Changes in nutritional status and the development of obesity and metabolic syndrome following pediatric heart transplantation.

BACKGROUND: Nutritional status in pediatric patients undergoing heart transplantation (HT) is frequently a focus of clinical management and requires high resource utilization. Pre-operative nutrition status has been shown to affect post-operative mortality but no studies have been performed to assess how nutritional status may change and the risk of developing nutritional comorbidities long-term in the post-transplant period. METHODS: A single-center retrospective chart review of patients ≥2 years of age who underwent heart transplantation between 1/1/2005 and 4/30/2020 was performed. Patient data were collected at listing, time of transplant, 1-year, and 3-year follow-up post-transplant. Nutrition status was classified based on body mass index (BMI) percentile in the primary analysis. Alternative nutritional indices, namely the nutrition risk index (NRI), prognostic nutrition index (PNI), and BMI z-score, were utilized in secondary analyses. RESULTS: Of the 63 patients included, the proportion of patients with overweight/obese status increased from 21% at listing to 41% at 3-year follow-up. No underweight patients at listing became overweight/obese at follow-up. Of patients who were overweight/obese at listing, 88% maintained that status at 3-year follow-up. Overweight/obese status at listing, 1-year, and 3-year post-transplantation were significantly associated with developing metabolic syndrome. In comparison to the alternative nutritional indices, BMI percentile best predicted post-transplant metabolic syndrome. CONCLUSIONS: The results suggest that pediatric patients who undergo heart transplantation are at risk of developing overweight/obesity and related nutritional sequelae (ie, metabolic syndrome). Improved surveillance and interventions targeted toward overweight/obese HT patients should be investigated to reduce the burden of associated comorbidities.

Epigenetic modifications of the glucocorticoid receptor gene are associated with the vulnerability to psychopathology in childhood maltreatment.

Stress, particularly when experienced early in life, can have profound implications for mental health. Previous research covering various tissues such as the brain, suggests that the detrimental impact of early-life stress (ELS) on mental health is mediated via epigenetic modifications including DNA methylation. Genes of the hypothalamic-pituitary-adrenal axis--in particular, the glucocorticoid receptor (hGR) gene--stand out as key targets for ELS. Even though the link between hGR methylation and either ELS or psychopathology is fairly well established, the mutually dependent relationships between ELS, DNA methylation and psychopathology remain to be uncovered. The specific psychopathology an individual might develop in the aftermath of stressful events can be highly variable, however, most studies investigating hGR methylation and psychopathology suffer from being limited to a single symptom cluster of mental disorders. Here, we screened volunteers for childhood maltreatment and analyzed whether it associates with hGR methylation in lymphocytes and a range of measures of psychological ill-health. hGR methylation in lymphocytes most likely reflects methylation patterns found in the brain and thus provides valuable insights into the etiology of psychopathology. We find the interaction between childhood maltreatment and hGR methylation to be strongly correlated with an increased vulnerability to psychopathology providing evidence of epigenome × environment interactions. Furthermore, our results indicate an additive effect of childhood maltreatment and hGR methylation in predicting borderline personality disorder (BPD)-associated symptoms, suggesting that the combination of both ELS and DNA methylation that possibly represents unfavorable events experienced even earlier in life poses the risk for BPD.

A prototype system for measuring microwave frequency reflections from the breast.

Microwave imaging of the breast is of interest for monitoring breast health, and approaches to active microwave imaging include tomography and radar-based methods. While the literature contains a growing body of work related to microwave breast imaging, there are only a few prototype systems that have been used to collect data from humans. In this paper, a prototype system for monostatic radar-based imaging that has been used in an initial study measuring reflections from volunteers is discussed. The performance of the system is explored by examining the mechanical positioning of sensor, as well as microwave measurement sensitivity. To gain insight into the measurement of reflected signals, simulations and measurements of a simple phantom are compared and discussed in relation to system sensitivity. Finally, a successful scan of a volunteer is described.

Human platelet Ca2+ mobilization, glycoprotein IIb/IIIa activation, and experimental coronary thrombosis in vivo in dogs are all inhibited by the inotropic agent amrinone.

