Cadmium body burden and increased blood pressure in middle-aged American Indians: the Strong Heart Study.

Cadmium (Cd) is an environmental pollutant that has been associated with cardiovascular disease in populations, but the relationship of Cd with hypertension has been inconsistent. We studied the association between urinary Cd concentrations, a measure of total body burden, and blood pressure in American Indians, a US population with above national average Cd burden. Urinary Cd was measured using inductively coupled plasma mass spectrometry, and adjusted for urinary creatinine concentration. Among 3714 middle-aged American Indian participants of the Strong Heart Study (mean age 56 years, 41% male, 67% ever-smokers, 23% taking antihypertensive medications), urinary Cd ranged from 0.01 to 78.48 µg g-1 creatinine (geometric mean=0.94 µg g-1) and it was correlated with smoking pack-year among ever-smokers (r2=0.16, P<0.0001). Participants who were smokers were on average light-smokers (mean 10.8 pack-years), and urinary Cd was similarly elevated in light- and never-smokers (geometric means of 0.88 µg g-1 creatinine for both categories). Log-transformed urinary Cd was significantly associated with higher systolic blood pressure in models adjusted for age, sex, geographic area, body mass index, smoking (ever vs never, and cumulative pack-years) and kidney function (mean blood pressure difference by lnCd concentration (ß)=1.64, P=0.002). These associations were present among light- and never-smokers (ß=2.03, P=0.002, n=2627), although not significant among never-smokers (ß=1.22, P=0.18, n=1260). Cd was also associated with diastolic blood pressure among light- and never-smokers (ß=0.94, P=0.004). These findings suggest that there is a relationship between Cd body burden and increased blood pressure in American Indians, a population with increased cardiovascular disease risk.

Sex differences in obesity prevalence and cardiometabolic factors among Western Alaska Native people.

BACKGROUND AND AIMS: Obesity is associated with increased risks of cardiovascular disease, type 2 diabetes, and other chronic diseases. Prevalence estimates for metabolic disorders are well documented in many populations, but Alaska Native groups are understudied. The Western Alaska Tribal Collaborative for Health Study combines data from three Alaska Native study cohorts to assess differences in obesity prevalence and associations with cardiometabolic risk factors by sex. METHODS AND RESULTS: Analyses were based upon a sample of 3985 adult Yup'ik and Inupiat participants with a mean age of 40 years. Prevalence of obesity and metabolic risk factors was assessed according to nationally recognized guidelines. Regression analysis was used to evaluate the association between obesity and cardiometabolic risk factors, including lipids, blood pressure and glucose. The prevalence of obesity (BMI ≥ 30) was significantly higher in women (40%) than men (20%). Only 18.6% of men had a waist circumference (WC) > 102 cm, while 58% of women had a WC > 88 cm (p < 0.001). Women had higher mean HDL-C and triglyceride levels compared to men, while systolic and diastolic blood pressure, LDL-C, and glucose means were higher in men than in women. In multivariate analyses, BMI and WC were significantly associated with all of the cardiometabolic risk factors, although these associations were more pronounced in men than women. CONCLUSION: The high prevalence of obesity and central adiposity among AN women is an important public health concern. Differences in associations between obesity and cardiometabolic risk factors by sex warrants further investigation to develop effective intervention programs.

Serum uric acid does not predict incident metabolic syndrome in a population with high prevalence of obesity.

AIM: To evaluate whether uric acid (UA) predicts 4-yr incidence of metabolic syndrome (MetS) in non-diabetic participants of the Strong Heart Study (SHS) cohort. METHODS AND RESULTS: In this population-based prospective study we analyzed 1499 American Indians (890 women), without diabetes or MetS, controlled during the 4th SHS exam and re-examined 4 years later during the 5th SHS exam. Participants were divided into sex-specific tertiles of UA and the first two tertiles (group N) were compared with the third tertile (group H). Body mass index (BMI = 28.3 ± 7 vs. 31.1 ± 7 kg/m(2)), fat-free mass (FFM = 52.0 ± 14 vs. 54.9 ± 11 kg), waist-to-hip ratio, HOMA-IR (3.66 vs. 4.26), BP and indices of inflammation were significantly higher in group H than in group N (all p < 0.001). Incident MetS at the time of the 5th exam was more frequent in group H than group N (35 vs. 28%, OR 1.44 (95% CI = 1.10-1.91; p < 0.01). This association was still significant (OR = 1.13, p = 0.04) independently of family relatedness, sex, history of hypertension, HOMA-IR, central adiposity and renal function, but disappeared when fat-free mass was included in the model. CONCLUSIONS: In the SHS, UA levels are associated to parameters of insulin resistance and to indices of inflammation. UA levels, however, do not predict incident MetS independently of the initial obesity-related increased FFM.

