Law Enforcement Officers Have an Increased Prevalence of Subclinical Cardiovascular Disease That Is Not Explained by Traditional Risk Factors.

The aim of the study is to determine if law enforcement officers develop subclinical atherosclerotic cardiovascular disease (ASCVD) earlier than nonofficers and, if so, the extent to which conventional risk factors explain this difference. Methods: Estimated pulse wave velocity (ePWV) was the marker of subclinical ASCVD. EPWV, ASCVD risk factors, metabolic syndrome (MetS), and 10-year risk for ASCVD were compared among 408 law enforcement officers and a civilian cohort.

Angiotensin II type 2 receptor-mediated dilation is greater in the cutaneous microvasculature of premenopausal women compared with men.

Differential activation of the renin-angiotensin system (RAS) likely contributes to sex differences in cardiovascular outcomes in premenopausal women compared with age-matched men. Women demonstrate reduced activation of the vasoconstrictor angiotensin II type 1 receptors (ATR) compared with men, and evidence suggests that women also likely have increased sensitivity of the vasodilatory angiotensin II type 2 receptors (ATR). However, few in vivo studies have directly examined sex differences in ATR-mediated dilation, or the balance between ATR- and ATR-mediated vascular responses in humans.

Chronic intermittent hypoxia promotes glomerular hyperfiltration and potentiates hypoxia-evoked decreases in renal perfusion and PO.

Sleep apnea (SA) is highly prevalent in patients with chronic kidney disease and may contribute to the development and/or progression of this condition. Previous studies suggest that dysregulation of renal hemodynamics and oxygen flux may play a key role in this process. The present study sought to determine how chronic intermittent hypoxia (CIH) associated with SA affects regulation of renal artery blood flow (RBF), renal microcirculatory perfusion (RP), glomerular filtration rate (GFR), and cortical and medullary tissue PO as well as expression of genes that could contribute to renal injury.

Remote ischaemic preconditioning - translating cardiovascular benefits to humans.

Remote ischaemic preconditioning (RIPC), induced by intermittent periods of limb ischaemia and reperfusion, confers cardiac and vascular protection from subsequent ischaemia-reperfusion (IR) injury. Early animal studies reliably demonstrate that RIPC attenuated infarct size and preserved cardiac tissue. However, translating these adaptations to clinical practice in humans has been challenging.

Delayed Cutaneous Microvascular Responses With Non-consecutive 3 Days of Remote Ischemic Preconditioning.

The optimal frequency and duration of remote ischemic preconditioning (RIPC) that augments microvascular function is unknown. A single bout of RIPC increases cutaneous endothelial function for ∼48 h, whereas 1 week of daily RIPC bouts improves more sustained endothelium-independent function. We hypothesized that 3 days of RIPC separated by rest days (3QOD RIPC) would result in sustained increases in both endothelium-dependent and endothelium-independent functions.

Laser speckle contrast imaging and laser Doppler flowmetry reproducibly assess reflex cutaneous vasoconstriction.

Objective: Reproducibility of the reflex cutaneous vasoconstriction response is currently unknown. Our aim was to determine the test-retest reproducibility of laser speckle contrast imaging (LSCI) and varying sampling depths of laser Doppler flowmetry (LDF) in response to whole-body cooling.

Methods: Over two studies, nine and fourteen healthy, young adults underwent a 40-min cooling bout over two separate experiments.

Delayed window of improvements in skin microvascular function following a single bout of remote ischaemic preconditioning.

New Findings: What is the central question of this study? Animal infarct studies indicate a delayed window of cardiac protection after remote ischaemic preconditioning (RIPC); however, the presence and duration of this delayed effect have not been examined in human microvasculature in vivo. What is the main finding and its importance? Cutaneous vasodilatation induced by local heating or ACh was increased significantly 24 and 48 h after a single bout of RIPC, respectively. Neither response persisted beyond ∼48 h.

Reproducibility and normalization of reactive hyperemia using laser speckle contrast imaging.