BACKGROUND: Inotropic drugs are often used to treat acute, severe heart failure resulting from acute myocardial infarction and other unstable coronary artery syndromes. However, catecholamine inotropic agents may potentiate coronary thrombosis via a platelet alpha2-adrenergic mechanism, thus exacerbating the original problem. The present studies were designed to determine whether the nonadrenergic inotropic and vasodilator drug amrinone, which elevates platelet cAMP levels, would both inhibit human platelet Ca2+ mobilization and adhesion molecule expression ex vivo and protect against experimental coronary thrombosis in vivo in dogs. METHODS AND RESULTS: Human platelets in suspension were preincubated with amrinone 2.5 to 15 microg/mL; stimulated with the agonists thrombin 0.1 U/mL, ADP 10(-6) mol/L, or arginine vasopressin 10(7) mol/L; and studied for Ca2+ mobilization, glycoprotein IIb/IIIa activation, and P-selectin expression by fluorescent flow cytometry methods. Experimental coronary thrombosis in vivo was studied in an open-chest dog model with critical coronary artery stenosis and deep vessel wall injury. Results showed that at the cellular level, amrinone inhibited agonist-induced Ca2+ mobilization and had modest inhibitory effects on adhesion molecule expression. In vivo in dogs, intravenous amrinone 2 mg/kg plus infusion at 20 microg x kg(1) x min(-1) completely abolished coronary thrombosis. CONCLUSIONS: The fact that amrinone inhibited human platelet activation at the cellular level and protected against experimental coronary thrombosis in vivo in dogs suggests a potentially advantageous antithrombotic action for this inotropic and vasodilator drug.

The effect of the neurolytic agent ethanol on cytoplasmic calcium in arterial smooth muscle and endothelium.

BACKGROUND AND OBJECTIVES: Celiac plexus neurolysis, although effective in relieving pain associated with upper abdominal malignancy, occasionally results in paraplegia. Diffusion of the neurolytic agent to arteries supplying the spinal cord has been postulated as a cause, and previous studies with isolated lumbar segmental arteries have demonstrated contraction in response to ethanol and phenol. The mechanism of this contractile effect is unknown, but a role for insular free calcium (Ca2+i) is suggested by the known involvement of Ca2+i in both smooth muscle vasoconstriction and toxic cell injury. The authors sought to determine whether nontoxic concentrations of ethanol cause a direct elevation of Ca2+i in arterial smooth muscle and endothelium. METHODS: Primary cultures of human aortic smooth muscle and endothelial cells were studied to determine the direct effect of ethanol independent of interactions with agonists or contractile proteins. Ca2+i levels were determined in single cells with digitized video fluorescence microscopy, using ratio imaging of the Ca2+i-sensitive fluorophore fura-2. RESULTS: In aortic smooth muscle cells, initial Ca2+i was 98 +/- 41 nM (n = 59 cells). Histamine (10 microM) as a positive control caused an increase in Ca2+i, as expected. Ethanol alone, at doses of 2-5% (v/v) also caused a sustained elevation in Ca2+i of physiologically significant magnitude. Ethanol at doses of 5% or lower did not cause any visibly apparent injury within 30 minutes. In contrast, 10% or higher ethanol doses quickly caused membrane blebbing, a sign of toxic injury, followed by cell death within 20 minutes. Aortic endothelial cells were more resistant to ethanol than smooth muscle cells, in terms of both Ca2+i elevation and cell death. CONCLUSIONS: Ethanol, even at nontoxic concentrations, has a direct effect on aortic smooth muscle Ca2+i, large enough to be associated with significant vasoconstriction. The findings suggest a possible role for pharmacologic agents that preserve Ca2+i homeostasis in protecting against neurolysis-induced paraplegia, although additional study is required before clinical application is appropriate.

Effect of volatile anesthetics on hydrogen peroxide-induced injury in aortic and pulmonary arterial endothelial cells.