A Semi-Mechanistic Metabolism Model of CYP3A Substrates in Pregnancy: Predicting Changes in Midazolam and Nifedipine Pharmacokinetics.

Physiological changes in pregnancy, including changes in body composition and metabolic enzyme activity, can alter drug pharmacokinetics. A semi-mechanistic metabolism model was developed to describe the pharmacokinetics of two cytochrome P450 3A (CYP3A) substrates, midazolam and nifedipine, in obstetrics patients. The model parameters were optimized to fit the data of oral midazolam pharmacokinetics in pregnant women, by increasing CYP3A-induced hepatic metabolism 1.6-fold in the model with no change in gut wall metabolism. Fetal metabolism had a negligible effect on maternal plasma drug concentrations. Validation of the model was performed by applying changes in volume of distribution and metabolism, consistent with those observed for midazolam, to the pharmacokinetics parameters of immediate-release nifedipine in healthy volunteers. The predicted steady-state areas under the concentration-time curve (AUCs) for nifedipine were within 15% of the data observed in pregnant women undergoing treatment for preterm labor. This model predicts the pharmacokinetics of two CYP3A substrates in pregnancy, and may be applicable to other CYP3A substrates as well.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e2; doi:10.1038/psp.2012.5; advance online publication 26 September 2012.

Pharmacokinetic studies in hemodialysis patients.

Intermittent hemodialysis is the primary supportive therapy for patients with end-stage renal disease, who commonly receive several drugs to treat both their underlying disease and the conditions that arise during long-term hemodialysis therapy. Many of these drugs are dialyzable, and their hemodialytic removal may compromise therapeutic efficacy if appropriate supplementary doses are not given. Emergency hemodialysis may also be life-saving for patients who have received drug overdoses or have ingested toxic substances. Optimal therapy in both these clinical settings is critically dependent on the availability of reliable information from well-designed pharmacokinetic studies.

Are we optimizing gestational diabetes treatment with glyburide? The pharmacologic basis for better clinical practice.

Glyburide's pharmacokinetics (PK) and pharmacodynamics have not been studied in women with gestational diabetes mellitus (GDM). The objective of this study was to assess steady-state PK of glyburide, as well as insulin sensitivity, beta-cell responsivity, and overall disposition indices after a mixed-meal tolerance test (MMTT) in women with GDM (n = 40), nonpregnant women with type 2 diabetes mellitus (T2DM) (n = 26), and healthy pregnant women (n = 40, MMTT only). At equivalent doses, glyburide plasma concentrations were approximately 50% lower in pregnant women than in nonpregnant subjects. The average umbilical cord/maternal plasma glyburide concentration ratio at the time of delivery was 0.7 +/- 0.4. Insulin sensitivity was approximately fivefold lower in women with GDM as compared with healthy pregnant women. Despite comparable beta-cell responsivity indices, the average beta-cell function corrected for insulin resistance was more than 3.5-fold lower in women with glyburide-treated GDM than in healthy pregnant women. Women with GDM in whom glyburide treatment has failed may benefit from alternative medication or dosage escalation; however, fetal safety should be kept in mind.

Assessing the impact of different imputation methods on serial measures of renal function: the Strong Heart Study.

Missing data are a common problem in epidemiologic studies. This study had two aims: (a) to determine which method for imputing missing renal function data provides estimates closest to those made with complete data and (b) to determine which measure of renal function better estimates cardiovascular disease (CVD) risk. For these analyses, a subset of Strong Heart Study participants with complete data for renal function was identified. Data were randomly dropped from this complete set at three rates: 30, 45, and 60%. Five common techniques for handling missing data were compared: imputation using the mean, adjacent value (AV), single imputation, multiple imputation, and listwise deletion. Differences between the imputed sets and the complete set were determined for each method. Imputation methods were used to fill in missing values for serum creatinine (Scr) in one model and estimated glomerular filtration rate (eGFR) in another. For both Scr and eGFR, the AV method provided the most favorable results in predicting CVD risk, regardless of the rate of missing data.

