Peripheral Vasomotor Responses Research Articles

Elevated plasma homocysteine levels are associated with impaired peripheral microvascular vasomotor response

BackgroundHyperhomocysteinemia (HHcy) has been proposed as an important cardiovascular risk factor (cRF). However, little is known about the association between plasma homocysteine levels and peripheral microvascular endothelial dysfunction (PMED), which is an integrated index of vascular health. MethodsThis cross-sectional and retrospective cohort study included patients who underwent non-invasive PMED assessment using reactive hyperemia peripheral arterial tonometry (RH-PAT). The association between HHcy and PMED, and its impact on MACE (all-cause mortality and atherosclerotic cardiovascular events) was investigated. ResultsA total of 257 patients were enrolled (HHcy > 10.0 µmol/L, N = 51; lower levels of homocysteine [LHcy] ≤ 10 µmol/L, N = 206). Patients with HHcy were older, predominantly males, and with more comorbidities than patients with LHcy (p < 0.05 for all). RH-PAT index was lower in patients with HHcy versus LHcy (p = 0.01). A significant association between HHcy and PMED was observed in older (≥60 years), obese (≥30 kg/m2), present/past smokers and hypertensive patients. HHcy was significantly associated with PMED even after adjusting for other cRF and B-vitamins supplementation. HHcy was associated with an increased risk of MACE with a hazard ratio of 3.65 (95% CI 1.41–9.48, p = 0.01) and an adjusted hazard ratio of 2.44 (95% CI 0.91–6.51, p = 0.08) after adjustment for age (≥60 years). ConclusionHHcy was independently associated with PMED after adjusting for cRF and B-vitamins supplementation. Thus, the link between homocysteine and MACE could be mediated by endothelial dysfunction, and will require further clarification with future studies.

Effects of Isolated Muscle Training on Vasomotor Response and Peripheral Blood Flow

The vasomotor response, a marker of cardiovascular health, refers to the adaptability of the inner lining of blood vessels to maintain the homeostasis of vascular tone. The two main control systems that underpin this response are: the systemic autonomic control, with the sympathetic branch mediated vasoconstriction, and the endothelial cells response to mechanical and chemical stimuli, that results in smooth muscles cell vasodilation. During exercise the peripheral circulation is mostly mediated by local control, and the peripheral blood flow (BF) increases in all body districts directly involved and not involved by physical exercise. The vasodilation response depends on the magnitude of the stimulus received. To date, vascular adaptations in the brachial artery not involved in an isolated leg muscle training, is still unclear/unknown. Repetitive changes in BF occurring during exercise training may act as vascular training for vessels supplying the active muscle bed and ones distal to the active muscle. Therefore, the study aim was to evaluate the effects of isolated quadriceps muscle training (IQT) on vasomotor response in the lower limb directly involved with exercise (femoral artery) and on the upper limb, not involved with IQT (brachial artery). Ten healthy participants (4 M and 6 F; 23±3 yrs) underwent eight weeks of IQT (3 days/week; ~ 40 min; 50 – 90% WRM) at different intensities. Maximum work rate (MWR) was assessed before, during (every 2 weeks, to redefine the training work‐load) and after IQT. Pre‐ and post‐IQT measurements of vascular function and peripheral BF were performed by flow mediated dilatation (%FMD) in the brachial artery (non‐trained limb), and by passive limb movement in femoral artery (trained limb). After 8 weeks of IQT, MWR and BF in femoral artery increased significantly by 43% and 153%, respectively. No difference in %FMD was found despite 21% increase in brachial artery blood flow during exercise was found. Eight weeks of IQT improved peripheral vasomotor response only in the lower limb directly involved in IQT without affecting vascular functionality in the uninvolved upper limb, suggesting that IQT did not provide a sufficient stimulus to induce adaptations also in other districts' vasculature.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Qigong Effects on Heart Rate Variability and Peripheral Vasomotor Responses.

Population aging is occurring worldwide, and preventing cardiovascular event in older people is a unique challenge. The aim of this study was to examine the effects of a 12-week qigong (eight-form moving meditation) training program on the heart rate variability and peripheral vasomotor response of middle-aged and elderly people in the community. This was a quasi-experimental study that included the pre-test, post-test, and nonequivalent control group designs. Seventy-seven participants (experimental group = 47; control group = 30) were recruited. The experimental group performed 30 min of eight-form moving meditation 3 times per week for 12 weeks, and the control group continued their normal daily activities. After 12 weeks, the interaction effects indicated that compared with the control group, the experimental group exhibited significantly improved heart rate variability and peripheral vasomotor responses.