BACKGROUND: Oxidant damage to endothelial cells occurs during inflammation and reperfusion after ischemia, mediated in part by endogenously produced hydrogen peroxide (H2O2). Previous studies have established a role for increased cytosolic calcium in the mechanism of endothelial oxidant injury, and have suggested that volatile anesthetics may exacerbate oxidant injury in pulmonary endothelium. However, the effect of volatile anesthetics on oxidant injury to systemic arterial endothelial cells, and their effect on oxidant-related changes in cytosolic calcium homeostasis, have not been reported previously. METHODS: Primary cultures of human aortic and pulmonary arterial endothelial cells were studied. The rate of cell death after H2O2 exposure was determined in cell suspension by propidium iodide fluorimetry and lactate dehydrogenase release. The final extent of cell death 24 h after H2O2 exposure was determined in monolayer cultures by methyl thiazolyl tetrazolium reduction. Cytosolic calcium and cell death were determined in single cells using fura-2 and propidium iodide imaging with digitized, multiparameter, fluorescent video microscopy. RESULTS: In aortic endothelial cells, clinical concentrations of halothane (1.0%) and isoflurane (1.5%) decreased both the rate of cell death and the final extent of cell death after H2O2 exposure, with halothane being more protective. Supraclinical concentrations of halothane (2.7%) and isoflurane (4.0%) were less protective. In pulmonary arterial endothelial cells, halothane and isoflurane had essentially no effect on H2O2-mediated cell death. The protective effect of anesthetic in aortic endothelial cells was not due to an enhanced removal of H2O2 by endogenous enzymes. Hydrogen peroxide exposure caused a large increase in cytosolic calcium well before cell death, and this was moderated by anesthetic treatment. CONCLUSIONS: The effect of volatile anesthetics on oxidant injury to endothelial cells may differ between cells derived from systemic and pulmonary vascular beds. Halothane, and to a lesser extent, isoflurane, protects against oxidant injury in aortic endothelial cells. The mechanism of protection may involve modulation of the interaction of H2O2 with vital cellular constituents, and/or amelioration of the toxic increase in cytosolic calcium that follows such interaction.

Cytosolic free calcium and cell death during metabolic inhibition in a neuronal cell line.

Elevated free cytosolic Ca2+ (Ca2+i) has been implicated as a mechanism of hypoxic neuronal death. The calcium hypothesis postulates that the basic metabolic response to hypoxic ATP depletion is a toxic increase in free cytosolic Ca2+i in all cell types. This inherent response then creates the environment in which subsequent derangements of Ca2+i may occur, for example, from glutamate excitotoxicity. Although the effect of glutamate on neuronal Ca2+i has been extensively studied, the basic neuronal response to hypoxia independent of glutamate receptor activation is not well defined. We therefore assayed both Ca2+i and plasma membrane integrity in fura-2-loaded, single SK-N-SH neuroblastoma cells, using digitized video microscopy and metabolic inhibition (2.5 mM NaCN, 10 mM 2-deoxyglucose) to model the ATP depletion of hypoxia. Median time to cell death was 90 min (n = 51 cells). Initial Ca2+i was 121 +/- 67 nM. Ca2+i increased by 50 nM after 5-10 min of metabolic inhibition. Blebbing of the cell membrane was evident within 30 min. Ca2+i did not appreciably increase further until the time of cell death, when the loss of plasma membrane integrity allowed unimpeded influx of extracellular Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Volatile anesthetics and agonist-induced contractions in porcine coronary artery smooth muscle and Ca2+ mobilization in cultured immortalized vascular smooth muscle cells.

