Differences In Cardiovascular Responses Research Articles

Impaired Cardiovascular Responses To Acute Exercise In Adults With Cerebral Palsy

Cerebral palsy (CP) is a non-progressive and permanent neurological disorder leading to musculoskeletal dysfunction and immobility. A major clinical problem with CP is early development of cardiovascular diseases with increased rates of mortality. Due to the inevitability of motor dysfunction adults with CP can develop health risk factors, such as obesity and hypertension, at a higher rate compared to the general population. To date, the physiological basis for CP has not been established; how cardiovascular dynamics, such as heart rate (HR), blood pressure (BP), and blood flow (BF), are controlled in individuals with CP has never been identified. PURPOSE: To determine differential cardiovascular responses to acute dynamic exercise in adults with CP. METHODS: Total of ten adults with and without CP participated in the study. HR from ECG, beat-to-beat arterial BP from Finapres and brachial BP, and respiration via pneumobelt were continuously measured before, during and after 2 minutes of dynamic handgrip exercise at 35% and 50% of maximal voluntary contraction. In addition, diameter, blood velocity, and flow of the brachial artery were measured using Doppler ultrasound on the contracting arm throughout the experiment. RESULTS: HR was significantly increased to exercise from rest in both groups with no group differences (∆9.8±1.2 control vs. ∆10.1±8.4 CP, bpm). Both control and CP groups had increases in BF during exercise compared to at rest (∆132±22 control vs. ∆75±32 CP, ml/min). Mean BP was significantly increased to exercise from rest in control; however, there were only minor changes in BP to exercise from rest in CP group (∆7.2±1.6 control, ∆2.2±0.1 CP, mmHg). CONCLUSION: While HR and BF increased to exercise from rest in similar fashion, BP did not change to exercise in adults with CP. Our preliminary data speculate that other mechanisms, possibly vascular contribution from non-contracting limbs, may contribute to impaired BP response during exercise in CP. Supported by CASA RSCA Infusion, Central RSCA, and Undergraduate Research Grant, SJSU

Oral saline consumption and pressor responses to acute physical stress.

Study 1: Determine the time point where total blood volume and serum sodium were elevated following saline consumption. Study 2: Examine the BP response to isometric handgrip (HG) and the cold pressor test (CPT) following saline consumption. Study 1: Eight participants drank 423 mL of normal saline (sodium 154 mmol/L) and had blood draws every 30 min for 3 h. Study 2: Sixteen participants underwent two randomized data collection visits; a control and experimental visit 90 min following saline consumption. Participants underwent 2 min of isometric HG, post exercise ischemia (PEI), and CPT. Study 1: Total blood volume (3.8 ± 3.0 Δ%) and serum sodium (3.5 ± 3.6 Δ%) were elevated (P < 0.05) by the 90 min time point. Study 2: There were no differences in mean arterial pressure (MAP) during HG (EXP: 17.4 ± 8.2 ΔmmHg; CON: 19.1 ± 6.0 ΔmmHg), PEI (EXP: 16.9 ± 11.7 ΔmmHg; CON: 16.9 ± 7.8 ΔmmHg), or the CPT (EXP: 20.3 ± 10.8 ΔmmHg; CON: 20.9 ± 11.7 ΔmmHg) between conditions (P > 0.05). MAP recovery from the CPT was slower following saline consumption (1 min recovery: EXP; 15.7 ± 7.9 ΔmmHg, CON; 12.3 ± 8.9 ΔmmHg, P < 0.05). Data showed no difference in cardiovascular responses during HG or the CPT between conditions. BP recovery was delayed by saline consumption following the CPT.

Cardiovascular response and sequelae after minimally invasive surfactant therapy in growth-restricted preterm infants.

