Rheumatoid arthritis and cardiovascular complications during delivery: a United States inpatient analysis.

BACKGROUND AND AIMS: Persons with rheumatoid arthritis (RA) have an increased risk of obstetric-associated complications, as well as long-term cardiovascular (CV) risk. Hence, the aim was to evaluate the association of RA with acute CV complications during delivery admissions. METHODS: Data from the National Inpatient Sample (2004-2019) were queried utilizing ICD-9 or ICD-10 codes to identify delivery hospitalizations and a diagnosis of RA. RESULTS: A total of 12 789 722 delivery hospitalizations were identified, of which 0.1% were among persons with RA (n = 11 979). Individuals with RA, vs. those without, were older (median 31 vs. 28 years, P < .01) and had a higher prevalence of chronic hypertension, chronic diabetes, gestational diabetes mellitus, obesity, and dyslipidaemia (P < .01). After adjustment for age, race/ethnicity, comorbidities, insurance, and income, RA remained an independent risk factor for peripartum CV complications including preeclampsia [adjusted odds ratio (aOR) 1.37 (95% confidence interval 1.27-1.47)], peripartum cardiomyopathy [aOR 2.10 (1.11-3.99)], and arrhythmias [aOR 2.00 (1.68-2.38)] compared with no RA. Likewise, the risk of acute kidney injury and venous thromboembolism was higher with RA. An overall increasing trend of obesity, gestational diabetes mellitus, and acute CV complications was also observed among individuals with RA from 2004-2019. For resource utilization, length of stay and cost of hospitalization were higher for deliveries among persons with RA. CONCLUSIONS: Pregnant persons with RA had higher risk of preeclampsia, peripartum cardiomyopathy, arrhythmias, acute kidney injury, and venous thromboembolism during delivery hospitalizations. Furthermore, cardiometabolic risk factors among pregnant individuals with RA rose over this 15-year period.

Real-World Experience of Tixagevimab and Cilgavimab (Evusheld) in Rheumatologic Patients on Rituximab.

BACKGROUND/OBJECTIVE: Although vaccination is the primary strategy against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), rheumatologic patients on B-cell depleting agent rituximab may have a suboptimal response. Tixagevimab and cilgavimab (Evusheld) could be administered under Food and Drug Administration emergency use authorization as pre-exposure prophylaxis. METHODS: A cohort study of rheumatologic patients on rituximab therapy who received Evusheld was followed longitudinally. Adverse events were monitored. RESULTS: Forty-three patients received Evusheld, with diagnoses including rheumatoid arthritis, ANCA vasculitis, immune-mediated myositis, Sjögren disease, and systemic lupus erythematosus. Average time to follow-up was 100 ± 33 days. One patient experienced symptomatic infection with SARS-CoV-2 confirmed by home antigen test twice. A total of 97.8% of patients during follow-up did not contract acute SARS-CoV-2 infection. At the same time, 32,074 new local cases were reported with a local cumulative SARS-CoV-2 incidence rate of 4.32%. Adverse events included myalgia, flu-like symptoms, fevers, injection site pain, or headache. No serious adverse events, anaphylaxis, or cardiac events occurred. CONCLUSIONS: Evusheld demonstrated effectiveness in preventing symptomatic SARS-CoV-2 infection in a real-world cohort of rheumatologic patients on rituximab therapy. Administration of Evusheld may be considered as part of a multilayered approach to risk mitigation in this high-risk population as pre-exposure prophylaxis.

Real-World Effectiveness of Tixagevimab and Cilgavimab (Evusheld) in Patients With Hematological Malignancies.

Background: Immunocompromised individuals with hematological malignancy have increased risk for poor outcomes and death from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This special population may mount a suboptimal response to vaccination. We assessed the effectiveness of tixagevimab and cilgavimab (Evusheld), a monoclonal antibody combination against SARS-CoV-2, in conjunction with standard preventative measures, at preventing symptomatic incident infection. Methods: Patients aged 18 years and older with hematological malignancy consented to receive Evusheld. Patients were followed longitudinally for development of symptomatic incident SARS-CoV-2 infections. Adverse events were monitored. Results: Two hundred and three patients (94 female) with hematological malignancies and mean age 72 ± 10 years were included. Of the patients, 99.5% had received at least one mRNA vaccination against SARS-CoV-2. Average time of follow-up was 151 ± 50 days. Nineteen patients (9.3%) developed incident symptomatic SARS-CoV-2 infection, with only one (0.5%) requiring hospitalization. During the same follow-up period, local incident rate of infection was 84,123 cases (11.3% of population). Of those, 3,386 cases (4%) of SARS-CoV-2 required hospital admission. The incidence rate ratio was 0.79. No serious adverse events occurred following administration of Evusheld. Conclusion: Patients with hematological malignancy who received Evusheld infrequently developed symptomatic infections or require hospitalization. The high-risk cohort incidence was at least as comparable to the average risk general population. Evusheld appears effective and is well tolerated, and may be administered in conjunction with vaccination and standard prevention measures, at decreasing incident SARS-Co-V2 cases in this high-risk population.