BACKGROUND: These experiments addressed four specific questions. Do isoflurane and halothane (0.5-3.0% in the gas phase) inhibit contractions evoked in isolated porcine coronary artery rings (without endothelium) by the specific Ca2+ mobilizing agonists serotonin, endothelin-1, and F-? Are contractions evoked by phorbol-activated protein kinase C inhibited by the anesthetics? In a well-characterized vascular smooth muscle cell culture model (A7r5 and A10), do the anesthetics attenuate serotonin- and endothelin-induced Ca2+ mobilization? Do the anesthetics inhibit intracellular Ca2+ mobilization via facilitated cAMP formation? METHODS: Tension was measured in rings suspended in organ chambers. Apparent intracellular Ca2+ was estimated in cells using indo-1 and flow cytometry. Cyclic AMP was measured by radioimmunoassay. RESULTS: At the anesthetic concentrations examined, isoflurane attenuated contractions evoked by serotonin and F- but not those induced by endothelin-1 or phorbol dibutyrate. In cells, isoflurane 2% attenuated 3 x 10(-5) M serotonin-induced Ca2+ mobilization by about 26%, whereas Ca2+ responses evoked by endothelin 10(-8) M were more resistant to anesthetic inhibitory effect. Halothane attenuated contractions in rings evoked by serotonin, endothelin, and F- but lacked effect on phorbol-induced responses. In cells, halothane 2% inhibited Ca2+ mobilization induced by serotonin by about 43% and that induced by endothelin by about 31%. Neither anesthetic facilitated cAMP formation. CONCLUSIONS: Isoflurane and halothane variably attenuated contractions evoked by Ca2+ mobilizing agonists--by a cellular action beyond the receptor level--but did not inhibit phorbol activated protein kinase C. Serotonin- and endothelin-induced Ca2+ mobilization was inhibited by isoflurane and halothane--but the mechanism does not depend upon increased cAMP.

Role of superoxide anions in the mediation of endothelium-dependent contractions.

We designed experiments to characterize the role of superoxide anions in the mediation of endothelium-dependent contractions in isolated canine basilar arteries. Rings with and without endothelium were suspended for isometric tension recording in Krebs-Ringer bicarbonate solution bubbled with 94% O2-6% CO2 (37 degrees C, pH 7.4). Radioimmunoassay was used to determine the levels of cyclic GMP and cyclic AMP. Calcium ionophore A23187 (10(-9) to 10(-6) mol/L) caused concentration-dependent contractions. The removal of endothelium abolished the effect of A23187. Contractions to A23187 were reversed into relaxations in the presence of superoxide dismutase (150 U/mL) or the prostaglandin H2/thromboxane A2 receptor antagonist SQ29548 (10(-6) mol/L). NG-nitro-L-arginine methyl ester (3 x 10(-4) mol/L) augmented contractions to A23187. In rings with endothelium, A23187 (3 x 10(-7) mol/L) significantly increased levels of both cyclic AMP and cyclic GMP. Indomethacin (10(-5) mol/L) inhibited stimulatory effects of A23187 on cyclic AMP production. In contrast, indomethacin augmented A23187-induced production of cyclic GMP. Selective augmentation of cyclic GMP production by indomethacin appears to be due to protection of nitric oxide or a closely related molecule released following translocation of calcium into endothelial cells. Our findings suggest that (1) an increased concentration of calcium in endothelial cells may activate both cyclooxygenase and the L-arginine/nitric oxide pathway, (2) arachidonic acid metabolism via cyclooxygenase is a source of superoxide anions, and (3) superoxide anions may be responsible for impairment of balance between relaxing and contracting factors leading to contraction of underlying smooth muscle cells.

Effect of halothane on hypoxic toxicity and glutathione status in cultured rat hepatocytes.

BACKGROUND: In hypoxic rats, halothane causes hepatotoxicity at oxygen levels that would cause minimal hepatotoxicity in the absence of halothane. Using a model that excludes systemic and extrahepatic effects of halothane, the authors tested the hypothesis that halothane hepatotoxicity in the whole-rat model is caused by a direct hepatotoxic effect of halothane, which is mediated by halothane-derived free radicals. METHODS: Rat hepatocyte monolayer cultures were exposed to defined gas phases for 2 h. Three experimental variables were present or absent: hypoxia (1% O2), halothane (2%), and cytochrome P-450 induction (by phenobarbital). Two experimental outcomes were measured: aspartate aminotransferase release, a measure of cell death, and reduced glutathione, an endogenous free radical scavenger whose levels are decreased by physiologically significant free radical injury. RESULTS: As anticipated, hypoxia increased cell death. Cytochrome P-450 induction by itself increased cell death during hypoxia. However, halothane had no effect on cell death during hypoxia, with or without cytochrome P-450 induction. Halothane had no toxic effect, even when glutathione was depleted before the onset of hypoxia. Glutathione was decreased moderately by hypoxia alone. Neither halothane nor cytochrome P-450 induction had any effect on glutathione levels. CONCLUSIONS: Halothane was not toxic, and it did not generate a physiologically significant free radical insult during hypoxia in the isolated rat hepatocyte under the experimental conditions used in testing.