Background: Impaired perfusion indices signal potential microvascular dysfunction preceding atherosclerosis and other cardiometabolic pathologies. Post-occlusive reactive hyperemia (PORH), a vasodilatory response following a mechanically induced ischemia, is a transient increase in perfusion and can assess microvascular function. The greatest blood flow change corresponding to the first minute of hyperemia (represented by time-to-peak, hyperemic velocity, AUC within 1st min) has been shown to indicate microvascular dysfunction.

Baroreflex function in Parkinson's disease: insights from the modified-Oxford technique.

Nonmotor symptoms are common in Parkinson's disease (PD) and they include dysregulation of cardiovascular system, which adversely affects quality of life. Recent studies provide indirect evidence that baroreflex dysfunction may be one of the mechanisms of cardiovascular dysregulation in PD. Herein, we tested the hypothesis that the baroreflex gain, assessed across an extensive range of the reflex arc by eliciting rapid changes in blood pressure (BP) induced by sequential boluses of vasoactive drugs (modified-Oxford technique) would be attenuated in middle-aged patients with PD.

Two weeks of remote ischaemic preconditioning alters sympathovagal balance in healthy humans.

New Findings: What is the central question of this study? Delayed cardiovascular responses occur following a single bout of remote ischaemic preconditioning (RIPC). Is heart rate variability (HRV), a surrogate marker of cardiac vagal control, able to detect a delayed effect after a single bout of RIPC? Do repeated bouts of RIPC further alter HRV? What is the main finding and its importance? Indices of HRV indicated a shift in sympathovagal balance toward greater parasympathetic activity following 2 weeks of RIPC but not after a single bout of RIPC. Thus, repeated bouts of RIPC were necessary to elicit changes in autonomic function.

Cardiorespiratory Fitness and Muscular Strength on Arterial Stiffness in Older Adults.

Purpose: To evaluate the independent and combined associations of cardiorespiratory fitness (CRF) and muscular strength (MS) with arterial stiffness (AS), a strong predictor of cardiovascular disease, in older adults.

Methods: This cross-sectional study included 405 older adults (mean age, 72 yr). Cardiorespiratory fitness was assessed by time (s) to complete a 400-m walking test and MS by maximal handgrip strength (kg).

Improved endothelial-dependent and endothelial-independent skin vasodilator responses following remote ischemic preconditioning.

One week of daily remote ischemic preconditioning (RIPC) improves cutaneous vasodilatory (VD) function. However, the underlying mechanisms and the number of sessions needed to optimize this adaptive response remain unclear. We hypothesized that the responses to localized heating of the skin will be greater after 2 wk as opposed to 1 wk of RIPC.

Oral L-Tyrosine Supplementation Improves Core Temperature Maintenance in Older Adults.

Introduction: During cold exposure, an increase in sympathetic nerve activity evokes vasoconstriction (VC) of cutaneous vessels to minimize heat loss. In older adults, this reflex VC response is impaired thereby increasing their susceptibility to excess heat loss and hypothermia. Because L-tyrosine, the amino acid substrate necessary for catecholamine production, has been shown to augment reflex VC in age skin, we hypothesize that oral ingestion of L-tyrosine will attenuate the decline in core temperature (Tc) during whole-body cooling in older adults.

Seven consecutive days of remote ischaemic preconditioning improves cutaneous vasodilatory capacity in young adults.

Key Points: Remote ischaemic preconditioning (RIPC), induced by brief bouts of ischaemia followed by reperfusion, confers vascular adaptations that protect against subsequent bouts of ischaemia; however, the effect of RIPC repeated over several days on the human microcirculation is unknown. Using skin as a model, microvascular function was assessed at a control and a NO-inhibited area of skin before 1 day after and 1 week after administering seven consecutive days of repeated RIPC on the contralateral arm. Maximal vasodilatation was increased by ∼20-50% following 7 days of repeated RIPC, and this response remained elevated 1 week after stopping RIPC; however, NO-mediated vasodilatation was not affected by the RIPC stimulus.

Age-related differences in the cutaneous vascular response to exogenous angiotensin II.