Application of pulsed-wave Doppler ultrasound to exploration of the peripheral vasomotor response by gender and hand dominance.

Laser Doppler flowmetry measures peripheral vasomotor response but fails to detect changes in vascular diameters, resistance, and heart rates. Because this response contributes to assessing sympathetic disorders and relies on the above variables to be correctly interpreted, we used pulsed-wave Doppler (PWD) ultrasound to evaluate the response and to determine whether it was affected by gender or hand dominance. PWD was applied to bilateral deep palmar branches of the radial arteries of 22 men and 22 women, using post-inspiratory cough as the sympathetic stimulus. Pulsatility index (PI), arterial diameters, heart rates, flow velocity, and blood flow before and after sympathetic stimuli were analyzed for both groups. Women had a higher PI value of the radial arteries at rest; in contrast, that of men was higher after sympathetic stimuli. Blood flow velocity (V max, V max mean, and V mean) at rest was higher for men than for women. A significant difference was observed in V min after stimulus. Arterial diameters and blood flow before and after stimuli were higher for men than for women. Post-inspiratory cough caused significant diameter reduction in women but heart rate elevation in men. Hand dominance had no effect. This study demonstrated the suitability of PWD for detailing peripheral vasomotor response, which was affected by gender but not hand dominance. Our results suggest application of PWD to diseases with unilateral sympathetic impairment, but responses for different sexes should be treated with caution.

Pulsed wave Doppler ultrasonography for the assessment of peripheral vasomotor response in an elderly population

To assess sympathetic vasomotor activity and its changes with age, using pulsed wave Doppler ultrasound. We recruited 20 young adults (24-37 years old) and 20 older individuals (60-81 years old). Pulsed wave Doppler ultrasound was applied over the right radial artery to measure blood flow at rest and after a voluntary inspiratory cough eliciting sympathetic activation. The maximal (Vmax), minimal (Vmin), time-averaged (TAMaxV) blood flow velocity, and the pulsatility index (PI) were calculated and compared between groups. At rest, PI was similar in both groups but Vmax and TAMaxV were higher in the older group (p < 0.05). Vmax, Vmin, and TAMaxV decreased, and PI increased after inspiratory cough in both groups (p ≤ 0.001), but this increase was lower in the older group (p < 0.001). TAMaxV after coughing was higher in the older group (p < 0.05). Heart rate did not differ significantly within or between groups. The older group exhibited reduced vasomotor reactivity of the radial artery after sympathetic stimulus. Peripheral vasomotor response should be interpreted with caution in elderly populations.

The ontogeny of hemodynamic responses to prolonged umbilical cord occlusion in fetal sheep

There is evidence that preterm fetuses have blunted chemoreflex-mediated responses to hypoxia. However, the preterm fetus has much lower aerobic requirements than at term, and so moderate hypoxia may not be sufficient to elicit maximal chemoreflex responses; there are only limited quantitative data on the ontogeny of chemoreflex and hemodynamic responses to severe asphyxia. Chronically instrumented fetal sheep at 0.6 (n = 12), 0.7 (n = 12), and 0.85 (n = 8) of gestational age (GA; term = 147 days) were exposed to 30, 25, or 15 min of complete umbilical cord occlusion, respectively. At all ages, occlusion was associated with early onset of bradycardia, profoundly reduced femoral blood flow and conductance, and hypertension. The 0.6-GA fetuses showed a significantly slower and lesser fall in femoral blood flow and conductance compared with the 0.85-GA group, with a correspondingly reduced relative rise in mean arterial blood pressure. As occlusion continued, the initial adaptation was followed by loss of peripheral vasoconstriction and progressive development of hypotension in all groups. The 0.85-GA fetuses showed significantly more sustained reduction in femoral conductance but also more rapid onset of hypotension than either of the younger groups. Electroencephalographic (EEG) activity was suppressed during occlusion in all groups, but the degree of suppression was less at 0.6 GA than at term. In conclusion, the near-midgestation fetus shows attenuated initial (chemoreflex) peripheral vasomotor responses to severe asphyxia compared with more mature fetuses but more sustained hemodynamic adaptation and reduced suppression of EEG activity during continued occlusion of the umbilical cord.

