Peripheral circulation in the hand during natural ontogeny and under the conditions of prolonged graded traction

On the basis of the data of rheovasography (RVG) and laser Doppler flowmetry, comparative analysis of age-related changes in the peripheral blood circulation in hand tissues has been performed in 36 apparently healthy subjects aged 4–30 years and in 19 patients aged 18–50 years under the conditions of prolonged traction during surgical lengthening of finger bone stumps. The age-related changes in RVG are characterized by a higher volumetric blood content of tissues in children and adolescents, a decrease in the peripheral vascular tone, and wavelike recovery of capillary blood flow during reactive hyperemia, which is evidence for an unstable capillary tone. The dynamics of RVG indices during graded stretching in vivo (distraction) shows the dominance of an enhanced peripheral tone of arterioles and venules, and the response of the hand skin capillary bed to a 3-min ischemic test is analogous to the dynamics of indices of capillary blood flow in the hand skin of children.     

Leg blood flow during submaximal cycle ergometry is not reduced in healthy older normally active men.

The purpose of the present study was to test the hypothesis that leg blood flow responses during submaximal cycle ergometry are reduced with age in healthy normally active men. Eleven younger (20-25 yr) and eight older (62-73 yr) normotensive, nonendurance-trained men performed both graded and constant-load bouts of leg cycling at the same absolute and relative [% of peak O(2) consumption (Vo(2 peak))] exercise intensities while leg blood flow (femoral vein thermodilution), mean arterial pressure (MAP; radial artery), cardiac output (acetylene rebreathing), blood O(2) content, and plasma catecholamines were measured. Leg blood flow responses at the same absolute submaximal power outputs (20-100 W) and at a fixed systemic O(2) demand (1.1 l/min) did not differ between groups (P = 0.14-0.19), despite lower absolute levels of cardiac output in the older men (P < 0.05). MAP at the same absolute power outputs was 8-12 mmHg higher (P < 0.05) in the older men, but calculated leg vascular conductance responses (leg blood flow/MAP) were identical in the two groups (P > 0.9). At the same relative intensity (60% Vo(2 peak)), leg norepinephrine spillover rates were approximately twofold higher in the older men (P = 0.38). Exercise-induced increases in leg arterial-venous O(2) difference were identical between groups (P > 0.9) because both arterial and venous O(2) contents were lower in the older vs. younger men. These results suggest that the ability to augment active limb blood flow and O(2) extraction during submaximal large muscle mass exercise is not impaired but is well preserved with age in healthy men who are normally active.     

Aging and the skin blood flow response to the unloading of baroreceptors during heat and cold stress.

Control of skin blood flow (SkBF) is on the efferent arm of both thermoregulatory and nonthermoregulatory reflexes. To what extent aging may affect the SkBF response when these two reflex systems interact is unknown. To determine the response of aged skin to the unloading of baroreceptors in thermoneutral, cold stress, and heat stress conditions, sequential bouts of nonhypotensive lower body negative pressure (LBNP) were applied at -10, -20, and -30 mmHg in 14 young (18-25 yr) and 14 older (63-78 yr) men. SkBF was measured by laser-Doppler velocimetry (averaged over 2 forearm sites), and data are expressed as percentage of maximal cutaneous vascular conductance (%CVC(max)). Total forearm blood flow was measured by venous occlusion plethysmography, and forearm vascular conductance (FVC) was calculated as the ratio of forearm blood flow to mean arterial pressure. In young men, all three intensities of LBNP in thermoneutrality decreased FVC significantly (P < 0.05), but FVC at -10 mmHg did not change in the older men. There were no significant LBNP effects on %CVC(max). Application of LBNP during cold stress did not significantly change %CVC(max) or FVC in either age group. During heat stress, -10 to -30 mmHg of LBNP decreased FVC significantly (P < 0.05) in both age groups, but these decreases were attenuated in the older men (P < 0.05). %CVC(max) decreased at -30 mmHg in the younger men only. These results suggest that older men have an attenuated skin vasoconstrictor response to the unloading of baroreceptors in heat stress conditions. Furthermore, the forearm vasoconstriction elicited by LBNP in older men reflects that of underlying tissue (i.e., muscle) rather than that of skin, whereas -30 mmHg LBNP also decreases SkBF in young hyperthermic men.     