Nitrous oxide constricts epicardial coronary arteries in pigs: evidence suggesting inhibitory effects on the endothelium.

Nitrous oxide increases peripheral vascular tone in animals and humans and constricts epicardial coronary arteries in dogs. Current studies sought both to determine whether nitrous oxide caused epicardial coronary artery constriction in a second animal species, pigs, and to investigate mechanisms. Left anterior descending coronary artery diameters were measured by using computer-assisted angiography in intact pigs anesthetized with ketamine and fentanyl. In separate experiments, isolated porcine coronary arteries were used to assess nitrous oxide effects on both vascular tone and norepinephrine overflow. Agonist-induced increases in [Ca2+]i were estimated in cultured porcine coronary endothelial cells. Nitrous oxide caused epicardial coronary artery vasoconstriction in vivo by about 20%. Nitrous oxide did not affect endothelium-dependent relaxations and contractions in isolated vessels. Norepinephrine overflow was increased but only in vessels with endothelium. The anesthetic attenuated Ca2+ mobilization in endothelial cells. We conclude that nitrous oxide induces epicardial coronary artery constriction in pigs and suggest that the mechanism may involve the inhibition of endothelium-dependent norepinephrine turnover.

High-dose droperidol protects against experimental coronary thrombosis in dogs and pigs and attenuates aggregation of porcine platelets and Ca2+ mobilization in human platelets.

BACKGROUND: Activation of platelets after contact with thrombogenic substrates may be an early factor leading to coronary artery thrombosis and myocardial infarction. Haloperidol, a butyrophenone, possesses weak in vitro platelet inhibitory activity. Experiments were designed to determine whether droperidol, a butyrophenone adjunct to anesthesia, protected against experimental coronary thrombosis in intravenously anesthetized open-chest dogs and pigs, attenuated ex vivo porcine platelet aggregation, and inhibited agonist-induced increases in [Ca2+]i in human platelets. METHODS: In dogs and pigs, a lesion consisting of deendothelialization, deep vessel wall injury, and critical stenosis was created in the proximal circumflex arteries, resulting in coronary thrombus formation accompanied by decreased circumflex artery blood flow. Embolization of the thrombus restored flow, but the cycle then repeated, resulting in repetitive cyclical flow reductions (CFRs). These were measured using an electromagnetic flow probe. RESULTS: In dogs, droperidol 0.2 mg/kg intravenous rapidly abolished CFRs in all ten animals, with frequency decreasing from 0.22 +/- 0.01 cycles/min to 0. Droperidol 0.8 mg/kg intravenous rapidly abolished CFRs in seven of eight pigs, with frequency decreasing from 0.15 +/- 0.01 to 0.02 cycles/min (P < 0.005). In both species, additional doses of droperidol were effective against CFRs augmented with intravenous epinephrine, a catecholamine that stimulates thrombosis. Ex vivo platelet aggregation studies were performed in platelet-rich plasma obtained from pigs before and after droperidol 0.8 mg/kg intravenous. Pretreatment with the drug resulted in marked inhibition of aggregation evoked by collagen, modest attenuation of that elicited by adenosine diphosphate (ADP), but no effect on that evoked by arachidonic acid. In human platelets, apparent [Ca2+]i was estimated using the fluorescent indicator indo-1 and flow cytometry. Droperidol 10(-7), 10(-6), and 10(-5)M had a dose-dependent inhibitory effect on the amplitude of increases in [Ca2+]i evoked by 10(-5)M serotonin (plus 10(-7)M epinephrine). The higher droperidol concentration decreased the response to as much as 30% of control (P < 0.001). Droperidol lacked effect on Ca2+ mobilization elicited with 10(-6)M ADP. CONCLUSIONS: The results from three experimental models indicate that droperidol attenuates experimental coronary thrombosis in animals and suggest that this inhibition may result, in part, from a direct droperidol depressant effect on platelet activation and aggregation.