Valsalva maneuver, Müller maneuver: hemodynamic and reflex mechanisms, relevances

The time honored ancient reflex tests, the Valsalva and Müller maneuvers are still popular in the everyday clinical practice. These maneuvers are capable of imitating both trivial situations and significant pathological conditions. The Valsalva maneuver is still frequently used for the assessment of autonomic neuropathy. Addition of continuous noninvasive blood pressure monitoring allows assessment of both cardiac vagal and sympathetic driven peripheral vasomotor responses. The Müller maneuver has recently gained renewed popularity in simulating episodes of obstructive sleep apnea (OSA). Continuous monitoring of arterial pressure and muscle sympathetic nerve activity (MSNA) casts light on the close relationship between OSA and circulatory abnormalities.

Vasomotor responses to decreased venous return: effects of cardiac deafferentation in humans

We compared haemodynamic and peripheral vasomotor responses to lower body negative pressure (LBNP) in cardiac transplant recipients who had undergone bicaval anastomoses, involving right atrial deafferentation (-RA), and the conventional procedure in which some atrial baroreceptor afferents remain intact (+RA). We measured mean forearm blood flow (FBF) responses using Doppler/ultrasound during three randomised trials involving 0 (baseline), -20 and -40 mmHg LBNP in 15 transplant recipients (9 -RA, 6 +RA) and in eight healthy matched controls. A significant effect of LBNP on FBF existed between control and transplant groups (P < 0.05; two-way ANOVA). Mild LBNP (-20 mmHg), significantly decreased FBF by 29.7 +/- 10.0% relative to baseline in +RA subjects (P < 0.05), whereas the 17.7 +/- 10.3% decrease in -RA subjects was not significant. In response to -40 mmHg LBNP, FBF significantly decreased in control (42.4 +/- 4.6%, P < 0.05) and +RA subjects (33.3 +/- 11.4%, P < 0.05) with no significant change in the -RA group. The response of systolic blood pressure (SBP) to -40 mmHg significantly differed between groups (P < 0.05): -RA subjects decreased significantly (P < 0.05) whilst the decrease in SBP in +RA subjects did not achieve significance and control subjects exhibited an increase. The heart rate increase from baseline to -40 mmHg was significantly attenuated in -RA relative to controls and the +RA group (P < 0.05). The present study demonstrates that atrial deafferentation impairs reflex vasomotor control of the circulation in response to low- and high-level LBNP, indicating that atrial deafferentation may contribute to abnormal arterial pressure regulation.

Vasomotor Reactivity in Premature Neonates at Term

In order to assess the specific sympathetic reactivity in premature infants at term, we designed a study to evaluate the peripheral vasomotor response of such infants when exposed to auditory challenges. Testing was performed in 29 premature neonates at term in both quiet and active sleep during a morning session. Two types of noises were used (click and continuous tones) at three frequencies (250, 1,000 and 6,000 Hz) and at three intensities (60, 85 and 110 dBA). Vasomotor response was studied by analyzing with Mathlab^® software the variability of the plethysmographic wave of the oxymetric pulse. No behavioral awakening was observed in response to any stimulation. When a tachycardia or a bradycardia reaction to the stimuli was observed, all neonates responded with a vasoconstriction. The global mean of the vasoconstrictive response was 18.45%. The overall ANOVA on the vasomotor response revealed significant effects for sleep stages (t: 1.98; p < 0.05), for frequency (t: 3.3; p < 0.001) and for intensity of noise (t: 3.01; p < 0.03) but no significant response with heart rate variability. From these results, we could conclude that the assessment of the vasomotor response is a very sensitive procedure to determine the reactivity of the autonomic nervous system in neonates, and could be used to study such vegetative responses in other stressful situations with good accuracy.

