Aerobic fitness level (VO2max) moderates the increased cardiovascular function and basal thromboxane formation of young healthy Type A males.

The authors evaluated the interaction between physical fitness and Type A behavior on vascular production of prostacyclin and platelet thromboxane in response to a standard vessel injury. Ninety-seven male university students were classified as Type A or B on the basis of the Structured Interview of Rosenman. Reactivity, as measured by changes in systolic blood pressure (SBP), and heart rate (HR), measured before and after a stressful Stroop task 1 week later, showed that Type A individuals were more reactive to the stressor than Type Bs, providing independent confirmation of the behavioral interview assessment procedure. Fitness level was determined by a graded treadmill test and was not different for Type As and Type Bs. Basal thromboxane production, measured as the primary metabolite, thromboxane B2, in blood oozing from the bleeding-time site, was highest among unfit Type A subjects. Fit Type As and Type Bs showed significantly lower thromboxane production. No significant differences in prostacyclin production were seen. This study marks the first time that behavior pattern has been linked to an adverse aspect of a thrombosis-related parameter likely to be involved in the genesis of cardiovascular disease. The present results also indicate that physical fitness may, in some fashion, ameliorate the "toxic" effects of Type A behavior.

The structured interview elicits a differential prostacyclin response in A and B behaviour types.

OBJECTIVE: To determine whether individuals exhibiting the type A behaviour pattern have a different extent of prostacyclin or thromboxane production after relaxation or after a structured interview compared to individuals exhibiting the type B behaviour pattern. DESIGN: Subjects were randomized to receive prospectively either a relaxation session or a mildly stressful interview first. Each then received the alternate treatment second. SETTING: Students attending an introductory psychology course at the University of Manitoba received a relaxation session (20 mins lying down listening to a tape) and an interview session (the structured interview of Rosenman). OUTCOME MEASURES: Type A/B behaviour pattern was rated using the structured interview of Rosenman. Production of 6-keto prostaglandin F1-alpha and thromboxane B2, metabolites of prostacyclin and thromboxane A2, respectively, were measured in response to a standardized vascular injury-bleeding time. MAIN RESULTS: No significant differences were observed in the length of bleeding time, in bleeding time thromboxane production or in prostacyclin production after relaxation between individuals exhibiting type A and B behaviour patterns. Prostacyclin production after the interview was lower in type A individuals (3.29 +/- 0.29 pg/min) than in individuals exhibiting type B behaviour (4.76 +/- 0.63 pg/min) (P = 0.04). No significant post interview differences in bleeding time or in thromboxane production were seen. CONCLUSION: After relaxation, type A and B subjects are similar in their prostacyclin and thromboxane responses to vascular injury. However, type A individuals show a less favorable prostacyclin response than type B when confronted with the structured interview; type A individuals responded in an aggressive or hostile fashion, while the type B individuals exhibited a more relaxed response.

The interactive effects of Type A behavior and hostility on bleeding time thromboxane and prostacyclin formation.

Sixty-six male university students were classified as Type A or B on the basis of the Structured Interview of Rosenman and as hostile or non-hostile on the basis of the Cook-Medley scale. Vascular production of prostacyclin and platelet thromboxane in response to a standard vessel injury was evaluated. Basal thromboxane production, measured as the primary metabolite, thromboxane B2, in blood oozing from the bleeding-time site, was highest among hostile Type A subjects with significantly lower thromboxane production in hostile Type Bs and all non-hostile groups combined. Following an exercise treadmill test hostile subjects produced more thromboxane than non-hostile ones, and hostile Type As had significantly shorter bleeding times than hostile Type Bs. No significant differences on any measure were observed following a stressful color naming task. The observed interaction of hostility and Type A behavior on bleeding time thromboxane formation links behavior to an adverse aspect of a thrombosis-related parameter thought to be involved in the genesis of cardiovascular disease.