Antihypertensive therapy in pregnancy.

Human pregnancy, normally characterized by systemic vasodilation and modest hypotension, can be complicated by underlying maternal hypertension and several unique hypertensive disorders, including pre-eclampsia. Although well-designed and adequately powered clinical trials are critically needed, there have been several recent meta-analyses of this large literature, along with consensus statements and treatment guidelines from three distinct multidisciplinary groups of clinicians and investigators. In this paper we review recent analyses and guidelines, advising on our current approach to antihypertensive therapy in pregnant women.

Nitric oxide dependent and independent effects of in vitro incubation or endotoxin on vascular reactivity in rat aorta.

We sought to delineate contributions of nitric oxide (NO) and other mechanisms to impairment of contraction and endothelium-dependent relaxation following prolonged in vitro incubation, endotoxin and interleukin-1 exposure in isolated rat aorta. Responses from freshly-dissected (control) rings +/-endothelium were compared with those from rings incubated in sterile, antibiotic containing medium +/- E. Coli endotoxin (LPS, 100 microg/ml) +/- interleukin-1 (IL-1, 40 ng/ml) at 37 degrees C for 20-24 h. In some experiments, medium included dexamethasone (DEX, 1 microg/ml), cycloheximide (10 microg/ml), or N(G)-nitro-L-arginine (NNLA, 10(-4)M). After incubation, medium nitrite was measured. Incubation alone, without addition of inflammatory mediators, impaired contraction in an agonist-specific manner, by both NO-dependent and NO-independent mechanisms. Either LPS or IL-1 diminished contraction further, in a similarly heterogeneous manner. For example, contractions were changed in LPS-incubated endothelium-intact rings (vs. fresh controls) by -85%, +115%, -15%, -96%, and -37% for phenylephrine (PE), serotonin, prostaglandin F2alpha, angiotensin II, and U46619, respectively. NO synthase inhibition with NNLA either following, or during LPS incubation only partially normalized subsequent PE contractions, an effect which was smaller than that of DEX. Nitrite accumulation was inversely proportional to PE response, even though NO was not the sole mediator of LPS-impaired contraction. LPS and IL-1 nearly abolished ACh-induced relaxation, which was only mildly impaired by incubation alone. We conclude that prolonged incubation impaired vasoconstriction via both NO synthase induction and NO-independent mechanisms. LPS or IL-1 incubation impaired vasoconstriction further, primarily by NO-independent mechanisms. Moreover, vasoconstrictor responses following LPS varied with the agonist's ability to modulate endothelial NO release. These results are in accord with the failure of NO synthase inhibition to fully restore systemic vascular resistance indices in experimental endotoxemia or in hyperdynamic septic patients.

Connexin expression is not altered in omental resistance vessels from women with preeclampsia.

OBJECTIVE: To compare connexin expression in omental resistance arteries from preeclamptic women and normal gravidas. METHODS: Small arteries (approximately 200-400 microm i.d.) were dissected from omental fat biopsies, taken at cesarean delivery from normotensive and preeclamptic women. Vessels were frozen and homogenized, then connexin-43 protein was detected by Western blot and quantitated by comparison with alpha-actin. RESULTS: Connexin-43 was detected in all specimens, primarily in its phosphorylated form. Abundance did not differ between vessels from preeclamptic and normotensive gravidas. CONCLUSIONS: Phasic activity in omental resistance vessels from preeclamptic women likely depends on abnormal genesis of an oscillatory signal rather than on more extensive gap junctional communication between vascular cells.

Possible role of P-450-derived metabolites in endothelium-dependent relaxation of rat small mesenteric arteries.