THE EFFECT OF SLEEP DEPRIVATION ON THERMOREGULATION IN MALES EXPOSED TO 12??C for 180-min

PURPOSE: This investigation evaluated the effects of 33 hrs of sleep deprivation on thermoregulation in six young males (29 ± 6 yrs) during 180 min of cold exposure in 12°C air. METHODS: Subjects underwent two cold air trials (CAT) (12°C air for 180 min): one following a normal night of sleep (i.e., 6–8 hrs) (CON) and one following 33 hrs of sleep deprivation (SDEP). ANOVA was used to determine significance between SDEP vs. CON across time for rectal temperature (Tre), insulation (i), metabolism (M), or mean skin temperature (Tsk). RESULTS: ANOVA revealed no significant differences (P > 0.05) between CON and SDEP for Tre, Tsk, M, and I. A main effect for time was demonstrated for I (p = 0.016), M (p = 0.014), and Tsk (p < 0.001). A significant (p = 0.001) trial x time for Tsk was demonstrated. CONCLUSIONS: Despite the significant difference in peripheral vasomotor response (i.e., Tsk) between SDEP and CON, there were no concomitant differences in metabolic and core temperature during 180 min of cold exposure to 12°C. Subsequent research may consider increasing the thermal stressor to further elucidate thermoregulatory differences.

Reflex cutaneous vasoconstriction during cold pressor test is mediated through alpha-adrenoceptors.

The effects of the cold pressor test on the coronary circulation have been clearly defined but the effects on the peripheral vasculature are less well understood. To measure the peripheral vasomotor response during cold pressor test perfusion in the upper extremity contralateral to the cold immersion was assessed by laser Doppler flowmetry and skin-surface temperature gradients. To identify the mechanism of vasoconstriction, cold pressor test was performed before and after the administration of phentolamine, an alpha-adrenoceptor antagonist. Vasoconstriction during cold pressor test was demonstrated by both skin-surface temperature gradients and by laser Doppler flowmetry. This vasoconstrictor response was significantly attenuated by the administration of phentolamine. The results demonstrate that the cold pressor test induces an alpha-adrenoceptor mediated vasoconstriction in the peripheral vasculature.

The physiological stress response and the role of cognitive coping in migraine patients and non-headache controls

Our study investigated physiological response specifity and cognitive coping in migrainous patients during an achievement task situation. Thirty-three migrainous subjects and thirty-two nonheadache controls were subjected to 40 min of demanding cognitive tasks and 20 min of recovery during which cranial and peripheral vasomotor responses were registered as well as electrodermal and myographic activity. Subjects of both groups were randomly assigned to two experimental conditions, a so-called ‘spontaneous processing condition’ and the ‘positive coping treatment’. In this treatment condition subjects received a short training in the conscious use of positive self-statements in stress situations. Though a specific pattern of cranial vasomotor responses in migraine subjects could be verified by group statistics, this pattern was only found in very few individuals. Reliable differences between groups could not be identified in other physiological variables either. The hypothesis that the predicted cranial vasomotor specifity in migraine subjects correlates with negative cognitive coping habits in migraine subjects best revealed in the ‘spontaneous processing’ condition, was not corroborated. The treatment variation regarding coping produced somewhat paradoxical effects, more relaxed and positive self-evaluation (subjective level) and more arousal (physiological level). Results are discussed for their impact on the psycho-biological model of migraine.

Selective brain cooling is affected by wearing headgear during exercise

The purpose of this work is to relate the concept of selective brain cooling (SBC) during exercise to heat loss from the head while either bare or covered. During hyperthermia, SBC is considered to occur if tympanic temperature (Tty) is lower than esophageal temperature (Tes). In experiment I the head heat loss was measured with and without headgear. Each of four subjects took part in three sessions of exercise on a cycle ergometer. The face was cooled to simulate outdoor conditions. The first session (no headgear) served as control for the two following sessions in which a headband and a woolen cap were worn. Evaporative and radiative-convective heat loss were monitored from the head. Wearing a cap significantly reduced the heat loss from the head compared with the control condition. During the headband session the heat loss was not significantly lower than the control values. Tty, Tes, and head skin temperatures (T(sk)) were also recorded. Tty was significantly lower (-0.55 +/- 0.15 degrees C) than Tes at the end of exercise (150-W exercise load) when no headgear was worn. During headgear sessions, Tty was no longer significantly lower than Tes, either during the headband (-0.15 +/- 0.31 degrees C) or during the cap session (-0.30 +/- 0.13 degrees C). In experiment II the influence of wearing headgear on temperature regulation was studied. Hand skin blood flow, hand T(sk), and heat loss from the hand were recorded in addition to the variables monitored in experiment I. Wearing headgear elevated Tty and peripheral vasomotor responses, whereas Tes evolved in the opposite direction.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychophysiological analysis of the anxiety model of bulimia nervosa

The anxiety model of bulimia nervosa was tested, using psychophysiological assessment of sympathetic arousal following eating. The experimental design included four groups-bulimia nervosa, obese, normals, and a normal control group who did not eat-assessed prior to and 60 min after eating. Five psychophysiological responses were measured throughout the session: heart rate, peripheral vasomotor response, skin temperature, skin resistance, and forearm electromyogram (EMG). Results produced mixed support for the anxiety model. Heart rate and EMG were both elevated for bulimics after eating. Other responses yielded patterns inconsistent with predictions from the anxiety model. These findings were discussed in terms of the utility of psychophysiological methods, relative to other approaches, for evaluating the anxiety model of bulimia nervosa. Suggestions for future studies in this area of research were also provided.