Differences in finger skin contact cooling response between an arterial occlusion and a vasodilated condition.

To assess the presence and magnitude of the effect of skin blood flow on finger skin cooling on contact with cold objects against the background of circulatory disorder risks in occupational exposures, this study investigates the effect of zero vs. close-to-maximal hand blood flow on short-term (< or =180 s) skin contact cooling response at a contact pressure that allows capillary perfusion of the distal pulp of the fingertip. Six male volunteers touched a block of aluminium with a finger contact force of 0.5 N at a temperature of -2 degrees C under a vasodilated and an occluded condition. Before both conditions, participants were required to exercise in a hot room for > or = 30 min for cutaneous vasodilation to occur (increase in rectal temperature of 1 degrees C). Under the vasodilated condition, forearm blood flow rate rose as high as 16.8 ml.100 ml(-1).min(-1). Under the occluded condition, the arm was exsanguinated, after which a blood pressure cuff was secured on the wrist inducing arterial occlusion. Contact temperature of the finger pad during the subsequent cold contact exposure was measured. No significant difference was found between the starting skin temperatures for the two blood flow conditions, but a distinct difference in shape of the contact cooling curve was apparent between the two blood flow conditions, with Newtonian cooling observed under the occluded condition, whereas a rewarming of the finger skin toward the end of the exposure occurred for the vasodilated condition. Blood flow was found to significantly increase contact temperature from 40 s onward (P < 0.01). It is concluded that, at a finger contact force compatible with capillary perfusion of the finger pad ( approximately 0.5 N), circulating blood provides a heat input source that significantly affects finger skin contact cooling during a vasodilated state.     

Cardiovascular reactions to cold exposures differ with age and gender

This study was conducted since virtually no information was available concerning age- and gender-related differences in cardiovascular adjustments to cold exposure. Men and women between the ages of 20 and 30 and 51 and 72 yr, wearing swim suits, rested for 2 h in 28, 20, 15, and 10 degrees C ambient temperatures (Ta), with 40% relative humidity. Cardiac output (Qc) and stroke volumes (Qs) were higher in younger than older subjects regardless of Ta. Cardiac output was not influenced by gender, but all cold exposures resulted in increased Qs and decreased heart rate in men but not women. Regardless of age or gender, Qc increased about 10% only during exposure to 10 degrees C. Cold exposure resulted in minimal increases in the mean systolic and diastolic pressures (Pa) of the younger subjects. The Pa of older subjects were higher than in the young during 28 degrees C exposures and increased during all cold exposures. Total peripheral resistance and forearm blood flows were higher in older than young subjects exposed to cold. Total peripheral resistance, systolic and diastolic Pa, and finger and forearm blood flows were not affected by gender, but hand plus forearm blood flows were higher in men than women exposed to 28 degrees C. Although Qc appeared adequate to meet increased oxygen demands of shivering in the older subjects, rising Pa may become limiting in extended exposures. A similar response in hypertensive or angina-prone individuals may result in some untoward responses.     