The volatile anesthetic isoflurane attenuates Ca++ mobilization in cultured vascular smooth muscle cells.

Isoflurane is a volatile anesthetic which decreases vascular tone. Experiments were designed to determine whether isoflurane attenuated agonist-induced signaling in cultured vascular smooth muscle cells (A7r5). Cells were preincubated for 15 to 20 min with clinically relevant concentrations of isoflurane--0.5 to 2% in the gas phase and stimulated with 10(-9) or 10(-7) M vasopressin or with 3.3 x 10(-9) M platelet-derived growth factor. The two agonists are believed to act via differing signaling pathways. Total inositol phosphate formation was measured by column chromatography. Apparent intracellular free Ca++ concentration (1) [Ca++]i was estimated using indo-1 and flow cytometry. Isoflurane attenuated increases in [Ca++]i evoked by both agonists. Isoflurane 2.0% inhibited [Ca++]i responses evoked by vasopressin by 35 to 41%. Responses due to Ca++ release from intracellular stores were particularly sensitive to inhibition by isoflurane. The anesthetic attenuated inositol phosphate generation evoked by vasopressin and platelet-derived growth factor, suggesting a mechanism for isoflurane action on Ca++ release. Surprisingly, the anesthetic only modestly inhibited increases in [Ca++]i due to Ca++ entry. Isoflurane's effect on Ca++ influx after emptying of Ca++ stores was probed using thapsigargin. Inhibition of Ca++ influx was modest. It is suggested that isoflurane attenuates total inositol phosphate formation and Ca++ release evoked by vasopressin and platelet-derived growth factor while having limited effects on agonist-induced Ca++ entry.

Endothelial L-arginine pathway and relaxations to vasopressin in canine basilar artery.

Experiments were designed to determine the role of the L-arginine pathway in endothelium-dependent relaxations to vasopressin. The effects of L-arginine analogues NG-nitro-L-arginine (L-NNA), NG-nitro-L-arginine methyl ester (L-NAME), and NG-monomethyl-L-arginine (L-NMMA) on basal and vasopressin-induced activity of nitric oxide synthase were studied in isolated canine basilar arteries. Rings with and without endothelium were suspended for isometric tension recording in Krebs-Ringer bicarbonate solution bubbled with 94% O2-6% CO2 (37 degrees C, pH 7.4). Radioimmunoassay was used to determine the level of guanosine 3',5'-cyclic monophosphate (cGMP). All experiments were performed in the presence of indomethacin, a cyclooxygenase inhibitor. L-NAME and L-NMMA caused endothelium-dependent contractions and inhibited basal production of cGMP. In contrast, L-NNA did not affect basal tone or basal production of cGMP. L-Arginine analogues inhibited relaxations to vasopressin but did not affect relaxations to a nitric oxide donor, molsidomine (SIN-1). The effects of L-NNA, L-NAME, and L-NMMA were reversed in the presence of L-arginine. The relaxations to vasopressin were associated with an increase of cGMP levels in the arterial wall. This effect of vasopressin was inhibited in the presence of L-NNA. These studies suggest that the relaxations to vasopressin are mediated by activation of the endothelial L-arginine pathway, leading to increased production of nitric oxide, with subsequent activation of guanylate cyclase in smooth muscle cells. In canine basilar artery, L-NAME and L-NMMA are nonselective inhibitors of both basal and stimulated production of nitric oxide, whereas L-NNA selectively inhibits vasopressin-induced activation of the L-arginine pathway.

Halothane inhibits agonist-induced inositol phosphate and Ca2+ signaling in A7r5 cultured vascular smooth muscle cells.