Severe cholestatic hyperbilirubinaemia secondary to thyrotoxicosis complicated with bile cast nephropathy treated with plasma exchange and haemodialysis.

Thyrotoxicosis rarely presents as cholestatic hyperbilirubinaemia, and severe bilirubin elevation may lead to bile cast nephropathy. We present a case of a young woman with newly diagnosed Graves' disease with thyrotoxicosis who developed severe hyperbilirubinaemia and bile cast nephropathy. Serial plasma exchange and temporary haemodialysis led to full renal recovery. After treatment of her thyrotoxicosis with antithyroid medication and radioactive iodine ablation, her bilirubin normalised.

Adult-onset Still's disease with haemorrhagic pericarditis and tamponade preceded by acute Lyme disease.

A 61-year-old Caucasian man presented with a fever of unknown origin, a transient erythematous rash on his right upper extremity and chest pressure after being treated for erythema migrans (Lyme disease). Echocardiogram demonstrated a large pericardial effusion with tamponade. He underwent pericardiostomy with tube placement. Workup for infectious and malignant etiologies was negative. Histology of the pericardium showed acute on chronic fibrinous haemorrhagic pericarditis. The patient met criteria for adult-onset Still's disease. Symptoms resolved following treatment with methylprednisolone and anakinra. We believe this is the first case of adult-onset Still's disease precipitated by acute Lyme disease.

Coeliac artery dissection as a rare manifestation of Behcet's disease.

Behcet's disease is a multisystemic vasculitis. Arterial involvement in the form of acute dissection is rare. A 42-year-old Lebanese man with Behcet's disease presented with severe abdominal pain. On exam, blood pressure was 162/104 mm Hg, and he exhibited epigastric tenderness. CT angiogram demonstrated an acute dissection of the coeliac artery trunk, common hepatic artery and proper hepatic arteries, with asymmetric thickening of the proximal left subclavian artery and circumferential thickening of the abdominal infrarenal aorta suggestive of vasculitis. Treatment included intravenous clevidipine, nitroprusside and methylprednisolone, which transitioned to oral metoprolol, amlodipine and prednisone. He responded well. Arterial dissections have been described with Behcet's. We report a coeliac artery aneurysm in association with a flare of Behcet's disease. Arterial wall inflammation combined with the sheering forces of hypertension likely predisposes to arterial dissection.

Prostatitis, a rare presentation of granulomatosis with polyangiitis, successfully treated with rituximab and prednisone.

A previously healthy 21-year-old man presented with an 8-month history of weight loss, lethargy and dysuria unresponsive to empiric antibiotics and paraurethral drainage of a prostatic abscess. Urinalysis showed pyuria, but cultures failed to grow any organisms. Additionally, he developed new onset sensorineural hearing loss. CT of the chest showed two right-sided cavitary lesions. CT of the abdomen and pelvis demonstrated a prostatic abscess. A prostate biopsy demonstrated necrotising granulomatous prostatitis. A lung biopsy showed necrotising granulomatous inflammation. He was diagnosed with granulomatosis with polyangiitis (GPA). He was successfully treated with rituximab and prednisone. At 6-month follow-up, he continued to be in remission with resolution of his symptoms. This case demonstrates a rare presentation of prostatitis as the presenting symptom of GPA. As far as we know, this case is the first documented report of rituximab and prednisone as successful therapy for prostatitis secondary to GPA.

Safe usage of anakinra and dexamethasone to treat refractory hemophagocytic lymphohistiocytosis secondary to acute disseminated histoplasmosis in a patient with HIV/AIDS.