We reported previously that acetylcholine (ACh)-induced endothelium-dependent relaxation of rat mesenteric microvessels depended both on nitric oxide (NO) and on a charybdotoxin (CTX)-sensitive endothelium-derived hyperpolarizing vasodilator. Cytochrome P450 (CYP)-dependent arachidonic acid metabolites act in some systems as hyperpolarizing vasodilators. We sought to quantitate contributions of such metabolites to the CTX-sensitive component of ACh-induced vasodilation in isolated rat mesenteric resistance arteries. ACh relaxed these vessels nearly completely (93.3+/-1.2%, n = 71); cyclooxygenase inhibition with indomethacin did not diminish this response (94.3+/-11.4%, n = 9). NO synthase inhibition with Nitro-L-arginine (NNLA) reduced relaxation by 30% (n = 54, p<0.05). Pretreatment of vessels with CYP inhibitors, either clotrimazole (CTM) or 17-octadecynoic acid (17-ODYA), or with selective K+ channel inhibitors, either tetraethyammonium acetate (TEA) or CTX, each led to similar small reductions in maximal relaxation (17%, 22%, 16%, and 9% respectively, n = 3-6). Combined pretreatment with NNLA + either (CTM or 17-ODYA) or (TEA or CTX) each led to similar maximal relaxations (52.2+/-4.8%, 50.6+/-9.2, 37.6+/-8.6%, and 44.1+/-11.5%, respectively, n = 6-35; p<0.05 for NNLA+[CTM or TEA or CTX] vs NNLA alone). Combined pretreatment with NNLA+CTM+(CTX or TEA) led to similar maximal relaxations (43.0+/-7.3%, 43.7+/-15%, n = 6-11) that did not differ from values in vessels pretreated with either NNLA+CTM or NNLA+(CTX or TEA). We conclude that the ACh-induced vasodilation was insensitive to cyclooxygenase inhibition, partially sensitive to NO synthase inhibition, and that the K+ channel blockers TEA and CTX identified the same minor component of ACh relaxation as did the CYP inhibitor CTM.

Safety of losartan in hypertensive patients with thiazide-induced hyperuricemia.

BACKGROUND: Losartan, an angiotensin II receptor antagonist, has been shown to decrease serum uric acid and to increase urinary excretion of uric acid. METHODS: To determine if this effect can increase the risk of acute urate nephropathy, 63 hypertensive patients with thiazide-induced asymptomatic hyperuricemia (serum uric acid 7.0 to 12.0 mg/dl) were randomized double-blind to losartan 50 mg every day (q.d.), losartan 50 mg plus hydrochlorothiazide (HCTZ) 50 mg q.d., HCTZ 50 mg q.d., or placebo for three weeks. To potentiate the risk of crystal formation, patients received a 2 g/kg protein diet one day prior to each clinic visit on days 0 (baseline), 1, 7, and 21. RESULTS: Adverse events typically associated with acute urate nephropathy, for example, flank pain, hematuria, or increased blood urea nitrogen/creatinine, were not reported. Uric acid excretion and urine pH increased four and six hours after losartan on day 1 compared with day 0. Dihydrogen urate, the primary risk factor for crystal formation, decreased at four and six hours on day 1 compared with day 0 associated with the concurrent rise in urine pH. Day 7 and 21 changes, compared with day 0, in uric acid excretion rate, urine pH, and dihydrogen urate with losartan were comparable to day 1 results but were not statistically significant. Serum uric acid was significantly reduced after 21 days of therapy with losartan. CONCLUSION: Losartan decreased serum uric acid and increased uric acid excretion without increasing urinary dihydrogen urate, the primary risk factor for acute urate nephropathy, during 21 days of dosing in hypertensive patients with thiazide-induced hyperuricemia.

Attention and mental processing speed in hemodialysis patients.

It has remained unclear whether well-dialyzed patients with end-stage renal disease (ESRD) show persisting neurocognitive deficits, especially in tasks that depend on sustained attention or psychomotor speed. We administered a battery of six attentional measures to 10 stable hemodialysis (HD) patients (age, 61+/-16 years; education, 12.4+/-3.8 years; Kt/V, 1.35+/-0.07) and 10 matched controls with normal renal function (age, 62+/-10 years; education, 11.6+/-1.0 years; estimated creatinine clearance, 92+/-25 mL/min). Results of the Trailmaking Test, Paced Auditory Serial Addition Test, Stroop Test, Digit Span, Continuous Performance Test (CPT), and Gordon Diagnostic System did not differ between groups. We conclude it is unlikely that well-dialyzed patients with ESRD manifest significant uremic neurocognitive deficits in the functional spheres related to sustained attention or mental processing speed.

Selectivity of endotoxin-induced defect in endothelial calcium mobilization.