Halothane, an anesthetic with marked depressant effects on the circulation, was studied for its ability to inhibit inositol phosphate and Ca2+ signaling evoked by the vasoactive hormone arginine vasopressin (AVP) and Ca2+ responses elicited by platelet-derived growth factor and by thapsigargin in cultured A7r5 vascular smooth muscle cells. Changes in apparent [Ca2+]i were measured using the indicator indo-1 and flow cytometry, whereas inositol phosphate levels were determined using myo-[3H]inositol and column chromatography. Preincubation with clinically relevant concentrations of halothane resulted in dose-dependent depression of [Ca2+]i responses evoked on stimulation with AVP. Halothane (2.0%) inhibited the increases in [Ca2+]i by 34-45%. In cells incubated in Ca(2+)-free medium plus 0.5 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, the halothane effect was more marked, with 1.5% halothane inhibiting the responses by approximately 53-61%. However, when Ca2+ influx was stimulated by addition of 5 mM Ca2+ in the continued presence of the agonist, the [Ca2+]i response was inhibited by only 15%, suggesting that release of Ca2+ rather than Ca2+ influx is more sensitive to inhibition by the anesthetic. The effects of halothane on Ca2+ homeostasis are not explained solely by anesthetic-induced depletion of Ca2+ from intracellular stores, because the anesthetic inhibited increases in [Ca2+]i elicited by thapsigargin in cells suspended in Ca(2+)-free medium by only 31%. Halothane inhibited inositol phosphate formation elicited by AVP, suggesting an additional means by which the anesthetic may alter agonist-induced Ca2+ responses. The current results also demonstrate that halothane actions are not specific solely to responses evoked by AVP, which acts via a guanine nucleotide-binding protein-linked signaling pathway, but include responses stimulated by platelet-derived growth factor, an agonist that elevates [Ca2+]i via receptor-latent tyrosine kinase activity. The current results demonstrate that, in vascular smooth muscle cells, halothane alters Ca2+ homeostasis, an action that may underlie the in vivo vasodilator effects of the anesthetic.

Halothane 1.5 MAC, isoflurane 1.5 MAC, and the contractile responses of coronary arteries obtained from human hearts.

Active vasoconstriction of epicardial coronary arteries can cause myocardial ischemia in patients with coronary artery disease. Relief of vasoconstriction can improve blood flow to the heart. The purpose of this study was to determine if 1.5 MAC halothane and 1.5 MAC isoflurane would each attenuate contractions evoked by three putative mediators of coronary constriction in coronary arteries removed from the hearts of human beings. Hearts were obtained in the operating room from five patients undergoing cardiac transplantation and from six brain-dead patients undergoing organ donation procedures. Coronary arteries were dissected free, cut into rings, and studied in organ chambers. Endothelium-dependent relaxations to 10(-6) M bradykinin were examined; they indicated a variable degree of endothelial dysfunction in vessels used in the experiments. Contractile responses to 40 mM KCl were tested and were used as control contractions. Contractions evoked by serotonin, histamine, and prostaglandin F2 alpha were measured and were expressed as a percent of contractile responses evoked by 40 mM KCl. Halothane depressed the agonist-induced contractions. Maximal contractile responses to serotonin were 130% +/- 28% in untreated rings and 63% +/- 10% in rings exposed to halothane (P less than 0.03). Responses to histamine were 183% +/- 46% untreated and 121% +/- 26% during halothane administration (P less than 0.05), and responses to prostaglandin F2 alpha were 227% +/- 42% untreated and 148% +/- 18% with halothane (P less than 0.05). Isoflurane had no effect on contractions. The results demonstrate that 1.5 MAC halothane, but not 1.5 MAC isoflurane, attenuates contractile responses evoked by putative mediators of coronary vasoconstriction in coronary arteries removed from the hearts of human beings.

Attenuation of contraction of isolated canine coronary arteries by enflurane and halothane.