Angiotensin II (ANG II) is locally produced in human skin and contributes to the reflex vasoconstriction (VC) response in aged but not young skin. We hypothesized that the exogenous ANG II-mediated VC response would be greater in older adults and would be affected by inhibition of adrenoreceptor or ANG II type II receptor (ATR) pathways. Three microdialysis (MD) fibers were placed in the forearm skin of 11 young (26 ± 3 yr) and 11 older (68 ± 4 yr) individuals for perfusion of 1) Ringer solution (control), 2) adrenoreceptor blockade with yohimbine + propranolol, and 3) ATR inhibition with PD-123319.

Effects of blood flow restricted exercise training on muscular strength and blood flow in older adults.

Background: In young adults, blood flow restricted exercise (BFRE) at relatively low intensities can increase muscle strength as effectively as conventional high intensity training. Ischemic exercise can also increase collateral blood flow in skeletal muscle. However, the effects of chronic BFRE on muscle strength and blood flow in older adults remain unknown.

Oral l-tyrosine supplementation augments the vasoconstriction response to whole-body cooling in older adults.

What is the central question of this study? Ageing is associated with altered sympathetic responses to stress, which are explained in part by reduced noradrenergic function. The impact of supplementation with oral l-tyrosine, the amino acid precursor for catecholamine synthesis, on the effector responses to cold and exercise stress has yet to be examined. What is the main finding and its importance? Oral l-tyrosine ingestion augmented the sympathetically mediated vasoconstriction response to cold exposure in aged skin.

Evidence for a functional vasoconstrictor role for ATP in the human cutaneous microvasculature.

What is the central question of this study? In young adults, about half of the cold-related reduction in skin blood flow during cold exposure is mediated by noradrenaline, while the remainder is attributable to other substances co-released with noradrenaline that have yet to be identified. What is the main finding and its importance? Purinergic receptor blockade blunted the vasoconstriction response to whole-body cooling and to intradermal administration of tyramine. These results indicate that ATP is necessary to vasoconstrict blood vessels in the skin adequately and prevent heat loss in a cold environment.

Angiotensin II type I receptor blockade attenuates reflex cutaneous vasoconstriction in aged but not young skin.

Stimulation of angiotensin II type I receptors (AT1R) elicits vasoconstriction (VC) that may be occurring through the activation of a pathogenic vascular pathway such as Rho kinase (ROCK). We hypothesize that reflex cutaneous VC to whole body cooling (mean skin temperature = 30.5°C) in older humans relies in part on AT1R activation, which may explain greater ROCK activity attendant with aging.

Increased brachial artery retrograde shear rate at exercise onset is abolished during prolonged cycling: role of thermoregulatory vasodilation.

Acute leg exercise increases brachial artery retrograde shear rate (SR), while chronic exercise improves vasomotor function. These combined observations are perplexing given the proatherogenic impacts of retrograde shear stress on the vascular endothelium and may be the result of brief protocols used to study acute exercise responses. Therefore, we hypothesized that brachial artery retrograde SR increases initially but subsequently decreases in magnitude during prolonged leg cycling.

Tetrahydrobiopterin does not affect end-organ responsiveness to norepinephrine-mediated vasoconstriction in aged skin.

We have recently demonstrated that tetrahydrobiopterin (BH(4)) augments reflex vasoconstriction (VC) in aged skin. Although this appears to occur through its role in norepinephrine (NE) biosynthesis, the extent with which vascular mechanisms are affected are unknown. We hypothesized that localized BH(4) supplementation would not affect the VC response to exogenous NE when sympathetic nerves were blocked.

Systemic low-dose aspirin and clopidogrel independently attenuate reflex cutaneous vasodilation in middle-aged humans.

Chronic systemic platelet cyclooxygenase (COX) inhibition with low-dose aspirin [acetylsalicylic acid (ASA)] significantly attenuates reflex cutaneous vasodilation in middle-aged humans, whereas acute, localized, nonisoform-specific inhibition of vascular COX with intradermal administration of ketorolac does not alter skin blood flow during hyperthermia. Taken together, these data suggest that platelets may be involved in reflex cutaneous vasodilation, and this response is inhibited with systemic pharmacological platelet inhibition. We hypothesized that, similar to ASA, specific platelet ADP receptor inhibition with clopidogrel would attenuate reflex vasodilation in middle-aged skin.