardiovascular reactivity in Type B's. In the present study, Type A and Type B subjects were exposed to stressor stimuli known to elicit either betaadrenergic or alpha-adrenergic and vagal responses in the cardiovascular system. Heart rate, blood pressure, and forearm blood flow and vascular resistance responses were measured. The two Types did not differ in response to the beta-adrenergic stimulus (mental arithmetic). However, the alpha-adrenergic/vagal stimulus (cold face stimulus) produced more prolonged heart rate and blood flow responses in Type B subjects. Results suggest that Type B's show hyperreactivity (compared to Type A) when alpha-adrenergic or vagal cardiovascular responses are elicited. The nature of this hyperreactivity suggests possible mechanisms for reduced cardiovascular disease risk in Type B individuals.

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