Effects of endogenous angiotensin II on the fetal circulation

The role of endogenous angiotensin II in the regulation of the circulation was investigated by infusion of [sar1],[ala8]-angiotensin II, a competitive antagonist of angiotensin II, into fetal sheep with chronically-maintained intravascular catheters. The thesis considered was that angiotensin II may have a greater role in the fetus than in the adult since the autonomic nervous system does not develop fully until late in gestation. Fetal cardiac output and its distribution to various organs and actual blood flows to fetal tissues were determined by the radionuclide-labelled microsphere technique. Intravenous infusion of [sar1], [ala8]-angiotensin II at a rate of 13.95-42.15 microgram/min per kg fetal body weight increased plasma renin activity from a control value of 8.9 +/- 1.6 to 18.9 +/- 3.9 ng/ml per h (SEM). Mean arterial blood pressure fell significantly from a control level of 47 +/- 1.6 to 41 +/- 1.1 mmHg. Blood flow to the unbilical-placental circulation decreased from 239 +/- 27.0 to 198 +/- 20.2 ml/min per kg, but the calculated vascular resistance in the umbilical-placental circulation did not change. Although cardiac output did not change, blood flow to the peripheral circulation, which includes the fetal skin, muscle and and bone and constitutes 75 +/- 0.9% of the total fetal body weight, increased as did flow to the thyroid and adrenal circulations. Endogenous angiotensin II appears to be important in maintaining blood flow to the umbilical-placental circulation by maintaining fetal arterial blood pressure. Angiotensin II exerts this effect by mediating a tonic vasoconstriction primarily in the peripheral circulation.     

Enhanced endothelin-1-mediated leg vascular tone in healthy older subjects.

Advanced age is associated with a decreased leg blood flow and reduced physical activity. Endothelin (ET-1), a powerful vasoconstrictor, may play a role in the increased leg vascular tone in older men. objectives: to assess the ET-1-mediated vascular tone in the legs of healthy sedentary older men, both before and after 8 wk of exercise training. methods: in 8 younger subjects (19-50 yr) and 8 older men (67-76 yr), bilateral leg blood flow was measured using venous occlusion plethysmography before and after antagonizing ET-1 (using selective ET(A/B)-receptor antagonists). In older men, reversibility of the observations was assessed after 8 wk of cycling. results: ET-receptor inhibition increased leg blood flow significantly more in older men compared with younger individuals (29 +/- 9% and 10 +/- 4%, respectively, P < 0.05). Eight-week cycling training increased baseline blood flow in older men. The blood flow response to ET-receptor inhibition in older men was not affected by the training program (25 +/- 8%, P > 0.05 for comparison with pretraining). The flow ratio (blood flows infused leg/noninfused leg) decreased significantly by training from 26 +/- 8% to 7+3% (P < 0.05). CONCLUSION: the increased baseline vascular tone in aging is at least in part mediated by the endothelin. Eight-weeks cycling training in older sedentary men decreased leg vascular tone and seems to partly decrease the ET-1-mediated vascular tone.     

Functional Status of Cerebral and Antebrachial Circulation in Five- to Nine-Year-Old Children

Cerebral and peripheral circulation in 200 five- to seven-year-old children was studied with focused and tetrapolar impedance plethysmography. The strongest changes in the cerebral blood flow (CBF) were found to occur during the sixth year, whereas an increase in the tonic tension in large cerebral arteries takes place by the end of the ninth year. Significant alterations in the arterial tone and in volumetric velocity of the blood flow (VVBF) in the forearm were observed at the age of six, seven, and nine years. In five- to nine-year-old children, a local static workload significantly decreased CBF, increased the tone of large cerebral arteries, and caused a long-lasting increase in the antebrachial vascular tone accompanied by an exercise hyperemia which was more intense in nine-year-old children, whereas cerebral circulation reactivity was stronger in the younger group.     

Seroepidemiology of Helicobacter pylori infection in Greece

Helicobacter pylori infection is strongly associated with chronic gastritis and peptic ulceration. As the prevalence of H. pylori infection in southern European populations is not known, a serological survey of 1069 samples from three different age groups in the Greek population was carried out with an enzyme-linked immunosorbent assay (ELISA) for antibodies to these bacteria. The antigen was an ultracentrifuged supernate of whole cell sonicates of 5 isolates of H. pylori assessed by electrophoresis and by immunoblotting with negative and positive sera. The sensitivity of the test was 97.43% and the specificity 100% for IgG antibodies; IgA and IgM antibodies to the antigen preparation were not found. Antibodies to H. pylori were detected among 39.4% of children aged 1-10 years, 67.1% of recruits (20-27 years) and 70% of blood donors (20-50 years). The prevalence of antibodies did not differ with sex in each of the age groups. The proportion of individuals with antibodies to H. pylori was higher in the younger age groups than those reported for similar age groups in western Europe.     