To study cardiovascular response to minimally invasive surfactant therapy in preterm infants with and without foetal growth restriction (FGR). Poractant alfa was administered and echocardiograms were performed before and 30 min after. FGR infants were compared with those appropriate for gestational age (AGA). Ten FGR infants were compared with 20 AGA infants (gestation [weeks], 28.9 ± 2 vs. 28.6 ± 1, p = 0.55 and birthweight [g], 813 ± 157 vs. 1141 ± 257, p = 0.01, respectively). The change in echocardiographic parameters was more prominent in AGA infants ([global contractility] fractional area change [FAC, %], FGR, 24.7 ± 2.2 to 27.9 ± 0.4, p = 0.08 vs. AGA, 26.6 ± 3 to 30.5 ± 1, p < 0.01, and [longitudinal contractility] tricuspid annular plane systolic excursion [mm], FGR, 3.9 ± 0.3 to 4.6 ± 0.5, p = 0.003 vs. AGA, 4.6 ± 0.3 to 5.5 ± 0.4, p = 0.0001). Significant difference was noted for change in FAC (%), FGR 2.1 ± 1.7 vs. AGA 4.1 ± 1.2, p = 0.02. Differential cardiovascular response to minimally invasive surfactant therapy amongst FGR infants may reflect an in-utero maladaptive state.

Effects of body weight support and gait velocity via antigravity treadmill on cardiovascular responses early after total knee arthroplasty.

To investigate the effects of body weight support (BWS) and gait velocity on cardiovascular responses during walking on an antigravity treadmill early after unilateral and bilateral total knee arthroplasty (TKA).This study was a cross-sectional study design. Fifty patients (7 males and 43 females; average age, 72.0 ± 5.1 years) at 4 weeks after unilateral (n = 25) and bilateral (n = 25) primary TKA were enrolled in the study. Subjects walked on an antigravity treadmill at speeds of 2.5 km/hour and 3.5 km/hour with 3 levels (50%, 25%, and 0%) of BWS. Cardiovascular responses were monitored by measuring oxygen consumption (VO2), heart rate (HR), systolic and diastolic blood pressure (SBP/DBP), the respiratory exchange ratio (RER), and rate pressure product (RPP). Borg rating of perceived exertion (RPE) and a visual analog scale (VAS) of knee pain were recorded immediately after each trial.There were no significant differences in cardiovascular responses between the unilateral and bilateral TKA groups. In the repeated measures Analysis of Variance, VO2 levels, HR, RPP, RPE, RER, and VAS were significantly increased in proportion to 3 levels (50%, 25%, and 0%) of BWS for unilateral and bilateral TKA groups, respectively. Meanwhile, SBP and DBP were unaffected by differences in BWS. At 3.5 km/hour, VO2, RPE, and RER values were statistically greater than those at 2.5 km/hour under the same BWS conditions.We found that the reduction in the metabolic demand of activity, coupled with positive pressure on the lower extremities, reduced VO2 and HR values as BWS increased.Cardiovascular responses vary according to BWS and gait velocity during antigravity treadmill walking. BWS rather than gait velocity had the greatest effect on cardiovascular responses and knee pain.

Gender differences in cardiovascular response to upper extremities isometric exercise in normotensive young subjects

Background: Isometric exercises are a part of our activities and many occupational task. Isometric exercises produce a characteristic increase in blood pressure (BP). These provide pressor stimuli to the cardiovascular system, through efferent sympathetic pathways, with a resultant increase in heart rate (HR) and BP. Although isometric exercise such as handgrip testing has been reported to cause an increase in cardiovascular parameters, the response depends on the volume of muscle mass involved, duration, intensity, number of contraction, and workload. Previously a number of studies have been done to study the gender variation in cardiovascular response to upper extremities handgrip exercises but have shown conflicting results. Hence, this study is an endeavor to evaluate the difference in cardiovascular response to isometric exercise in normotensive young males and females. Aims and Objectives: The aim of the study was to determine the HR and BP response to isometric exercise in healthy normotensive males and females. Materials and Methods: One hundred medical students; 50 males and 50 females of age group 18–22 years satisfying the inclusion criteria were selected. Anthropometric measurements, that is, height and weight were taken. Resting BPs systolic BP (SBP) and diastolic BP (DBP) were recorded. Isometric contraction was held till 60 s using the handgrip dynamometer at 40% of the maximal voluntary contraction (MVC). Post-exercise HR and BP were recorded and compared. Results: Isometric handgrip exercise induces a pressor response and causes an increase in the HR and BPs irrespective of gender. Conclusion: This study concludes that isometric exercise brings about an increase in HR and BP. The response being more pronounced in males than in females.