BACKGROUND: We hypothesized that endotoxin (LPS) would impair bradykinin (BK)-induced calcium (Ca2+) mobilization in aortic endothelial cells, perhaps due to cytotoxicity or via stimulation of nitric oxide (NO) synthesis. As well, we sought to define contributions of LPS-stimulated Ca2+ mobilization to these effects. METHODS: LPS- or BK-induced increments of intracellular Ca2+ were assessed by microspectrofluorimetry with fura-2 in passaged bovine aortic endothelial cells. Time- and dose-dependent effects of LPS exposure (+/- inhibitors of NO or prostaglandin synthesis) on subsequent BK-induced Ca2+ mobilization and on attached cell counts were determined. RESULTS: LPS (0.1 to 1.0 mg/ml) led to rapid increments of Ca2+, while Ca2+ responses were delayed following LPS (1 to 10 microg/ml) and lower doses were without effect. By contrast, LPS more potently (1.0 pg to 1.0 microg/ml) led to dose- and time-dependent impairment of subsequent BK-induced Ca2+ mobilization, with peak effect at four to six hours, persisting for at least 18 hours. This delayed effect on BK-response was unaltered by inhibition of either NO synthase or cyclooxygenase. The effect of LPS on BK-responsivity depended importantly on cell confluence, as it was not observed in subconfluent cells. By contrast, LPS-induced cell detachment, which was observed only at doses > or = 1.0 microg/ml, did not depend on confluence. CONCLUSIONS: Different mechanisms lead to endothelial cytotoxicity and to impaired BK-response following LPS. Only the former effect, occurring at higher doses, might depend on initial LPS-induced Ca2+ mobilization.

Eosinophils, major basic protein, and polycationic peptides augment bovine airway myocyte Ca2+ mobilization.

Previous studies in vivo or in isolated airway preparations have suggested that eosinophil-derived polycationic proteins enhance airway smooth muscle tone in an epithelium-dependent manner. We assessed the direct effects of activated human eosinophil supernatant, major basic protein (MBP), and polycationic polypeptides on basal and agonist-stimulated intracellular Ca2+ concentrations ([Ca2+]i) in cultured bovine tracheal smooth muscle (TSM) cells. A 1-h incubation of myocytes with activated eosinophil buffer resulted in a doubling of basal [Ca2+]i and increased responsivity to histamine compared with myocytes that were exposed to sham-activated eosinophil buffer. In addition, concentration-dependent acute transient increases and subsequent 1-h sustained elevations of basal [Ca2+]i were observed immediately after addition of MBP and model polycationic proteins. Finally, both peak and plateau [Ca2+]i responses to bradykinin addition were augmented significantly in cultured myocytes that had been exposed to low concentrations of MBP or model polycationic proteins but were inhibited at greater concentrations. This elevated [Ca2+]i to polycationic proteins was manifest in epithelium-denuded bovine TSM strips as concentration-dependent increased basal tone. We conclude that activated eosinophil supernatant, MBP, and other polycationic proteins have a direct effect on both basal and subsequent agonist-elicited Ca2+ mobilization in cultured TSM cells; TSM strips in vitro demonstrated, respectively, augmented and diminished responses to the contractile agonist acetylcholine. It is possible that alteration in myocyte Ca2+ mobilization induced by these substances may influence clinical states of altered airway tone, such as asthma.

Endotoxin impairs agonist-induced calcium mobilization in bovine aortic myocytes by a nitric oxide-independent mechanism.