Contraction of vascular smooth muscle such as that existing in coronary arteries is regulated in part by Ca++ entry into cells via Ca++ channels. Volatile anaesthetics are known to attenuate agonist-induced coronary artery constriction. The purpose of this experiment was to determine if 1.5 MAC concentrations of halothane or enflurane attenuated contractions evoked by activation of one type of Ca++ channel--the potential operator channel. In the current experiment, potential operator channels were activated by depolarizing isolated canine coronary artery rings with high concentration of K+, causing Ca++ entry and vessel contraction. Rings without endothelium were suspended for isometric force measurement in organ chambers containing aerated Krebs-Ringer solution. Maximum response to Ca++ in rings depolarized with K+ was 120 +/- 5 per cent in untreated versus 101 +/- 3 per cent in rings treated with enflurane (P less than 0.01). The maximum response was 123 +/- 6 per cent in untreated versus 111 +/- 5 per cent during halothane administration (P less than 0.05). In contrast, nifedipine 10(-9) M depressed maximum contractions from 114 +/- 5 per cent to 37 +/- 4 per cent (P less than 0.01) and nifedipine 10(-8) M depressed contractions to 30 +/- 4 per cent (P less than 0.01). In a further series of experiments, sustained contractions were depressed by continued administration of the anaesthetics, indicating no loss of anaesthetic effect with time. The results indicate that 1.5 MAC halothane and enflurane attenuate contractions of canine coronary arteries evoked by depolarization and Ca++ entry through potential operated channels. However, neither halothane nor enflurane exhibited the marked depressant effect exerted by nifedipine.

Isoflurane and halothane attenuate coronary artery constriction evoked by serotonin in isolated porcine vessels and in intact pigs.

Serotonin is a vasoconstrictor thought to cause coronary artery constriction in humans. The purpose of this study was to determine if isoflurane and halothane each attenuated coronary artery constriction evoked by serotonin in pigs. Both in vitro and in vivo experimental methods were used. Isolated coronary arteries with an without endothelium were studied in organ chambers in the presence and absence of 2.5% concentrations of the anesthetics. In intact pigs serotonin was infused directly into the left anterior descending coronary arteries to induce constriction. The vasodilator effects of 0.5%, 1.25%, and 2.0% isoflurane and halothane were determined using quantitative angiography. Contractile responses of isolated coronary arteries were depressed by the two anesthetics. Maximum contractile responses to serotonin were as follows: rings with endothelium 45 +/- 5% untreated versus 29 +/- 5% with isoflurane 2.5% (difference between dose-response curves, P less than 0.01) and without endothelium 67 +/- 5% untreated versus 51 +/- 6% with isoflurane 2.5% (P less than 0.001); with endothelium 52 +/- 7% untreated versus 28 +/- 7% with halothane 2.5% (P less than 0.001) and without endothelium 65 +/- 5% untreated versus 40 +/- 6% with halothane 2.5% (P less than 0.001). In intact pigs isoflurane and halothane dilated constricted coronary arteries with and without endothelium at all anesthetic concentrations tested, including concentrations as low as 0.5%. Isoflurane 1.25% increased diameter of vessels with endothelium from 1.5 +/- 0.1 mm to 1.7 +/- 0.1 mm (P less than 0.02) and halothane 1.25% increased diameter from 1.6 +/- 0.1 mm to 1.7 +/- 0.1 mm (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Fentanyl is devoid of major effects on coronary vasoreactivity and myocardial metabolism in experimental animals.

Experiments were designed to determine the effects of fentanyl on coronary vascular tone and energetic state of the heart. Both arterial and arteriolar responses were assessed; particular attention was directed to epicardial vessels. Four experimental methods and three animal species were used. Isolated canine coronary artery rings with and without endothelium were suspended in organ chambers, and changes in their tension were measured. Fentanyl (100 ng/ml) had no effect on resting tension of unstimulated rings on a contraction evoked by serotonin 10(-8) to 10(-4) M. In rings with endothelium, the opioid had a minimal depressant effect on the contractile response to phenylephrine. Tension of vessels precontracted with serotonin (3 x 10(-7) M), or phenylephrine (10(-5) M) was unchanged following fentanyl at 10, 30, 70, or 150 ng/ml. Computerized quantitative angiography was used in intact pigs anesthetized with ketamine to determine the effects of fentanyl on coronary artery diameters of vessels with or without endothelium. Intravenous fentanyl 50 and 250 micrograms/kg had no effect on vessel diameters. Isolated perfused rat hearts were used to assess fentanyl effects upon coronary flow and arteriolar tone and upon myocardial energy state. Coronary blood flow was not altered by fentanyl (100 ng/ml) and was unchanged following washout of the drug. The heart maintained a normal energy status prior to and following fentanyl treatment. These data demonstrate that, under the conditions tested, fentanyl is devoid of major effects on the coronary circulation and upon myocardial metabolism.