ORIGINAL ARTICLE

Revisiting Cardiovascular Reflexes and Resetting in Healthy Adolescents to Analyse Mechanisms of Physiological and Pathophysiological Factors Influencing Individual Blood-Pressure Components

Background and objectives: Understanding oscillations of cardiovascular parameters (BP, HR, blood flow, heart contractility, etc.) has been a puzzling issue. This paper intends to assess the effects of various physiological and pathological factors like gender, age, BMI, handedness acute perceived stress and chronic perceived stress on individual components of blood pressure, and to evaluate and gauge the physiological and pathophysiological reflex mechanisms for the same.
Methods: 120 normotensive, healthy adults were included with equal gender ratio. After obtaining consent, age, BMI, Handedness and STAI for perceived acute and chronic stress were recorded. BP components i.e. SBP, DBP, PP, MAP and RPP were recorded and calculated. Physical, psychological, physiological and pathological factors affecting cardiac and vascular systems were deliberated. Mean, SD, T-test and Pearson’s correlation were used for analysis.
Results: Gender difference in BP showed cardiac and vascular protective role of oestrogen in females through eNOS. Age had significant negative correlation with RPP suggesting early changes in cardiac mass reducing oxygen extraction by the myocardium, while based on various neuroendocrinal, hormonal and renal mechanisms, BMI showed strong positive correlation with SBP, DBP and MAP, proposing changes within circulating blood volume, cardiac output and large vessels. Unlike previous studies, there was no correlation between handedness and BP components on subjects at rest, suggesting cerebral dominance on autonomic influences might be active only in BP stimulating situations. Acute perceived stress showed negative correlation with all BP components recommending extended biopsychosocial model and active baroreceptor reflex unlike acute physical stress, which shows elevated BP, which can only be obtained by resetting threshold response of baroreceptor to higher level. Chronic perceived stress correlated with elevated SBP and MAP suggesting rumination, cardiovascular remodelling, reflex adaptation and resetting.  
Conclusion: Our study has tried to hypothesise specific physiological and pathophysiological mechanisms which might be involved in changes of individual blood pressure components. It is fascinating to notice that none of the observed factors (physiological and pathological) has any correlation with Heart Rate. Our subjects were at rest and hence, heart rate was normal, showing no variations. This article helps to understand probable underlying mechanisms for the same.