Seroepidemiology of Helicobacter pylori infection in Greece

Abstract Helicobacter pylori infection is strongly associated with chronic gastritis and peptic ulceration. As the prevalence of H. pylrori infection in southern European populations is not known, a serological survey of 1069 samples from three different age groups in the Greek population was carried out with an enzyme-linked immunosorbent assay (ELISA) for antibodies to these bacteria. The antigen was an ultracentrifuged supernate of whole cell sonicates of 5 isolates of H. pylori assessed by electrophoresis and by immunoblotting with negative and positive sera. The sensitivity of the test was 97.43% and the specificity 100% for IgG antibodies; IgA and IgM antibodies to the antigen preparation were not found. Antibodies to H. pylori were detected among 39.49% of children aged 1–10 years, 67.1% of recruits (20–27 years) and 70% of blood donors (20–50 years). The prevalence of antibodies did not differ iwth sex in each of the age groups. The proportion of individuals with antibodies to H. pylori was higher in the younger age groups than those reported for similar age groups in Western Europe.     

Muscle pump does not enhance blood flow in exercising skeletal muscle.

The muscle pump theory holds that contraction aids muscle perfusion by emptying the venous circulation, which lowers venous pressure during relaxation and increases the pressure gradient across the muscle. We reasoned that the influence of a reduction in venous pressure could be determined after maximal pharmacological vasodilation, in which the changes in vascular tone would be minimized. Mongrel dogs (n = 7), instrumented for measurement of hindlimb blood flow, ran on a treadmill during continuous intra-arterial infusion of saline or adenosine (15-35 mg/min). Adenosine infusion was initiated at rest to achieve the highest blood flow possible. Peak hindlimb blood flow during exercise increased from baseline by 438 +/- 34 ml/min under saline conditions but decreased by 27 +/- 18 ml/min during adenosine infusion. The absence of an increase in blood flow in the vasodilated limb indicates that any change in venous pressure elicited by the muscle pump was not adequate to elevate hindlimb blood flow. The implication of this finding is that the hyperemic response to exercise is primarily attributable to vasodilation in the skeletal muscle vasculature.     

Peripheral blood flow in menopausal women who have hot flushes and in those who do not.

OBJECTIVE--To compare blood pressure, heart rate, and peripheral vascular responsiveness in menopausal women who have hot flushes and in those who do not, and to assess the effect on these variables of treating women who have hot flushes with oestriol, a natural oestrogen, given vaginally. DESIGN--An open, non-randomised cohort study of flushing and non-flushing menopausal women. A before and after investigation of the effects of vaginal oestriol treatment on the circulation. SETTING--Referral based endocrinology clinic. PATIENTS--88 Consecutive menopausal women, 63 complaining of frequent hot flushes and 25 who had not flushed for at least a year. INTERVENTION--Treatment with vaginal oestriol 0.5 mg at night for six weeks in 18 of the women who had hot flushes. MEASUREMENTS AND MAIN RESULTS--Peripheral blood flow was measured by venous occlusion plethysmography at rest and in response to stressful mental arithmetic and anoxic forearm exercises. Blood flow in the forearm and its variability were significantly higher in flushing than in non-flushing women (4.1 (SD 1.7) and 3.1 (0.9) ml/100 ml tissue/min and 17% and 13% respectively). Blood pressure, heart rate, and blood flow in the hand were, however, similar in the two groups. No difference was found in the peripheral incremental response to either stress or anoxic exercise. Vaginal oestriol significantly lowered forearm blood flow from 4.4 (1.5) to 3.3 (1.1) ml/100 ml tissue/min but dilator responsiveness was unaffected. CONCLUSIONS--The peripheral circulation is different in menopausal women who have hot flushes compared with those who do not, with selective vasodilatation in the forearm. The lowered blood flow in the forearm after vaginal oestriol in flushing women may be relevant to the alleviation of vasomotor symptoms induced by oestrogen treatment.     

