Sleep apnea, defined as intermittent respiratory arrest during sleep, is associated with increased incidence of hypertension and peripheral vascular disease. Exposure of rodents to brief periods of intermittent hypercarbia/hypoxia (H-IH) during sleep mimics the cyclical hypoxia-normoxia of sleep apnea. Endothelin-1, an upstream activator of nuclear factor of activated T cells (NFAT), is increased during H-IH. Therefore, we hypothesized that NFATc3 is activated by H-IH and is required for H-IH-induced hypertension. Consistent with this hypothesis, we found that H-IH (20 brief exposures per hour to 5% O2-5% CO2 for 7 h/day) induces systemic hypertension in mice [mean arterial pressure (MAP) ϭ 97 Ϯ 2 vs. 124 Ϯ 2 mmHg, P Ͻ 0.05, n ϭ 5] and increases NFATc3 transcriptional activity in aorta and mesenteric arteries. Cyclosporin A, an NFAT inhibitor, and genetic ablation of NFATc3 [NFATc3 knockout (KO)] prevented NFAT activation. More importantly, H-IHinduced hypertension was attenuated in cyclosporin A-treated mice and prevented in NFATc3 KO mice. MAP was significantly elevated in wild-type mice (⌬ ϭ 23.5 Ϯ 6.1 mmHg), but not in KO mice (⌬ ϭ Ϫ3.9 Ϯ 5.7). These results indicate that H-IH-induced increases in MAP require NFATc3 and that NFATc3 may contribute to the vascular changes associated with H-IH-induced hypertension.nuclear factor of activated T cells; hypercarbic; mouse; endothelin-1; sleep apnea SLEEP APNEA (SA), defined as intermittent respiratory arrest during sleep, affects up to 20% of the adult population. Among the major consequences of SA are decreased O 2 saturation (hypoxia) and increased CO 2 saturation (hypercapnia). In SA patients, incidence of hypertension, peripheral vascular disease, stroke, and sudden cardiac death is increased (for review see Refs. 21 and 44). Thus SA appears to directly initiate vascular changes that predispose individuals to cardiovascular disease.Recently, it was demonstrated that exposure of rodents to periods of intermittent hypoxia with CO 2 supplementation [intermittent hypercarbia/hypoxia (H-IH)] during sleep mimics the cyclical hypoxia-normoxia of SA. In rats exposed to H-IH, blood pressure (34, 35) and circulating endothelin-1 (ET-1) are elevated (35), vasoconstrictor sensitivity to ET-1 is increased (2), and blood pressure is normalized with ET antagonists (35). These studies, together with clinical studies showing increased circulating ET-1 in SA (10, 55), suggest that augmented ET-1 vasoconstriction contributes to SA hypertension. The sustained increased blood pressure observed in SA patients and animal models also appears to involve activation of the sympathetic nervous and renin-angiotensin systems and diminished activity of nitric oxide synthase (for review see Refs. 44 and 52).ET-1 acts through G␣ q -coupled receptors as a Ca 2ϩ -mobilizing agent and as a potent activator of the nuclear factor of activated T cells (NFAT) (1, 25, 57). ANG II, glucose through UTP release, and ␣ 1 -adrenergic agonists are also potent stimuli of NFAT activation (1,25,27,46,57).NFAT...
We reported previously that simulating sleep apnea by exposing rats to eucapnic intermittent hypoxia (E-IH) causes endothelin-dependent hypertension and increases constrictor sensitivity to endothelin-1 (ET-1). In addition, augmented ET-1-induced constriction in small mesenteric arteries (sMA) is mediated by increased Ca(2+) sensitization independent of Rho-associated kinase. We hypothesized that exposing rats to E-IH augments ET-1-mediated vasoconstriction by increasing protein kinase C (PKC)-dependent Ca(2+) sensitization. In sMA, the nonselective PKC inhibitor GF-109203x (3 microM) significantly inhibited ET-1-stimulated constriction in E-IH arteries but did not affect ET-1-stimulated constriction in sham arteries. Phospholipase C inhibitor U-73122 (1 microM) also inhibited constriction by ET-1 in E-IH but not sham sMA. In contrast, the classical PKC (cPKC) inhibitor Gö-6976 (1 microM) had no effect on ET-1-mediated vasoconstriction in either group, but a PKCdelta-selective inhibitor (rottlerin, 3 microM) significantly decreased ET-1-mediated constriction in E-IH but not in sham sMA. ET-1 increased PKCdelta phosphorylation in E-IH but not sham sMA. In contrast, ET-1 constriction in thoracic aorta from both sham and E-IH rats was inhibited by Gö-6976 but not by rottlerin. These observations support our hypothesis that E-IH exposure significantly increases ET-1-mediated constriction of sMA through PKCdelta activation and modestly augments ET-1 contraction in thoracic aorta through activation of one or more cPKC isoforms. Therefore, upregulation of a PKC pathway may contribute to elevated ET-1-dependent vascular resistance in this model of hypertension.