Differential cardiovascular responses to cutaneous afferent subtypes in a nociceptive intersegmental spinal reflex

Electrical stimulation to segmental dorsal cutaneous nerves (DCNs) activates a nociceptive sensorimotor reflex and the same afferent stimulation also evokes blood pressure (BP) and heart rate (HR) responses in rats. To investigate the relationship between those cardiovascular responses and the activation of nociceptive afferents, we analyzed BP and HR responses to electrical stimulations at each DCN from T6 to L1 at 0.5 mA to activate A-fiber alone or 5 mA to activate both A- and C-fibers at different frequencies. Evoked cardiovascular responses showed a decrease and then an increase in BP and an increase and then a plateau in HR. Segmentally, both cardiovascular responses tended to be larger when evoked from the more rostral DCNs. Stimulation frequency had a larger effect on cardiovascular responses than the rostrocaudal level of the DCN input. Stimulation strength showed a large effect on BP changes dependent on C-fibers whereas HR changes were dependent on A-fibers. Additional A-fiber activation by stimulating up to 4 adjacent DCNs concurrently, but only at 0.5 mA, affected HR but not BP. These data support that cutaneous nociceptive afferent subtypes preferentially contribute to different cardiovascular responses, A-fibers to HR and C-fibers to BP, with temporal (stimulation frequency) and spatial (rostrocaudal level) dynamics.

The mindful attention and awareness scale is associated with lower levels of high-frequency heart rate variability in a laboratory context.

Trait mindfulness has been associated with well-being. A key component of trait mindfulness is intentional attention and awareness which is most commonly measured by the Mindful Attention and Awareness Scale (MAAS). This study investigated the relationship between the MAAS and cardiovascular (HF-HRV, heart rate) reactivity to two laboratory stressors that evoked different patterns of change in heart rate (HR). One stressor (viewing a video of a surgery) evoked HR deceleration while the other stressor (mental arithmetic) evoked HR acceleration. Undergraduate students completed the MAAS and were then exposed to the two stressors while ECG (electrocardiography) was recorded. Findings support the reliability of the stressors to induce expected differential cardiovascular responses and explicate the role of parasympathetic activation. Further, a main effect for MAAS was observed indicating that across laboratory conditions, persons scoring higher on the MAAS had lower HF-HRV relative to persons scoring lower on the MAAS. These findings suggest that higher levels of intentional attention and awareness in a laboratory context might promote parasympathetic withdrawal because these participants were more vigilant, experienced higher cognitive load, and detected more threat cues. Implications for the MAAS and cardiovascular responses to stress are discussed.

Sex differences in cardiovascular responses to orthostatic challenge in healthy older persons: A pilot study.

Premenopausal women show a higher incidence of orthostatic hypotension than age-matched men, but there are limited data available on sex differences in cardiovascular responses to orthostatic challenge in healthy older persons. We investigated sex differences in hemodynamic and autonomic responses to orthostatic challenge in healthy older males and females. Fourteen older healthy women and 10 age-matched men performed a sit-to-stand test (5min of sitting followed by 5min of standing). A Task Force® Monitor continuously measured the following beat-to-beat hemodynamic parameters: heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, stroke index, cardiac index, and total peripheral resistance index. Cardiac autonomic activity, low-frequency (LF: 0.04-0.15Hz) normalized (LFnuRRI) and high-frequency (HF: 0.15-0.4Hz) normalized (HFnuRRI) components, and the ratio between LF and HF power (LF/HF) were calculated using power spectral analysis of heart rate variability. Across all hemodynamic parameters, there were no significant differences between the sexes at baseline and during standing. LFnuRRI (median: 70.2 vs. 52.3, p < 0.05) and LF/HF ratio (median: 2.4 vs. 1.1, p < 0.05) were significantly higher, whereas HFnuRRI (median: 29.8 vs. 47.7, p < 0.05) was lower among women at baseline. All other heart rate variability measures did not differ between the sexes. The data indicate that older women showed higher sympathetic and lower parasympathetic activity at rest compared to age-matched men. These results are contradictory to the observations from previous studies, which showed a reduced sympathetic and enhanced parasympathetic activity in women in all ages. Further studies are required to determine the underlying mechanisms contributing to higher incidence of orthostatic hypotension in older females.