We hypothesized that endotoxin (LPS) would impair vasoconstrictor-agonist-induced calcium (Ca2+) mobilization by a nitric oxide (NO)-dependent mechanism. We incubated bovine aortic myocytes (passages 16 to 23) for 22 to 24 hours with 0 to 1.0 mg/ml Escherichia coli lipopolysaccharide (LPS). Medium (Dulbecco's modified Eagle's medium (DMEM) + 10% fetal bovine serum (FBS)) was assayed for nitrite (chemiluminescence), and myocytes were loaded with fura-2 acetoxymethyl ester (fura-2AM), after which we assessed basal and thrombin (10 U/ml)-induced peak Ca2+ mobilization by microspectrofluorimetry. LPS (0.01 to 1.0 mg/ml) led to dose-dependent nitrite accumulation, which was blocked by coincubation with N(omega)-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L). LPS also impaired Ca2+ responses in a dose-dependent manner (from -13% at 0.1 mg/ml to -47% at 1.0 mg/ml, n = 8 to 43/dose). However, coincubation with L-NAME did not ameliorate the Ca2+ mobilization defect (peak Ca2+ increments: control = 419 +/-30 nmol/L, vs LPS (1 mg/ml) = 206+/-18 nmol/L (mean+/-SE), n = 15; p < 0.001; control/L-NAME: 417+/-31 nmol/L vs LPS/L-NAME: 212+/-19 nmol/L; n = 17 p < 0.001), despite inhibition of associated nitrite accumulation in the medium (control vs LPS: p < 0.001; control/L-NAME vs LPS/L-NAME: p > 0.05; LPS vs LPS/L-NAME: p < 0.001). Supplemental L-arginine augmented LPS-induced nitrite generation without affecting Ca2+ mobilization. Indomethacin failed to prevent the LPS-induced decrement in thrombin response, but did inhibit LPS-induced myocyte nitrite production, suggesting "crosstalk" between the NO-synthase and cyclo-oxygenase (COX) systems. These experiments suggest that LPS-induced vascular contractile impairment is at least partly mediated by an NO-independent impairment of agonist-induced myocyte Ca2+ mobilization. This further suggests that any important contribution of NO synthesis to LPS-induced contractile dysfunction must depend on impairment of the Ca2+ sensitivity of the contractile apparatus (i.e., pharmacomechanical coupling).

Preeclampsia selectively impairs endothelium-dependent relaxation and leads to oscillatory activity in small omental arteries.

The vascular pathophysiology of preeclampsia, a hypertensive disorder unique to human pregnancy, has been postulated to be due to endothelial dysfunction, primarily manifest as deficient nitric oxide (NO) synthesis. We evaluated contraction (KCl and arginine vasopressin [AVP]) and dilation (acetylcholine and bradykinin) in small resistance-size omental arteries obtained during surgery from women with preeclampsia, postulating that these vessels would exhibit augmented contraction and diminished endothelium-dependent relaxation, most likely due to decreased NO synthesis. For comparison, vessels were also obtained from normotensive gravidas, pregnant women with chronic hypertension, or with chronic hypertension and superimposed preeclampsia, as well as from premenopausal nonpregnant controls. Vessels of approximately 200 micron in internal diameter were studied in vitro using a Mulvany-Halpern myograph. Maximal contraction due to either KCl or AVP was significantly augmented in vessels from women with preeclampsia; these vessels all exhibited endothelium- and cyclooxygenase-dependent phasic oscillations while vessels from all other groups exhibited only tonic contractions. Acetylcholine and bradykinin both led to dose- and endothelium-dependent relaxation which was unaffected by inhibitors of NO synthesis. Responses to bradykinin were similar in vessels from normal pregnant and preeclamptic women while those to acetylcholine were absent in vessels from women with preeclampsia. These data suggest specific defects in resistance-artery endothelium from women with preeclampsia.

Endotoxin impairs agonist-induced calcium mobilization in rat mesangial cells.

We hypothesized that endotoxin would impair agonist-induced calcium (Ca2+) mobilization in rat mesangial cells, owing to the induction of nitric oxide synthase (NOS) and augmented nitric oxide (NO) synthesis. We measured basal and bradykinin-induced peak free cytosolic Ca2+ concentrations through microspectrofluorimetry with fura-2 in confluent mesangial cells, and assayed conditioned medium for nitrite accumulation. Prior to measurement, cells were incubated overnight in serum-supplemented medium, with or without endotoxin, 1-arginine, indomethacin, meclofenamate, or N omega-nitro-L-arginine methyl ester (L-NAME). Endotoxin (1 mg/ml) decreased bradykinin-induced peak Ca2+ responses by 35 to 60% (p < 0.0001) and increased nitrite accumulation > 6-fold (p < 0.01). Arginine supplementation further (> 9-fold, p < 0.0001) increased nitrite accumulation without changing the effect on Ca2+. Inhibition of NOS abolished increments in nitrite concentration but had no effect on impaired Ca2+ responses. Cyclooxygenase (COX) inhibitors, present during incubation with endotoxin, but not afterward, normalized bradykinin-stimulated calcium responses. Thrombin-stimulated Ca2+ responses were similarly affected. We conclude that neither NO nor prostaglandins act directly to impair agonist-induced Ca2+ mobilization following endotoxin exposure; however, this effect may be an indirect effect of COX products, including reactive oxygen intermediates.