Hemophagocytic lymphohistiocytosis (HLH) is a serious life-threatening disease if not recognised early. In patients with HIV/AIDS, this association has been reported following acute opportunistic infections, including histoplasmosis. However, optimal treatment is not known. We describe a male aged 46 years with AIDS who developed HLH following acute disseminated histoplasmosis. Presenting symptoms included fever, hepatosplenomegaly and pancytopenia. Bone marrow biopsy confirmed HLH. Initially, he was refractory to the treatment with amphotericin B, antiretroviral therapy and intravenous immunoglobulin (IVIG). Anakinra, an interleukin-1 receptor antagonist, and dexamethasone were initiated. He improved clinically, did not exhibit any harmful effects and ultimately was discharged from the hospital. This, we believe, is the first reported treatment of HLH with anakinra in a patient with AIDS and acute disseminated histoplasmosis.

A double-blind placebo-controlled cross-over study of the vascular effects of midodrine in neuropathic compared with hyperadrenergic postural tachycardia syndrome.

POTS (postural tachycardia syndrome) is a chronic form of OI (orthostatic intolerance). Neuropathic POTS is characterized by decreased adrenergic vasoconstriction, whereas hyperadrenergic POTS exhibits increased adrenergic vasoconstriction. We hypothesized that midodrine, an α1-adrenergic receptor agonist, would increase CVR (calf vascular resistance), decrease C(v) (calf venous capacitance) and decrease orthostatic tachycardia in neuropathic POTS, but not alter haemodynamics in hyperadrenergic POTS. A total of 20 POTS patients (12 neuropathic and eight hyperadrenergic), ages 12-20 years, participated in this randomized placebo-controlled double-blind cross-over study. Of these subjects, 15 were female. POTS subjects received 2 weeks of treatment with midodrine or placebo, with increased dosing from 2.5 to 10 mg three times daily. Following a 7-day drug-washout period, subjects received the cross-over treatment. HR (heart rate), MAP (mean arterial pressure), Q(calf) (calf blood flow) and CVR were measured supine and during 35° HUT (head-up tilt). C(v) was measured supine. In neuropathic POTS, midodrine decreased supine HR, Q(calf) and C(v), while increasing MAP and CVR compared with placebo. During HUT, in neuropathic POTS, midodrine decreased HR, Q(calf) and C(v), while increasing MAP and CVR. In hyperadrenergic POTS, placebo and midodrine both decreased upright HR and increased supine CVR. Placebo also increased supine C(v), compared with midodrine in hyperadrenergic POTS. Therefore midodrine improved postural tachycardia in neuropathic POTS by increasing CVR and decreasing Q(calf) and C(v), whereas these effects were not seen in hyperadrenergic POTS patients who experienced a placebo effect. This suggests that midodrine is probably an effective treatment for neuropathic POTS, but not for hyperadrenergic POTS.

Caught in the thickness of brain fog: exploring the cognitive symptoms of Chronic Fatigue Syndrome.

Chronic Fatigue Syndrome (CFS) is defined as greater than 6 months of persistent fatigue that is experienced physically and cognitively. The cognitive symptoms are generally thought to be a mild cognitive impairment, but individuals with CFS subjectively describe them as "brain fog." The impairment is not fully understood and often is described as slow thinking, difficulty focusing, confusion, lack of concentration, forgetfulness, or a haziness in thought processes. Causes of "brain fog" and mild cognitive impairment have been investigated. Possible physiological correlates may be due to the effects of chronic orthostatic intolerance (OI) in the form of the Postural Tachycardia Syndrome (POTS) and decreases in cerebral blood flow (CBF). In addition, fMRI studies suggest that individuals with CFS may require increased cortical and subcortical brain activation to complete difficult mental tasks. Furthermore, neurocognitive testing in CFS has demonstrated deficits in speed and efficiency of information processing, attention, concentration, and working memory. The cognitive impairments are then perceived as an exaggerated mental fatigue. As a whole, this is experienced by those with CFS as "brain fog" and may be viewed as the interaction of physiological, cognitive, and perceptual factors. Thus, the cognitive symptoms of CFS may be due to altered CBF activation and regulation that are exacerbated by a stressor, such as orthostasis or a difficult mental task, resulting in the decreased ability to readily process information, which is then perceived as fatiguing and experienced as "brain fog." Future research looks to further explore these interactions, how they produce cognitive impairments, and explain the perception of "brain fog" from a mechanistic standpoint.

A 15-year-old female with amenorrhea, abdominal distention, and elevated human chorionic gonadotropin: pregnancy, right? Not so fast .