The reaction of the circulatory system to stress and electromagnetic fields emitted by mobile phones - 24-h monitoring of ECG and blood pressure

Experimental studies have shown cardiovascular effects of electromagnetic fields (EMF) emitted by mobile phones (e.g., prolonged QTc interval and abnormal blood pressure [BP] values). Also, stress may have an impact on the cardiovascular function. However, there are practically no data regarding the joint effect of exposure to stress and EMF, with both factors pertaining, e.g., to employees of mobile network operators. Out of 208 subjects who had taken part in survey research, 55 workers agreed to undergo resting ECG, 24-h ECG and ambulatory blood pressure monitoring (ABPM). Their health condition, occupational and life-stress levels and EMF exposure were also assessed. Among the workers using mobile phones for more than 60 min daily, the systolic BP values in office measurement and at night-time in ABPM were significantly higher than among the workers spending less time talking on mobile phones (p = 0.04 and p = 0.036, respectively). The workers with the highest level of occupational stress showed significantly higher systolic 24-h BP (p = 0.007) and at day-time (p = 0.002), both during work (p = 0.010) and after work (p = 0.005), and higher diastolic BP values at day-time (p = 0.028). Cardiovascular response was strongly gender-related: males showed more BP abnormalities while females displayed more impairments in ECG records. The heart rate from 24 h was significantly correlated with the level of occupational stress, after adjusting for gender, life-stress and EMF. The findings obtained thus far have indicated the need to conduct in-depth studies on the impact of stress and EMF emitted by mobile phones on the health effects, in order to clarify the observed gender-related differences in cardiovascular response to the combined exposure to stress and EMF. Med Pr. 2019;70(4):411-24.

Differential Cardiovascular Responses to Acute Exercise in Children with Autism Spectrum Disorder

Differential Cardiovascular Responses to Acute Exercise in Children with Autism Spectrum Disorder

Effects of Estrogen in Gender-dependent Fetal Programming of Adult Cardiovascular Dysfunction.

Epidemiological studies and experimental studies have demonstrated that intrauterine adverse environment increases the risk of Cardiovascular Disease (CVD) in adulthood. However, whether an individual develops a cardiovascular dysfunctional phenotype may depend on genetic background, age, and sex. In this review, we summarize some of the recent experimental animal studies in the developmental programming of adult CVD with an emphasis on sex differences and the potential role of estrogen in mediating sexual dimorphism. Few epidemiological studies report the effect of sex on the developmental programming of CVD. However, numerous experimental animal studies have shown a sex difference in fetal programming of adult cardiovascular dysfunction. Most of the animal studies indicate that male offspring develop cardiovascular dysfunction and CVD in adulthood, whereas adult females appear to be protected. Estrogen is one of the key factors that contributes to the sex difference of adult CVD. Estrogen/its Receptor (ER) may interact with the RAS system by changes of DNA methylation patterns at the target gene promoter, serve as an antioxidant to counteract the prenatal insults-induced heightened ROS, and function as an eNOS activator to increase vasodilation, resulting in the protection of female offspring from the development of hypertension and other CVDs. These studies suggest that estrogen/ER may contribute to sex differences in cardiovascular response to an adverse intrauterine environment and play a significant role in modulating the cardiovascular response in adulthood.

