The present study tested the general hypothesis that behavioral attributes most predictive of the incidence of coronary heart disease (CHD) in epidemiological research would also be most predictive of sympathetic autonomic nervous system (ANS) arousal in response to performance challenges. Subjects (n = 50) were challenged to respond rapidly and accurately on three tasks involving either perceptual-motor or cognitive skills, while the experimenter monitored blood pressure, heart rate, and galvanic skin potential. The hypothesis was generally confirmed in that (1) type A subjects showed significantly greater cardiovascular changes indicative of sympathetic ANS arousal than type B subjects, (2) the Rosenman and Friedman structured interview was a better predictor of this arousal than the Jenkins Activity Survey, as is the case in CHD, and (3) the stylistic and behavioral components of the type A pattern (as defined by the structured interview) which are most predictive of CHD were also found to be the best predictors of challenge-induced sympathetic ANS arousal. The implications of these results for refinements in the definition, assessment, and modification of coronary-prone behavior are discussed.
The present study examined the relationship between the Type A coronaryprone behavior pattern and the magnitude of cardiovascular response induced by varying levels of environmental challenge. In a 2 × 2 experimental design, Type A and B (noncoronary‐prone) subjects (n= 80) were randomly assigned to either high or low challenge instructional conditions for both the cold pressor (CP) and a choice reaction time task (RT). Overall, across both tasks, Type A subjects responded with greater systolic blood pressure (SBP) and heart rate (HR) elevation than Type B subjects. While these differences between the Types tended to be larger in the high challenge condition, some differences were also observed under low challenge. Component analyses of the Pattern revealed that high hostile/competitive Type A's responded to both low and high challenge instructions in the CP and RT tasks with physiologic elevations comparable to that displayed by globally defined Type A's receiving high challenge instructions. The present findings tentatively suggest that (a) high hostile/competitive Type A's respond to even mild challenge with enhanced physiologic response; (b) globally defined A's tend to evidence the physiologic elevations when specifically challenged; and (c) Type B's show much smaller physiologic reactions to such challenges. Consistent with previous research, comparison of Type A assessment techniques revealed that the Rosenman diagnostic interview was a better predictor of physiologic response than other questionnaire methods. Two hypotheses are advanced and future research recommended regarding possible relationships between environment, behavior, physiology, and disease.
Physiologic measures were recorded in Type A1 (n = 10) and Type B (n = 14) subjects while they engaged in a reaction-time task after receiving instructions emphasizing the need for rapid and accurate performance. Although resting levels were not significantly different, Type A's responded with significantly greater increases than B's in both heart rate and systolic blood pressure, suggesting greater sympathetic arousal. A significant baseline difference between the Types in heart rate variability was also observed suggesting greater lability in sympathetic-parasympathetic function in Type A's. No differences between the Types were obtained for either galvanic skin potential (GSP) or speed of reaction. It is suggested that the paradigm used in the present study offers an inexpensive and efficient means by which cardiovascular reactivity in Type A's and B's may be explored in other and larger groups of subjects.
The effects of altitude acclimatization on blood composition were studied in eight University of Missouri (elev 700 ft) coeds who lived on the summit of Pikes Peak (elev 14,000 ft) for 10 weeks. During the period of altitude exposure the following changes were observed: a transient increase in heart rate, the maximum being reached on 1st day of exposure; an early rapid increase in hematocrit and hemoglobin which later became more gradual; an early and sustained reduction in plasma volume; a rapid initial increase and a more gradual later increase in plasma protein concentration which was attributable to elevations in both the albumin and the globulin fractions; a sustained decrease in the albumin-to-globulin ratio; a slight but sustained increase in serum oncotic pressure; a slight but sustained decrease in blood water content and serum osmolarity; and finally, an unaltered total leukocyte count, but a significant increase in lymphocytes and significant decrease in monocytes. It is concluded that the hematopoietic response to altitude is markedly less in women than that usually observed in men. In women at least, dietary iron supplementation enhances the rate of hematocrit increase at altitude. And finally, the loss of plasma volume is felt to be real and not due to simple dehydration. high altitude; hypoxia; blood volume; blood hydration; plasma proteins; hematopoiesis; leukocytes; sex differences; iron supplement Submitted on April 3, 1968
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