Background: Epidural analgesia is considered optimal for postoperative pain management after major abdominal surgery. The potential to decrease anesthetic and opioid exposure is particularly desirable for infants, given their vulnerability to respiratory depression and concern for anesthetic neurotoxicity. We reviewed our experience with infants undergoing major abdominal surgery to determine if epidural catheter use decreased anesthetic and opioid exposure and improved postoperative analgesia. Methods: This retrospective cohort study included infants (<12 months) who underwent exploratory laparotomy, ureteral reimplantation, or bladder exstrophy repair between November 2011 and November 2014. Primary outcomes of anesthetic exposure (mean endtidal sevoflurane) and intraoperative opioid administration were compared between infants who received epidural catheters and those who did not. Secondary outcomes included postoperative pain and sedation scores and morphine equivalents administered 0-24 and 24-48 hours after surgery. Results: Of 158 eligible infants, 82 were included and 47 received epidurals. Patients with epidurals underwent bladder exstrophy repair (N = 9), ureteral reimplantation (N = 8), and exploratory laparotomy (N = 30). Infants with epidurals received less intraoperative fentanyl (2.6 mcg/kg (0,4.5) vs 3.3 mcg/kg (2.4,5.8), P = 0.019) and morphine (6% (3/47) vs 26% (9/35), P = 0.014) in univariate analysis. After controlling for age and emergency surgery, differences in long-acting opioid administration persisted, with significantly less morphine given in the epidural group (OR 0.181; 95% CI 0.035-0.925; P = 0.040). Mean endtidal sevoflurane concentrations were similar between groups. There was no significant difference in postoperative median morphine equivalents. Conclusion: Placement of epidural catheters in infants undergoing major abdominal surgery is associated with decreased long-acting opioid requirements intraoperatively. Epidural placement does not preclude opioid exposure however, as opioids may be administered for indications other than nociceptive pain in the difficult-to-assess postoperative infant. Further prospective studies are warranted to better quantify the effect of epidural analgesia on intraoperative anesthetic exposure in infants. K E Y W O R D S opioids, pain, infant, regional
Vascular alpha(2B)-adrenoceptors (alpha(2B)-AR) may mediate vasoconstriction and contribute to the development of hypertension. Therefore, we hypothesized that blood pressure would not increase as much in mice with mutated alpha(2B)-AR as in wild-type (WT) mice following nitric oxide (NO) synthase (NOS) inhibition with N(omega)-nitro-l-arginine (l-NNA, 250 mg/l in drinking water). Mean arterial pressure (MAP) was recorded in heterozygous (HET) alpha(2B)-AR knockout mice and WT littermates using telemetry devices for 7 control and 14 l-NNA treatment days. MAP in HET mice was increased significantly on treatment days 1 and 4 to 14, whereas MAP did not change in WT mice (days 0 and 14 = 113 +/- 3 and 114 +/- 4 mmHg in WT, 108 +/- 0.3 and 135 +/- 13 mmHg in HET, P < 0.05). MAP was significantly higher in HET than in WT mice days 10 through 14 (P < 0.05). Thus blood pressure increased more rather than less in mice with decreased alpha(2B)-AR expression. We therefore examined constrictor responses to phenylephrine (PE, 10(-9) to 10(-4) M) with and without NOS inhibition to determine basal NO contributions to arterial tone. In small pressurized mesenteric arteries (inner diameter = 177 +/- 5 microm), PE constriction was decreased in untreated HET arteries compared with WT (P < 0.05). l-NNA (100 microM) augmented PE constriction more in HET arteries than in WT arteries, and responses were not different between groups in the presence of l-NNA. Acetylcholine dilated preconstricted arteries from HET mice more than arteries from WT mice. Endothelial NOS expression was increased in HET compared with WT mesenteric arteries by Western analysis. Griess assay showed increased NO(x) concentrations in HET plasma compared with those in WT plasma. These data demonstrate that diminished alpha(2B)-AR expression increases the dependence of arterial pressure and vascular tone on NO production and that vascular alpha(2B)-AR either directly or indirectly regulates vascular endothelial NOS function.
Renal dysfunction before and after orthotopic liver transplantation (OLT) has significant implications for morbidity and mortality of these patients. We describe the management of a 72-year-old male patient with history of alcoholic liver cirrhosis (MELD 38) undergoing OLT. The patient presented with declining renal function prior to OLT (baseline GFR ,25 mL/min) due to diuretic therapy for refractory ascites, hypovolemia postgastrointestinal bleed, and possible hepatorenal syndrome. The intraoperative management was complicated by preexisting anemia (hematocrit, 22%), unusual RBC antibody (anti-JKa) and significant surgical blood loss. To achieve surgical hemostasis, temporary clamping of the inferior vena cava (IVC) caudal to the transplanted liver was necessary. Postoperatively, the patient remained anuric despite appropriate fluid resuscitation. Renal replacement therapy was initiated to balance volume and acid-base status. A venogram on postoperative day (POD) 5 indicated a complete IVC occlusion and caval thrombectomy was performed on POD 6. After restoration of venous renal drainage, renal function improved and renal replacement therapy was weaned. Renal function indicators normalized in 8 weeks, and remained unimpaired up to 3 months post-OLT. Unintended complete obstruction of the suprarenal IVC may occur during OLT to control surgical bleeding, and should be considered as a cause for acute renal failure after liver transplant. Despite the preexisting renal dysfunction, renal function quickly improved after restoration of blood flow drainage and normalized in less than 8 weeks post obstruction.
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