Nongestational choriocarcinoma, a rare ovarian tumor, may present in young women with amenorrhea, abdominal distention, and elevated urine human chorionic gonadotropin (hCG), all of which may be mistaken for pregnancy. A 15-year-old Hispanic female, who reported no sexual activity, presented with 6 months of amenorrhea, abdominal pain, and progressive abdominal distension. Initially, suspicion of pregnancy was considered. Physical examination was significant for abdominal distension, but no uterine fundus or fetal anatomy could be palpated, and auscultation did not reveal any fetal heart sounds or bruits. Laboratory values showed elevated urine hCG, cancer antigen 125, and cancer antigen 19.9 levels but normal serum hCG level and was inconsistent with pregnancy. Computed tomographic scans revealed a large abdominal heterogeneous mass and pleural effusions. Salpingo-oophorectomy with total omentectomy and inversion appendectomy removed a 21 × 20.5 × 16.5-cm tumor. Pathological testing determined it to be a nongestational choriocarcinoma. This rare tumor is more common in the pediatric adolescent population than in adults. Surgical resection and chemotherapy often result in a positive prognosis. In female adolescent patients presenting with elevated hCG level, amenorrhea, and abdominal distention, choriocarcinoma should be considered, especially in those with no history of sexual activity or before menarche.

Increasing orthostatic stress impairs neurocognitive functioning in chronic fatigue syndrome with postural tachycardia syndrome.

CFS (chronic fatigue syndrome) is commonly co-morbid with POTS (postural tachycardia syndrome). Individuals with CFS/POTS experience unrelenting fatigue, tachycardia during orthostatic stress and ill-defined neurocognitive impairment, often described as 'mental fog'. We hypothesized that orthostatic stress causes neurocognitive impairment in CFS/POTS related to decreased CBFV (cerebral blood flow velocity). A total of 16 CFS/POTS and 20 control subjects underwent graded tilt table testing (at 0, 15, 30, 45, 60 and 75°) with continuous cardiovascular, cerebrovascular, and respiratory monitoring and neurocognitive testing using an n-back task at each angle. The n-back task tests working memory, concentration, attention and information processing. The n-back task imposes increasing cognitive challenge with escalating (0-, 1-, 2-, 3- and 4-back) difficulty levels. Subject dropout due to orthostatic presyncope at each angle was similar between groups. There were no n-back accuracy or RT (reaction time) differences between groups while supine. CFS/POTS subjects responded less correctly during the n-back task test and had greater nRT (normalized RT) at 45, 60 and 75°. Furthermore, at 75° CFS/POTS subjects responded less correctly and had greater nRT than controls during the 2-, 3- and 4-back tests. Changes in CBFV were not different between the groups and were not associated with n-back task test scores. Thus we conclude that increasing orthostatic stress combined with a cognitive challenge impairs the neurocognitive abilities of working memory, accuracy and information processing in CFS/POTS, but that this is not related to changes in CBFV. Individuals with CFS/POTS should be aware that orthostatic stress may impair their neurocognitive abilities.

Postural neurocognitive and neuronal activated cerebral blood flow deficits in young chronic fatigue syndrome patients with postural tachycardia syndrome.

Neurocognition is impaired in chronic fatigue syndrome (CFS). We propose that the impairment relates to postural cerebral hemodynamics. Twenty-five CFS subjects and twenty control subjects underwent incremental upright tilt at 0, 15, 30, 45, 60, and 75° with continuous measurement of arterial blood pressure and cerebral blood flow velocity (CBFV). We used an n-back task with n ranging from 0 to 4 (increased n = increased task difficulty) to test working memory and information processing. We measured n-back outcomes by the number of correct answers and by reaction time. We measured CBFV, critical closing pressure (CCP), and CBFV altered by neuronal activity (activated CBFV) during each n value and every tilt angle using transcranial Doppler ultrasound. N-back outcome in control subjects decreased with n valve but was independent of tilt angle. N-back outcome in CFS subjects decreased with n value but deteriorated as orthostasis progressed. Absolute mean CBFV was slightly less than in control subjects in CFS subject at each angle. Activated CBFV in control subjects was independent of tilt angle and increased with n value. In contrast, activated CBFV averaged 0 in CFS subjects, decreased with angle, and was less than in control subjects. CCP was increased in CFS subjects, suggesting increased vasomotor tone and decreased metabolic control of CBFV. CCP did not change with orthostasis in CFS subjects but decreased monotonically in control subjects, consistent with vasodilation as compensation for the orthostatic reduction of cerebral perfusion pressure. Increasing orthostatic stress impairs neurocognition in CFS subjects. CBFV activation, normally tightly linked to cognitive neuronal activity, is unrelated to cognitive performance in CFS subjects; the increased CCP and vasomotor tone may indicate an uncoupling of the neurovascular unit during orthostasis.