Regional blood flows and cardiac hemodynamics in renovascular and mineralocorticoid hypertensive rats

Regional blood flows and cardiac hemodynamics were studied in 3 models of hypertensive rats: one-kidney DOC-saline, one-kidney, one-clip and two-kidney, one-clip hypertension and in normotensive control rats. All hypertensive models were characterized by increased peripheral vascular resistance and normal cardiac output. Coronary and cerebral blood flows varied among the hypertensive models but did not significantly differ from the normotensive rats. However, coronary blood flow of one-kidney, one-clip rats (8.4 +/- 1.3 ml X min-1 X g-1) was significantly higher than that of the two-kidney one-clip rats (6.5 +/- 1.2 ml X min.-1 X g-1, P less than 0.05). Cerebral blood flow of DOC-saline rats was lower than that of two-kidney one-clip or one-kidney one-clip renovascular rats. Renal blood flows of the unclipped kidney of two-kidney renovascular rats (3.77 +/- 0.85 ml X min-1 X g-1) and DOC-saline rats (2.95 +/- 0.83 ml X min-1 X g-1) were significantly lower than those of normotensive rats (5.92 +/- 1.16 ml X min-1 X g-1, P less than 0.05). In conclusion, although vascular resistance becomes elevated in all models of experimental hypertension, regional vascular resistance and blood flow distribution may differ depending on the vasoconstrictor mechanisms that participate in each model.     

Influences of age and gender on human thermoregulatory responses to cold exposures

To delineate age- and gender-related differences in physiological responses to cold exposure, men and women between the ages of 20 and 29 yr and 51 and 72 yr, wearing minimal clothing, were exposed at rest for 2 h to 28, 20, 15, and 10 degrees C room temperatures with 40% relative humidity. During the coldest exposure, the rates of increase in metabolic rate (W X m-2 or ml X kg lean body mass-1 X min-1 were similar for all groups. However, older women (n = 7) may have benefited from a larger (P less than 0.05) early metabolic (M) increase (40% within 15 min) than young men (18%) (n = 10), young women (5%) (n = 10), or older men (5%) (n = 10). A similar rapid M response in older women occurred during the 15 degrees C exposure. During all cold exposures, older women maintained constant rectal temperature (Tre) and young women maintained Tre only during the 20 degrees C exposures, whereas Tre of the men declined during all cold exposures (P less than 0.01). Changes in Tre and mean skin temperature (Ts) during cold exposure were largely related to body fat, although age and surface area/mass modified the changes in men. The data suggest that older men are more susceptible to cold ambients than younger people, since they did not prevent a further decline in their initially relatively low Tre. Despite greater insulation from body fat, the older women maintained a constant Tre at greater metabolic cost than men or younger women.     

Increased lipolysis but diminished gene expression of lipases in subcutaneous adipose tissue of healthy young males with intrauterine growth retardation

Intrauterine growth retardation (IUGR) is associated with a central fat distribution and risk of developing type 2 diabetes in adults when exposed to a sedentary Western lifestyle. Increased lipolysis is an early defect of metabolism in IUGR subjects, but the sites and molecular mechanisms involved are unknown. Twenty IUGR and 20 control (CON) subjects, aged 20-30 years, were studied before and after 10 days of bed rest using the glucose clamp technique combined with measurements of in vivo metabolism by microdialysis technique and blood flow by (133)Xe washout technique in subcutaneous abdominal (SCAAT) and femoral (SCFAT) adipose tissue. Additionally, mRNA expression of lipases was evaluated in biopsies from SCAAT. Lipolysis in SCAAT was substantially higher in IUGR than in CON subjects despite markedly lower mRNA expression of lipases. Blood flow was higher in IUGR compared with CON in both SCAAT and SCFAT. Whole body insulin sensitivity did not differ between groups and decreased after bed rest. After bed rest, SCAAT lipolysis remained higher in IUGR compared with CON, and SCFAT lipolysis decreased in CON but not in IUGR. Prior to the development of whole body insulin resistance, young men with IUGR are characterized by increased in vivo adipose tissue lipolysis and blood flow with a paradoxically decreased expression of lipases compared with CON, and 10 days of physical inactivity underlined the baseline findings. Subjects with IUGR exhibit primary defects in adipose tissue metabolism.     

