TRPA1 Polymorphisms Modify the Hypotensive Responses to Propofol with No Change in Nitrite or Nitrate Levels

Anesthesia with propofol is frequently associated with hypotension. The TRPA1 gene contributes to the vasodilator effect of propofol. Hypotension is crucial for anesthesiologists because it is deleterious in the perioperative period. We tested whether the TRPA1 gene polymorphisms or haplotypes interfere with the hypotensive responses to propofol. PCR-determined genotypes and haplotype frequencies were estimated. Nitrite, nitrates, and NOx levels were measured. Propofol induced a more expressive lowering of the blood pressure (BP) without changing nitrite or nitrate levels in patients carrying CG+GG genotypes for the rs16937976 TRPA1 polymorphism and AG+AA genotypes for the rs13218757 TRPA1 polymorphism. The CGA haplotype presented the most remarkable drop in BP. Heart rate values were not impacted. The present exploratory analysis suggests that TRPA1 genotypes and haplotypes influence the hypotensive responses to propofol. The mechanisms involved are probably other than those related to NO bioavailability. With better genetic knowledge, planning anesthesia with fewer side effects may be possible.

Gene-gene interactions in the protein kinase C/endothelial nitric oxide synthase axis impact the hypotensive effects of propofol

Anaesthesia with propofol is frequently associated with hypotension, which is at least partially attributable to increased nitric oxide (NO) formation derived from the activation of protein kinase C (PKC)/endothelial NO synthase (NOS3) axis. In this cross-sectional study, we tested whether PRKCA (which encodes PKCα) polymorphisms, or haplotypes, and interactions among PRKCA and NOS3 polymorphisms affect the hypotensive responses to propofol. We collected venous blood samples from 164 patients before and 10 min after propofol administration. Genotypes were determined by PCR and haplotype frequencies were estimated. Nitrite and NO_x (nitrites+nitrates) levels were measured by using an ozone-based chemiluminescence assay and the Griess reaction, respectively. We used multifactor dimensionality reduction to test interactions among PRKCA and NOS3 polymorphisms. Propofol promoted enhanced blood pressure-lowering effects and increased nitrite levels in subjects carrying GA + AA genotypes for the rs16960228 and TC + CC genotypes for the rs1010544 PRKCA polymorphisms, and the CCG haplotype. Moreover, genotypes for the rs1010544 PRKCA polymorphism were associated with higher or lower blood pressure decreases in response to propofol depending on the genotypes for the rs2070744 NOS3 polymorphism. Our findings suggest that PRKCA genotypes and haplotypes impact the hypotensive responses to propofol, possibly by modifying NO bioavailability, and that PRKCA-NOS3 interactions modify the blood pressure-lowering effects of propofol.

Increased O-GlcNAcylation of Endothelial Nitric Oxide Synthase Compromises the Anti-contractile Properties of Perivascular Adipose Tissue in Metabolic Syndrome

Under physiological conditions, the perivascular adipose tissue (PVAT) negatively modulates vascular contractility. This property is lost in experimental and human obesity and in the metabolic syndrome, indicating that changes in PVAT function may contribute to vascular dysfunction associated with increased body weight and hyperglycemia. The O-linked β-N-acetylglucosamine (O-GlcNAc) modification of proteins (O-GlcNAcylation) is a unique posttranslational process that integrates glucose metabolism with intracellular protein activity. Increased flux of glucose through the hexosamine biosynthetic pathway and the consequent increase in tissue-specific O-GlcNAc modification of proteins have been linked to multiple facets of vascular dysfunction in diabetes and other pathological conditions. We hypothesized that chronic consumption of glucose, a condition that progresses to metabolic syndrome, leads to increased O-GlcNAc modification of proteins in the PVAT, decreasing its anti-contractile effects. Therefore, the current study was devised to determine whether a high-sugar diet increases O-GlcNAcylation in the PVAT and how increased O-GlcNAc interferes with PVAT vasorelaxant function. To assess molecular mechanisms by which O-GlcNAc contributes to PVAT dysfunction, thoracic aortas surrounded by PVAT were isolated from Wistar rats fed either a control or high sugar diet, for 10 and 12 weeks. Rats chronically fed a high sugar diet exhibited metabolic syndrome features, increased O-GlcNAcylated-proteins in the PVAT and loss of PVAT anti-contractile effect. PVAT from high sugar diet-fed rats for 12 weeks exhibited decreased NO formation, reduced expression of endothelial nitric oxide synthase (eNOS) and increased O-GlcNAcylation of eNOS. High sugar diet also decreased OGA activity and increased superoxide anion generation in the PVAT. Visceral adipose tissue samples from hyperglycemic patients showed increased levels of O-GlcNAc-modified proteins, increased ROS generation and decreased OGA activity. These data indicate that O-GlcNAcylation contributes to metabolic syndrome-induced PVAT dysfunction and that O-GlcNAcylation of eNOS may be targeted in the development of novel therapies for vascular dysfunction in conditions associated with hyperglycemia.