Cutaneous constitutive nitric oxide synthase activation in postural tachycardia syndrome with splanchnic hyperemia.

Models of microgravity are linked to excessive constitutive nitric oxide (NO) synthase (NOS), splanchnic vasodilation, and orthostatic intolerance. Normal-flow postural tachycardia syndrome (POTS) is a form of chronic orthostatic intolerance associated with splanchnic hyperemia. To test the hypothesis that there is excessive constitutive NOS in POTS, we determined whether cutaneous microvascular neuronal NO and endothelial NO are increased. We performed two sets of experiments in POTS and control subjects aged 21.4 ± 2 yr. We used laser-Doppler flowmetry to measure the cutaneous response to local heating as an indicator of bioavailable neuronal NO. To test for bioavailable endothelial NO, we infused intradermal acetylcholine through intradermal microdialysis catheters and used the selective neuronal NOS inhibitor l-N(ω)-nitroarginine-2,4-L-diamino-butyric amide (N(ω), 10 mM), the selective inducible NOS inhibitor aminoguanidine (10 mM), the nonspecific NOS inhibitor nitro-l-arginine (NLA, 10 mM), or Ringer solution. The acetylcholine dose response and the NO-dependent plateau of the local heating response were increased in POTS compared with those in control subjects. The local heating plateau was significantly higher, 98 ± 1%maximum cutaneous vascular conductance (%CVC(max)) in POTS compared with 88 ± 2%CVC(max) in control subjects but decreased to the same level with N(ω) (46 ± 5%CVC(max) in POTS compared with 49 ± 4%CVC(max) in control) or with NLA (45 ± 3%CVC(max) in POTS compared with 47 ± 4%CVC(max) in control). Only NLA blunted the acetylcholine dose response, indicating that NO produced by endothelial NOS was released by acetylcholine. Aminoguanidine was without effect. This is consistent with increased endothelial and neuronal NOS activity in normal-flow POTS.

Increased pulsatile cerebral blood flow, cerebral vasodilation, and postsyncopal headache in adolescents.

OBJECTIVE: We hypothesize that, after a sudden decrease in cerebral blood flow velocity (CBFV) in adolescents, a faint, rapid hyperemic pulsatile CBFV occurs upon the patient's return to the supine position and is associated with postsyncopal headache. STUDY DESIGN: This case-control study involved 16 adolescent subjects with a history of fainting and headaches. We induced fainting during 70° tilt-table testing and measured mean arterial pressure, heart rate, end-tidal CO(2), and CBFV. Fifteen control subjects were similarly evaluated with a tilt but did not faint, and comparisons with fainters were made at equivalent defined time points. RESULTS: Baseline values were similar between the groups. Upon fainting, mean arterial pressure decreased 49% in the patients who fainted vs 6% in controls (P < .001). The heart rate decreased 15% in fainters and increased 35% in controls (P < .001). In patients who fainted, cerebrovascular critical closing pressure increased markedly, which resulted in reduced diastolic (-66%) and mean CBFV (-46%) at faint; systolic CBFV was similar to controls. Pulsatile CBFV (systolic-diastolic CBFV) increased 38% in fainters, which caused flow-mediated dilatation of cerebral vessels. When the fainters returned to the supine position, CBFV exhibited increased systolic and decreased diastolic flows compared with controls (P < .02). CONCLUSION: Increased pulsatile CBFV during and after faint may cause postsyncopal cerebral vasodilation and headache.

Baroreceptor unloading in postural tachycardia syndrome augments peripheral chemoreceptor sensitivity and decreases central chemoreceptor sensitivity.