A three-dimensional finite-difference thermoregulatory model of a squirrel monkey

A three-dimensional thermoregulatory model of a squirrel monkey, whose shape is approximated by 742 rectangular blocks of varying sizes, has been developed. The inhomogeneous model has four layers: a core, a composite layer of muscle and fat, skin, and fur. The model simulates the flow of heat into and out of the body, including internal heat generation (metabolism) by the body, cooling and distribution of heat by blood, thermal conduction throughout the body, evaporative heat loss from sweating, and radiation and convection from the outer surface of the body. It also simulates dynamic thermoregulatory behavior such as peripheral vasomotor responses (skin vasodilation and vasoconstriction) and variable sweating rates. Computed results are compared with available experimental data; the agreement is good, especially for ambient temperatures above 26°C.

Reflex vascular responses in the finger to contralateral thermal stimuli during the normal menstrual cycle: a hormonal basis to Raynaud's phenomenon?

1. Raynaud's phenomenon is a condition which primarily affects women and it must be assumed that hormonal influences are responsible. 2. To further investigate this assumption the effect of cyclic sex hormone fluctuations on the digital vascular reactivity of ten normal young women was studied by the diagnostic techniques of thermal entrainment of finger blood flow and Doppler ultrasound mapping of the digital arteries. 3. In the immediate pre-ovulatory period the results obtained were comparable with those found in patients with established Raynaud's phenomenon, suggesting that oestrogen has an important modulating effect in vivo on reflex peripheral vasomotor responses to thermal stimuli. 4. 'Primary' Raynaud's phenomenon may represent an exaggerated response to oestrogen.

State-trait anxiety and biofeedback mediated control of peripheral vasomotor responses.

42 undergraduates completed the State-Trait Anxiety Inventory and then received biofeedback for increases in index finger-skin temperature. Subjects with high-trait anxiety increased their temperature significantly more than subjects with low-trait anxiety. No significant differences were found among state anxiety groups. The results supported the conclusion that predisposition to anxiety (trait), and not situational (state) anxiety, improves peripheral vasomotor control.

血管運動反応の道具的変容

The present paper deals with the development of the simple-sentence processing in Japanese children. Subjects were 2-, 3-, 4- and 5-year-olds. Experiment I exemplified the hypothesis that in children's processing of the simple sentence there is some span with the phrase as a unit. This was found to develop in parallel with the increase of short-term memory span for words, being about one unit larger than the latter at all age levels. Although sentence length is dominant, structural differences in the sentence of the same length was found to have some effects on the processing in Experiment II. The sentence itself becomes a chunk as early as the age of three.

Instrumental control of peripheral vasomotor responses in children.

ABSTRACTIn two experiments children acquired instrumental control over skin temperature with the aid visual feedback. In Experiment 1,3 out of 4 children learned to control the temperature difference their two hands. In Experiment 2. one of these children acquired significant control of the difference between two fingers of one hand. Such highly specific responses apparently reflect direct instrumental modification of the vasomotor system since generalized effects due to muscular tension or respiration could he ruled out.

Peripheral skin temperature and vasomotor responses during hypnotic induction

Abstract The present study is a further investigation of the hypothesis proposed by Reid and Curtsinger (1968) that hypnosis involves changes in peripheral vasomotor responses and skin temperature. 20 male Ss, screened for hypnotic susceptibility, participated in 2 experimental sessions. Each S was hypnotized in 1 session and simply given instructions to relax in the other session. Peripheral skin temperature and pulse volume were continuously monitored through-out each session. The resulting data were analyzed to determine the effects of hypnosis on these physiological measures. Under both conditions, a tendency for increased skin temperature and increased vasodilation was found. It was concluded that neutral hypnosis does not involve changes in these measures which are appreciably different from the changes associated with relaxation.