Endothelial nitric oxide synthase polymorphisms affect the changes in blood pressure and nitric oxide bioavailability induced by propofol

Propofol anesthesia is usually accompanied by hypotension, which is at least in part related to enhanced endothelial nitric oxide synthase (NOS3)-derived NO bioavailability. We examined here whether NOS3 polymorphisms (rs2070744, 4b/4a VNTR, rs3918226 and rs1799983) and haplotypes affect the changes in blood pressure and NO bioavailability induced by propofol. Venous blood samples were collected from 168 patients at baseline and after 10 min of anesthesia with propofol 2 mg/kg administered intravenously by bolus injection. Genotypes were determined by polymerase chain reaction and haplotype frequencies were estimated. Nitrite concentrations were measured by using an ozone-based chemiluminescence assay, while NOx (nitrites + nitrates) levels were determined by using the Griess reaction. We found that CT + TT genotypes for the rs3918226 polymorphism, the ba + aa genotypes for the 4b/4a VNTR and the CTbT haplotype were associated with lower decreases in blood pressure and lower increases in nitrite levels after propofol anesthesia. On the other hand, the TCbT and CCbT haplotypes were associated with more intense decreases in blood pressure and higher increases in nitrite levels in response to propofol. Our results suggest that NOS3 polymorphisms and haplotypes influence the hypotensive responses to propofol, possibly by affecting NO bioavailability.

Angiotensin converting enzyme inhibitors enhance the hypotensive effects of propofol by increasing nitric oxide production

Propofol anesthesia is usually accompanied by hypotension. Studies have shown that the hypotensive effects of propofol increase in patients treated with angiotensin-converting enzyme inhibitors (ACEi). Given that both propofol and ACEi affect nitric oxide (NO) signaling, the present study tested the hypothesis that ACEi treatment induces pronounced hypotensive responses to propofol by increasing NO bioavailability. In this study we evaluated 65 patients, divided into three groups: hypertensive patients chronically treated with ACEi (HT-ACEi; n = 21), hypertensive patients treated with other antihypertensive drugs instead of ACEi, such as angiotensin II receptor blockers, β-blockers or diuretics (HT; n = 21) and healthy normotensive subjects (NT; n = 23). Venous blood samples were collected at baseline and after 10min of anesthesia with propofol 2mg/kg administrated intravenously by bolus injection. Hemodynamic parameters were recorded at each blood sample collection. Nitrite levels were determined by using an ozone-based chemiluminescence assay, while NOx (nitrites+nitrates) levels were measured by using the Griess reaction. Additionally, experimental approaches were used to validate our clinical findings. Higher decreases in blood pressure after propofol anesthesia were observed in HT-ACEi group as compared with those found in NT and HT groups. Consistently, rats treated with the ACEi enalapril showed more intense hypotensive responses to propofol. The hypotensive effects of propofol were associated with increased NO production in both clinical and experimental approaches. Enhanced increases in nitrite levels after propofol anesthesia were observed in HT-ACEi patients compared with NT and HT groups. Accordingly, rats treated with enalapril showed increased vascular NO formation after propofol anesthesia compared with rats receiving vehicle. Our data show that ACEi enhance the hypotensive responses to propofol anesthesia and increase nitrite concentrations. These findings suggest that increased NO bioavailability may account for the enhanced hypotensive effects of propofol in ACEi-treated patients.

Use of neuron-specific enolase for assessing the severity and outcome of neurological disorders in patients

Neuron-specific enolase (NSE) is a glycolytic enzyme present almost exclusively in neurons and neuroendocrine cells. NSE levels in cerebrospinal fluid (CSF) are assumed to be useful to estimate neuronal injury and clinical outcome of patients with serious clinical manifestations such as those observed in stroke, head injury, anoxic encephalopathy, encephalitis, brain metastasis, and status epilepticus. We compared levels of NSE in serum (sNSE) and in CSF (cNSE) among four groups: patients with meningitis (N=11), patients with encephalic injuries associated with impairment of consciousness (ENC, N=7), patients with neurocysticercosis (N=25), and normal subjects (N=8). Albumin was determined in serum and CSF samples, and the albumin quotient was used to estimate blood-brain barrier permeability. The Glasgow Coma Scale score was calculated at the time of lumbar puncture and the Glasgow Outcome Scale (GOS) score was calculated at the time of patient discharge or death. The ENC group had significantly higher cNSE (P=0.01) and albumin quotient (P=0.005), but not sNSE (P=0.14), levels than the other groups (Kruskal-Wallis test). Patients with lower GOS scores had higher cNSE levels (P=0.035) than patients with favorable outcomes. Our findings indicate that sNSE is not sensitive enough to detect neuronal damage, but cNSE seems to be reliable for assessing patients with considerable neurological insult and cases with adverse outcome. However, one should be cautious about estimating the severity of neurological status as well as outcome based exclusively on cNSE in a single patient.