Isoxsuprine as an oral vasodilator

The effect of isoxsuprine, administered orally as a single 20-mg tablet, was compared with that of a placebo in a double-blind crossover study in 12 volunteers with and in 12 without peripheral vascular disease. Isoxsuprine failed to increase blood flow in the calf, foot or hand, and did not alter blood pressure or heart rate significantly. Claudication time was not prolonged after taking the drug. This study does not support the value of oral administration of isoxsuprine as a peripheral vasodilator.     

Age and sex dependence of hemodynamic parameters of human internal carotid arteries

The study of the ultrasound diameter, linear velocity, and resistance of the internal carotid arteries in 647 subjects of both sexes aged from 1 to 74 years has been performed. Additionally, shear stress and the Reynolds number have been calculated. During the period from early childhood to adolescence and from the first mature to younger elderly ages, there is an increase in the diameter of the internal carotid arteries. Phases of an increase in the vascular resistance by the first period of childhood, adolescence, and younger elderly age are observed. The space flow velocity has relatively stable parameters till youth, and then it declines by younger elderly age. The average linear velocity, shear stress, and the Reynolds number progressively diminish twice by younger elderly age. Laminar blood flow with local twists in the early stages of postnatal ontogenesis is characteristic of the internal carotid arteries. The diameter of the internal carotid arteries, vascular resistance index, and blood flow velocity are higher in men than in women during most age periods. Shear stress in both internal carotid arteries during all the age periods studied is symmetrical and has no sex differences.     

Ultradian rhythmic models of blood pressure variation in normal human daily life

To examine levels and variance structure of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR), we measured those 3 variables every 7.5 min for 24 h (approximately 192 samples each subject) by ambulatory monitoring in 2 nominated groups of normal volunteers: younger (Y; 8 men, 5 women, 24-44 years) and older (O; 13 men, 12 women, 50-95 years). Y and O did not differ in either sleep or wake means for HR and DBP. Mean SBP in O was 17 mm Hg higher than in Y during wakefulness. Thirty-four subjects had significant low frequency variations (presumably the circadian rhythm) in SBP, DBP and HR, regardless of age. A periodic model fitting the time series required a 9 h feature (rhythm) for Y and O in DBP for best reduction of mean square error. In addition, O regularly showed 3 h features in both SBP and DBP, a 6 h feature in DBP and a 9 h feature in SBP, which were absent in Y. Our results suggest that low-power ultradian rhythms may appear in both SBP and DBP after age 50, and possibly serve as dynamic markers of normal cardiovascular aging.     

Cutaneous microcirculation in systemic sclerosis and response to intra-arterial reserpine.

The cutaneous microcirculation in the hand was measured in 23 patients with systemic sclerosis, 19 with Raynaud''s phenomenon and four without Raynaud''s phenomenon, and 20 controls. The patients with Raynaud''s phenomenon had a reduced basal blood flow and an exaggerated further reduction on local cold stimulation, though both were normal in patients without Raynaud''s phenomenon. Reflex-induced vascular changes by cold stimulation of the contralateral hand showed no differences between the three groups. The blood flows were similar in the affected skin of the anterior chest wall in four patients with systemic sclerosis and peripheral Raynaud''s phenomenon and matched controls. In the seven most severely affected patients 1 mg of intra-arterial reserpine produced a prompt improvement in the cutaneous microcirculation which usually lasted one to three weeks but occasionally much longer. By judicious use of repeated injection guided by measurements of the microcirculation it was possible to heal indolent ulcers of the fingers. The results indicate that vascular changes are common in systemic sclerosis but are not fundamental in the pathogenesis of the disease. More probably there is a general soft tissue abnormality that usually but not necessarily affects the vessels.