World Journal of Medical Sciences 1 (2): 90-92, 2006 ISSN 1817-3055 © IDOSI Publications, 2006 Corresponding Author: Mr. A.S. Oyadeyi, Department of Physiology, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo State, Nigeria 90 Resting Blood Pressure and Blood Pressure Reactivity: Contributions to Experimental Pain Report in Healthy Males A.S. Oyadeyi, A.O. Afolabi, F.O. Ajao and G.F. Ibironke Department of Physiology, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo State, Nigeria Abstract: It is not known whether it is the resting blood pressure or the pain-induced blood pressure changes (blood pressure reactivity) that contributes to sex differences in nociception. The study investigated whether the relationship between sex and experimental pain report was explained by blood pressure at rest, or during pain task, or both in healthy, young adult males. Fifty-eight apparently healthy male subjects had their blood pressure, heart rate measured pre- and post- a cold pressor test. Pain threshold and tolerance were calculated. Univariate analyses indicated significant positive correlation between baseline systolic blood pressure, systolic blood pressure reactivity, heart rate, reactivity, but not baseline diastolic blood pressure, diastolic blood pressure reactivity, heart rate, weight, height and pain sensitivity. However none of the positively correlated parameters cloud significantly product pain threshold or pain tolerance. Both resting blood pressure and blood pressure reactivity contribute significantly to nocicepyive processing in males, however they do not completely explain nociceptive behaviour in males. Key words: Blood pressure %heart rate %pain %blood pressure reactivity INTRODUCTION greater blood pressure increases [5]. It is therefore Experimentally induced pain in healthy human blood pressure reactivity i.e. pain-induced changes in subjects under controlled laboratory conditions often blood pressure may be positively associated with pain yields differentiated results, with women reporting more threshold and/or pain sensitivity. This was the pain than men [1, 2]. Scientific efforts to explain sex- hypothesis tested in the study using healthy male related difference in pain sensitivity between the sexes volunteers. Since there is a possible link between have focused on first order biological factors including anthropometric indices and blood pressure, the study genetic and anatomical differences. However, given the further examined the possible correlation between well-established differences between men and women in height and weight and pain sensitivity. many cardiovascular parameters, blood pressure must be considered in any attempt to explain sex differences in METHODS pain sensitivity [3]. Fillingim and Mixner [4] assessed the impact of Participants: Fifty-eight female undergraduate students resting blood pressure on sex differences in pain aged 21 to 31 years (means = 22.4, SD 2.78) participated in reactivity in 23 female and 25 male subjects. Sex the study after informed consent was obtained in differences occurred only in the ratings of intensity accordance with guidelines of the research ethics for suprathreshold heat stimuli and in ischemic pain committee at the Ladoke Akintola University. Exclusion tolerance thresholds with women appearing more criteria were ill-health, smoking, recent caffeine intake and sensitive to pain. However the men had higher blood prior experience with the cold pressor a test. pressure then the women. Consequently, blood pressure could be a powerful influence on sex differences in pain Blood pressure measurement: Baseline blood pressure sensitivity. (BBP) and baseline heart rate (BHR) were calculated as the Women and men differ in their blood pressure mean of three measures during the resting baseline period. responses to acute stress, with men generally showing The BP and HR readings taken after hand immersion conceivable that apart from resting blood pressure,