A cross-sectional study of gender differences in cardiovascular responses to orthostatic tolerance test in adolescents

Background: Clinical data show higher incidence of postural hypotension in women than men. Clinicians make use of orthostatic tolerance test (OTT) to investigate such a situation and also in other varieties of clinical disorders ranging from most common disorders such as diabetes, hypertension leading to autonomic neuropathy to very rare disorders such as Shy-Drager syndrome and dysautonomias. This study will help to assess gender differences in cardiovascular response to orthostatic challenge. Aims and Objectives: The objective of the study was to evaluate the gender differences in cardiovascular responses such as change in systolic blood pressure (BP), diastolic BP, heart rate (HR), and mean arterial pressure (MAP) during OTT in 16–20 years of age group. Materials and Methods: The present cross-sectional study was conducted in 34 males and 36 female students of the age group of 16–20 years. The autonomic test used to assess orthostatic tolerance was OTT which is widely used for routine clinical evaluation of autonomic dysfunction. HR and BP changes during the orthostatic challenge were recorded, and 30:15 ratio was calculated from R-R interval of electrocardiogram ECG recording during the challenge. Results: Among the baseline parameters of males and females only HR, diastolic BP, and MAP were comparable. BP response during orthostatic challenge showed that MAP was significantly lower for females than males (P < 0.05). HR response was not statistically significant. Conclusion: The values being significantly lower for females than males this study helped to support the fact that women have less responsiveness to BP regulation during an orthostatic challenge in adolescents.

Abstract 16684: Cardiovascular Responses of Persons With ABI to Computerized Motor-Cognitive Assessments

Introduction: Recent evidence suggests that a traumatic brain injury is associated with a higher risk for cardiovascular pathology and impaired responses to activities of daily living. However, limited standardized testing is available to document cardiovascular responses during motor-cognitive function after acquired brain injury (ABI). Our study aimed to compare cardiovascular responses in persons with and without ABI during motor-cognitive assessments in virtual-reality gaming environments. Hypothesis: We hypothesized that there would be a significant difference in participant effort as defined by cardiovascular response specific to each activity. Methods: 50 participants (M/F = 16/34) age 29.31 (+/-11.667) years with and without ABI (9/41) performed a timed, 4-square stepping task to test dynamic balance (4SST) and the standardized Montreal Cognitive Assessment (MoCA).Testing included polar heart monitoring of participant effort via heart rate (HR) while performing five standardized, virtual-reality games to test motor-cognitive skills. Variables included HR, 4SST time, MoCA score, and computerized Cognitive Scores (ICOG). Descriptive statistics explored group performance using SPSS 24.0 (IBM) and an alpha level of 0.05. Results: results Indicated similar performance in MoCA and ICOG scores (26.78 +/- 2.188, 28.043 +/- 2.230 respectively) but ICOG effort ratings were significantly higher in the ABI group compared to without ABI (2.60 +/- 1.140 vs. 1.60 +/- 1.095 respectively). Also, the ABI group took significantly longer to complete each ICOG activity (34.056 +/- 24.461 vs. 29.964 +/- 25.727 respectively) with significantly delayed reaction times (3.598+/- 1.542 vs. 2.825 +/- 1.630 respectively). Significant relationships occurred between the ICOG activity score and the associated HR (r = - 0.512, p = 0.030) and 4SST and AGE (r = 0.526, p = 0.025). Multiple regression analysis indicated history of concussion, previous night hours of sleep, MoCA scores, gender, and HR significantly explained 61.2% of the ICOG variance (p = 0. 005). Discussion: Results indicate significant differences in cardiovascular responses to motor-cognitive activities however similar performance in MoCA and ICOG scores. There was also a significant difference in effort and reaction time scores. This trend appeared to explain overall ICOG performance as presented by the regression analysis. Conclusions: Preliminary findings warrant further research of cardiovascular responses during specific motor-cognitive tasks common to ADL’s.