Effects of intrathecal sufentanil on plasma oxytocin and cortisol concentrations in women during the first stage of labor

BACKGROUND AND OBJECTIVES

Intrathecal sufentanil provides analgesia comparable to epidural bupivacaine for the first stage of labor. Both epidural local anesthetics and intrathecal opioid reduce some parameters of the neuroendocrine response to labor pain and the reflex release of oxytocin in animals. In humans, epidural local anesthetics only reduce the spurt release of oxytocin. This study compared the effect of intrathecal sufentanil and epidural bupivacaine administration on the plasma concentration of oxytocin and cortisol in women with labor pain during the first stage of labor.

METHODS

Thirty healthy parturients requesting analgesia were enrolled in this randomized and open-label study. Each patient was in spontaneous labor at greater than 5 cm cervical dilatation. Using a combined spinal and epidural technique, patients received either intrathecal sufentanil 10 microg (SUF = intrathecal sufentanil group) or epidural plain bupivacaine 0.25%, 12 mL (BUPIV = epidural bupivacaine group). Analgesia was assessed using a visual analog scale, and blood samples for oxytocin and cortisol plasma concentration measurements were collected immediately before analgesia and 15, 30, 60, and 90 minutes after induction of the analgesia. Plasma cortisol and oxytocin concentrations were determined by specific radioimmunoassay. The values were expressed as mean +/- SEM.

RESULTS

Intrathecal sufentanil provided faster and more complete analgesia within 15 and 30 minutes of its administration, compared with epidural bupivacaine. Plasma oxytocin concentrations were similar in the 2 groups before analgesia (7.24 +/- 2.1 and 6.6 +/- 3.1 pg/mL SUF and BUPIV, respectively). It decreased significantly in the SUF and increased in the BUPIV after analgesic administration. Cortisol concentrations were elevated in both groups before analgesia (51.6 +/- 5.3 and 54.2 +/- 4.8 microg/dL SUF and BUPIV, respectively). Both analgesic treatments significantly decreased the plasma cortisol levels.

CONCLUSIONS

Intrathecal sufentanil analgesia decreases plasma concentrations of oxytocin and cortisol in women with labor pain during the first stage of labor, but epidural bupivacaine only reduced the cortisol concentration.

Labor analgesia in a patient with paroxysmal nocturnal hemoglobinuria with thrombocytopenia

BACKGROUND AND OBJECTIVES

Paroxysmal nocturnal hemoglobinuria (PNH) is a form of acquired hemolytic anemia in which a defect of glycophosphatidylinositol anchor proteins in the cell membrane of bone marrow stem cells leads to activation of the complement system and consequent destruction of defective cells. The characteristics of this disease are an increased frequency of thrombotic events, anemia, and thrombocytopenia.

METHODS

We report a case of a pregnant patient with PNH with thrombocytopenia who delivered vaginally after receiving epidural labor analgesia. Prophylaxis of thromboembolism was performed with heparin 1 hour after the removal of the epidural catheter, and repeated at 12-hour intervals. Sensory changes or motor changes and pain were monitored every 10 minutes for 8 hours after delivery.

RESULTS

During analgesia, the patient reported complete pain relief. Delivery and the immediate postpartum period were without any untoward events.

CONCLUSIONS

Four major factors influenced the anesthetic conduct used for the present patient: (1) the risk of an acute hemolytic crisis, (2) the need to perform prophylaxis for thromboembolism, (3) the need to reduce labor stress, and (4) minimizing the risk of missing an epidural hematoma. We also present a survey of the literature about PNH and discuss the anesthetic conduct in this patient.

Analgesic and adverse effects of a low dose of intrathecally administered hyperbaric neostigmine alone or combined with morphine in patients submitted to spinal anaesthesia: pilot studies

We report the analgesic and adverse effects of intrathecally administered hyperbaric neostigmine, alone or combined with morphine, in two patients suffering from severe lower limb ischaemic pain (group 1), five patients undergoing Caesarean section (group 2) and 19 patients scheduled for orthopaedic surgery (group 3) under spinal anaesthesia. These patients were enrolled in three pilot studies undertaken before the initiation of the planned controlled studies. Hyperbaric neostigmine (50 micrograms in glucose 8%) produced analgesia lasting more than 6 h in patients of group 1, but the effect was accompanied by episodes of vomiting. A lower dose of hyperbaric neostigmine (25 micrograms), alone (two patients) or combined with morphine (50 micrograms) (one patient) produced no discernible analgesic effect but was followed by severe nausea and vomiting within 15 min of intrathecal injection in patients of group 2. Two patients who received hyperbaric morphine (100 micrograms) had analgesia for more than 24 h and exhibited mild pruritus. In patients of group 3, hyperbaric neostigmine alone (25 micrograms) produced analgesia of shorter duration than neostigmine (25 micrograms) plus morphine (50 micrograms) or morphine (100 micrograms). Neostigmine alone or combined with morphine was associated with adverse events, mainly nausea and vomiting that lasted up to 9-12 in some patients. Other adverse events observed included anxiety, somnolence and involuntary defaecation. Most patients who received the combination of neostigmine and morphine exhibited more severe nausea, vomiting and somnolence. The low clinical efficacy of intrathecally administered neostigmine alone or in combination with morphine impairs the design of a double-blind protocol and might restrict the clinical usefulness of the drug combination.