While orthostatic tachycardia is the hallmark of postural tachycardia syndrome (POTS), orthostasis also initiates increased minute ventilation (Ve) and decreased end-tidal CO(2) in many patients. We hypothesized that chemoreflex sensitivity would be increased in patients with POTS. We therefore measured chemoreceptor sensitivity in 20 POTS (16 women and 4 men) and 14 healthy controls (10 women and 4 men), 16-35 yr old by exposing them to eucapneic hyperoxia (30% O(2)), eucapneic hypoxia (10% O(2)), and hypercapnic hyperoxia (30% O(2) + 5% CO(2)) while supine and during 70° head-upright tilt. Heart rate, mean arterial pressure, O(2) saturation, end-tidal CO(2), and Ve were measured. Peripheral chemoreflex sensitivity was calculated as the difference in Ve during hypoxia compared with room air divided by the change in O(2) saturation. Central chemoreflex sensitivity was determined by the difference in Ve during hypercapnia divided by the change in CO(2). POTS subjects had an increased peripheral chemoreflex sensitivity (in l·min(-1)·%oxygen(-1)) in response to hypoxia (0.42 ± 0.38 vs. 0.19 ± 0.17) but a decreased central chemoreflex sensitivity (l·min(-1)·Torr(-1)) CO(2) response (0.49 ± 0.38 vs. 1.04 ± 0.18) compared with controls. CO(2) sensitivity was also reduced in POTS subjects when supine. POTS patients are markedly sensitized to hypoxia when upright but desensitized to CO(2) while upright or supine. The interactions between orthostatic baroreflex unloading and altered chemoreflex sensitivities may explain the hyperventilation in POTS patients.

Ascorbate improves circulation in postural tachycardia syndrome.

Low flow postural tachycardia syndrome (LFP) is associated with vasoconstriction, reduced cardiac output, increased plasma angiotensin II, reduced bioavailable nitric oxide (NO), and oxidative stress. We tested whether ascorbate would improve cutaneous NO and reduce vasoconstriction when delivered systemically. We used local cutaneous heating to 42°C and laser Doppler flowmetry to assess NO-dependent conductance (%CVC(max)) to sodium ascorbate and the systemic hemodynamic response to ascorbic acid in 11 LFP patients and in 8 control subjects (aged 23 ± 2 yr). We perfused intradermal microdialysis catheters with sodium ascorbate (10 mM) or Ringer solution. Predrug heat response was reduced in LFP, particularly the NO-dependent plateau phase (56 ± 6 vs. 88 ± 7%CVC(max)). Ascorbate increased baseline skin flow in LFP and control subjects and increased the LFP plateau response (82 ± 6 vs. 92 ± 6 control). Systemic infusion experiments used Finometer and ModelFlow to estimate relative cardiac index (CI) and forearm and calf venous occlusion plethysmography to estimate blood flows, peripheral arterial and venous resistances, and capacitance before and after infusing ascorbic acid. CI increased 40% after ascorbate as did peripheral flows. Peripheral resistances were increased (nearly double control) and decreased by nearly 50% after ascorbate. Calf capacitance and venous resistance were decreased compared with control but normalized with ascorbate. These data provide experimental support for the concept that oxidative stress and reduced NO possibly contribute to vasoconstriction and venoconstriction of LFP.

Reactive oxygen species (ROS) from NADPH and xanthine oxidase modulate the cutaneous local heating response in healthy humans.

Local cutaneous heating produces vasodilation that is largely nitric oxide (NO) dependent. We showed that angiotensin II (ANG II) attenuates this by an ANG II receptor, type 1 (AT1R)-dependent mechanism that is reversible with the antioxidant ascorbate, indicating oxidative stress. Reactive oxygen species (ROS) produced by ANG II employ NADPH and xanthine oxidase pathways. To determine whether these mechanisms pertain to skin, we measured cutaneous local heating with 10 µM ANG II, using apocynin to inhibit NADPH oxidase and allopurinol to inhibit xanthine oxidase. We also inhibited superoxide with tempol, and H(2)O(2) with ebselen. We heated the skin of the calf in 8 healthy volunteers (24.5-29.9 yr old) to 42°C and measured local blood flow to assess the percentage of maximum cutaneous vascular conductance. We remeasured while perfusing allopurinol, apocynin, ebselen, and tempol through individual microdialysis catheters. This was then repeated with ANG II combined with antioxidant drugs. tempol and apocynin alone had no effect on the heat response. Allopurinol enhanced the entire response (125% of heat alone), while ebselen suppressed the heat plateau (76% of heat alone). ANG II alone caused significant attenuation of the entire heat response (52%). When added to ANG II, Allopurinol partially reversed the ANG II attenuation. Heat with ebselen and ANG II were similar to heat and ANG II; ebselen only partially reversed the ANG II attenuation. Apocynin and tempol each partially reversed the attenuation caused by ANG II. This suggests that ROS, produced by ANG II via NADPH and xanthine oxidase pathways, modulates the response of skin to the application of heat, and thus contributes to the control of local cutaneous blood flow.