Effect of uphill, level, and downhill walking on cardiovascular parameters among young adults

BACKGROUND: Uphill walking and downhill walking are the different forms of walking which causes cardiovascular changes in the body. By changing the gradient of the treadmill, we can change the severity of exercise by keeping the speed constant. AIM: This study aims to evaluate the cardiovascular changes during uphill, level, and downhill walking in young adults. STUDY DESIGN: This was an experimental study MATERIALS AND METHODS: Twenty participants (15 males and 5 females) having normal body mass index were made to walk on the treadmill at different gradients of −15%, 0%, and +15% at a preferential speed for a constant duration of 15 min. The heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and rate pressure product (RPP) were recorded before and after walking. STATISTICAL ANALYSIS: Statistical analysis was done by ANOVA test using SPPSS, version 20 (IBM, Bangaluru, Karnataka ,India), where P RESULTS: There was a significant increase in HR (105.8 ± 20.06), SBP (133.3 ± 13.54), and RPP (14146 ± 3025) during uphill walking as compared to downhill and level walking. There were no significant changes in cardiovascular parameters when level walking and downhill walking were compared. DBP did not show any significant changes at any gradient of walking. CONCLUSION: Cardiovascular response increases during uphill walking, but level walking and downhill walking show no difference in cardiovascular response. These findings can be used to prescribe the exercises for young adults.

P05.08: Differences in pre‐pregnancy stress response between healthy and PE/FGR pregnancies

It is hypothesised that maternal cardiovascular (CV) dysfunction may be present prior to conception. With pregnancy, a decompensation of CV function may manifest as pre-eclampsia (PE) or fetal growth restriction (FGR). We hypothesise that pre-pregnancy (PP) exercise stress testing is comparable to gestation related physiological stress, and may relate to pregnancy outcome. To investigate this, we prospectively examined PP exercise stress test responses in healthy women planning to conceive, in association with subsequent pregnancy outcome, specifically PE/FGR. We recruited non-smokers with no CV comorbidities into a pre-conception study. All participants had non-invasive measurements of cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), heart rate (HR) and brachial blood pressure (BP) at rest. These tests were repeated during and after a 3-minute Dundee step test. Delta (δ) values were calculated between resting and subsequent exercise measurements to deduce exercise stress response. For data analysis, women who subsequently conceived a pregnancy affected by PE/FGR were assigned to ‘pathology’ group and those with unaffected pregnancies to a control group. Controls had significantly higher CO (mean CO 10.14 vs 8.76 L/min, p= 0.042) and SV(p=0.016) compared to the pathology group. δTPR between the groups was also statistically different(p=0.007). PE/FGR group have greater peak HR and delta HR values (peak HR[control =99.56 bpm, pathology =111/33bpm, P=0.002] and δHR response [control mean=17.87 bpm, pathology mean=26.72 bpm P=0.032]). We report differences in cardiovascular response to stress between women who subsequently conceive a pregnancy affected by PE/FGR and those with normal pregnancy outcome. Normal stress response is increased CO and reduced TPR. CO increments by increasing SV was more pronounced in controls, whereas the pathology group had more pronounced HR increase.

Experimental dyspnea as a stressor: differential cardiovegetative responses to inspiratory threshold loading in healthy men and women.

Dyspnea is associated with an emotional reaction that involves limbic activation. The inspiratory threshold load (ITL) is known to elicit a dyspneic response in healthy subjects. Laboratory-induced stress conditions have been shown to elicit sex-related differences in cardiovascular responses. The aim of this study was to evaluate how healthy men (n = 8) and women (n = 9) react and adapt to 5-min periods of ITL at three levels (low, medium, and high) in terms of heart rate (HR), temporal (RMSSD) and spectral (LF, HF, LF/HF ratio) HRV indexes, and rating of breathing discomfort. HR increased with low, medium, and high ITL in men, whereas it increased only with high ITL in women. LF/HF ratio increased at low ITL in both men and women. Modifications appear to depend essentially on increased LF in men and on reduced HF in women. In addition, HRV modifications differ between men and women, following the order of presentation of ITLs. Our results show a continuous and sustained stress in men (increased HR, LF, and LF/HF ratio across ITL presentation) and a stress adaptation in women. Subjective responses of breathing discomfort were not correlated with sympatho-vagal balance modifications for a subgroup of subjects (n = 10). Breathing against the ITL induced autonomic modifications that are different between men and women, i.e., driven by sympathetic mediated responses in men, whereas women showed a greater parasympathetic modulation of cardiovascular activity. These results highlight the role of the mechanical inspiratory load in the heart rate variability seen in chronic obstructive pulmonary disease.NEW & NOTEWORTHY Breathing against the ITL induced autonomic modifications driven by sympathetic mediated responses in men, whereas women showed a greater parasympathetic modulation of cardiovascular activity, even for low load. A stress circuit could be at the origin of autonomic modifications induced by ITL. Our results would underline the role of the mechanic inspiratory load in the abnormalities in heart rate variability seen in COPD patients.

Differences in Cardiovascular Responses to Alamandine in Two-Kidney, One Clip Hypertensive and Normotensive Rats.

Alamandine is a newly discovered component of the renin-angiotensin system, which regulates blood pressure. In this study, the effect of alamandine on cardiovascular parameters in two-kidney, one clip (2K1C) hypertensive rats and normotensive rats, and the possible roles of the angiotensin II type 1 receptor (AT1R) and the PD123319-sensitive receptors in mediating this effect was investigated.Methods and Results:The cardiovascular parameters were monitored for 10 min before the infusion of the drugs or saline, and for 30 min afterward. In the 2K1C hypertensive rats, alamandine caused brief increases in mean arterial pressure (MAP), left-ventricular systolic pressure (LVSP) and maximum rate of pressure change in the left ventricle (dP/dt(max)). This was followed by decreases in these parameters, which extended throughout the remainder of the infusion period. Losartan, an AT1R blocker, abolished alamandine's initial pressor effect and PD123319, which can block AT2R and Mas-related G protein-coupled receptor D (MrgD) receptors, partially decreased the late depressor effect. Left ventricular end-diastolic pressure (LVEDP) decreased during alamandine infusion; this effect was reduced by PD123319. In the normotensive rats, alamandine increased MAP, LVSP, dP/dt (max), and it decreased LVEDP during the infusion period. These effects of alamandine were reduced by losartan. The results of this investigation suggest that, under normal conditions, alamandine acts via AT1R, but in pathological conditions such as hypertension, its effect on PD123319-sensitive receptors masks its effect on AT1R.

Age differences in physiological responses to self-paced and incremental dot{V}{text{O}}_{2hbox{max} } testing

PurposeA self-paced maximal exercise protocol has demonstrated higher dot{V}{text{O}}_{2hbox{max} } values when compared against traditional tests. The aim was to compare physiological responses to this self-paced dot{V}{text{O}}_{2hbox{max} } protocol (SPV) in comparison to a traditional ramp dot{V}{text{O}}_{2hbox{max} } (RAMP) protocol in young (18–30 years) and old (50–75 years) participants.MethodsForty-four participants (22 young; 22 old) completed both protocols in a randomised, counter-balanced, crossover design. The SPV included 5 × 2 min stages, participants were able to self-regulate their power output (PO) by using incremental ‘clamps’ in ratings of perceived exertion. The RAMP consisted of either 15 or 20 W min−1.ResultsExpired gases, cardiac output (Q), stroke volume (SV), muscular deoxyhaemoglobin (deoxyHb) and electromyography (EMG) at the vastus lateralis were recorded throughout. Results demonstrated significantly higher dot{V}{text{O}}_{2hbox{max} } in the SPV (49.68 ± 10.26 ml kg−1 min−1) vs. the RAMP (47.70 ± 9.98 ml kg−1 min−1) in the young, but not in the old group (>0.05). Q and SV were significantly higher in the SPV vs. the RAMP in the young (<0.05) but not in the old group (>0.05). No differences seen in deoxyHb and EMG for either age groups (>0.05). Peak PO was significantly higher in the SPV vs. the RAMP in both age groups (<0.05).ConclusionFindings demonstrate that the SPV produces higher dot{V}{text{O}}_{2hbox{max} }, peak Q and SV values in the young group. However, older participants achieved similar dot{V}{text{O}}_{2hbox{max} } values in both protocols, mostly likely due to age-related differences in cardiovascular responses to incremental exercise, despite them achieving a higher physiological workload in the SPV.

Sex Differences in Cardiovascular Response to Handgrip Exercise among Apparently Healthy Young Adult Nigerians

Background Sustained handgrip is one of the standardized non invasive test involved in assessment of cardiac autonomic functions Objective This study aimed at determining the sex differences in cardiovascular response to sustained handgrip among apparently healthy young adult Nigerians Materials and Method females and males age and sex matched apparently healthy young adults aged between years participated in this study The Systolic Blood Pressure SBP Diastolic Blood Pressure DBP and Pulse Rate PR of the subjects were recorded before and during sustained handgrip exercise in sitting position with sphygmomanometer cuff attached to the dominant arm The maximum voluntary contraction MVC of the subject was determined from the non dominant arm by the use of a handgrip dynamometer The handgrip was maintained at of the maximum voluntary contraction for as long as possible up to maximum period of minutes Blood pressure was monitored every minute until the maximum values were obtained Mean Arterial Pressure MAP Pulse Pressure PP and Rate Pressure Product RPP were calculated from SBP DBP and PR Data were analyzed using descriptive and inferential statistics The student t test was used to determine the difference between two groups and p value lt was considered statistically significant Results The males had a higher resting SBP DBP MAP PP and RPP than females with significant sex difference in PP t p value lt and SBP t p value Significant sex differences were observed in maximum values of SBP t p value lt DBP t p value MAP t p value RPP t p value and PP t p value during sustained handgrip exercise The resting heart rate at rest and during sustained handgrip exercise were higher in females Significant sex differences were also observed in change in cardiovascular responses to sustained handgrip with regards to SBP t p value DBP t p value and MAP t p Conclusion This study showed that sex significantly influenced haemodynamic responses to sustained handgrip exercise

Gender differences responses in isometric exercise

Abstract: Gender differences in cardiovascular responses to isometric exercise for sitting posi-tion and spine.The purpose of this study was to 1) determine whether cardiovascular responses to isometric exercise differ between genders, and 2) to determine if the behavior affects cardiovas-cular responses to isometric hand tightening (IHG) exercise.Sixteen women and sixteen men (age 22.6 ± 4.2 years) performed two tests (seated or spine) IHG maximum trials at 40% MVC a week away.Blood pressure (BP) and heart rate (HR) measurements were collected at rest (RT), the first minute of exercise (M1), before failure (PF), and 30 s of recovery after failure (RC).Mean arterial pressure (MAP), pulse pressure (PP), and the rate of pressure produces (RPP) were calculated from BP and HR data.Tests showed considerable time by gender interactions for diastolic blood pressure (DBP) and MAP. Males had DBP significantly higher than women in M1 (105.46 ± 14.97 vs. 92.59 ± 13:14 mmHg), PF (122.46 ± 11.23 vs 109.50 ± 13.72 mmHg) and RC (85, 83 ± 4.11 vs. 73.46 ± 8.35 mmHg) and higher MAP measurements that women in M1 (120.32 ± 13.76 vs 105.43 ± 13.76 mmHg), PF (136.44 ± 8.65 vs. 24.31 ± 13:34 mmHg), and RC (100.44 ± 8.21 vs. 87.67 ± 8.26 mmHg).DBP, MAP, and HR were significantly higher in the sitting position than in the spine position for both sexes.Conclusions: 1) men significantly increase MAP and DBP after starting the exercise submaxi-mal IHG through recovery regardless of position, 2) women have significantly lower measurement of blood pressure than men along the submaximal despite exercising attitude and 3) The attitude has important effects on the cardiovascular response during exercise submaximal IHG.4) The force exerted varies significantly in standing position compared to other positions.