Low Concentrations Of Epinephrine Research Articles

Blood concentrations of brain natriuretic peptide (Nt-pro-BNP) and the regulation of hemodynamic reactions in healthy adult Arctic residents

BACKGROUND: In previous studies, we have observed that the levels of Nt-pro-BNP in healthy individuals are lower than among patients with coronary heart disease and hypertension. Additionally, Nt-pro-BNP concentration increases with age. Interestingly, Arctic residents have higher levels of Nt-pro-BNP compared to those living in other northern territories.
 AIM: To study the role of Nt-pro-BNP in the regulation of hemodynamic reactions in adults residing in the Arctic.
 MATERIALS AND METHODS: In total, 111 healthy adults (66 women and 45 men) aged 4655 years living and working on Svalbard, and in the Murmansk region comprised the study group. The comparison group included 118 healthy adults of the same age from the Arkhangelsk region (59 women and 59 men). Peripheral venous blood samples were taken. Hemogram and concentrations of CD3+, CD4+, CD8+, CD10+, CD16+, CD19+, CD23+, CD25+, CD71+ lymphocytes were studied by an indirect immunoperoxidase reaction and a flow cytometry. Blood concentrations of Nt-pro-BNP, endothelin-1, total NO, endogenous NO2, nitrate NO3, cortisol, norepinephrine, epinephrine were assessed using enzyme immunoassay. Data were presented as means and standard errors of the mean (Mm). Depending on the distribution, unpaired t-tests or MannWhitney U-tests were used for all comparisons.
 RESULTS: Blood concentration of Nt-pro-BNP was higher in the Arctic residents compared with those living in Arkhangelsk. Elevated concentrations of Nt-pro-BNP in the Arctic residents were associated with higher levels of norepinephrine and cortisol and lower concentrations of epinephrine and endothelin-1. Moreover, we observed a re-distribution of lymphocytes and monocytes from the circulating to the marginal pool. These features of the hemodynamic reaction were more pronounced among the Arctic residents and among women in all settings.
 CONCLUSION: The effect of natriuretic peptide is associated with simultaneous activation of the concurrent activation of norepinephrine and cortisol secretion, which poses a risk of disrupting the body's mechanisms for maintaining a narrow range of osmolarity in the internal environment.

DNA Polymorphisms in Pregnant Women with Sticky Platelet Syndrome.

Sticky platelet syndrome (SPS) is a thrombophilia caused by the increased aggregability of platelets in response to the addition of low concentrations of epinephrine (EPI) and/or adenosine diphosphate (ADP). Some of the single nucleotide polymorphisms (SNP), alleles and haplotypes of platelet glycoprotein receptors were proved to have a role in the etiology of thrombotic episodes When comparing SPS and the control group, in VEGFA rs3025039, the p value for both CC vs. TT and CT vs. TT analyses was <0.001. Interestingly, no minor TT genotype was present in the SPS group, suggesting the thrombotic pathogenesis of recurrent spontaneous abortions (RSA) in these patients. Moreover, we found a significant difference in the presence of AT containing a risky A allele and TT genotype of ALPP rs13026692 (p = 0.034) in SPS patients when compared with the controls. Additionally, we detected a decreased frequency of the GG (CC) genotype of FOXP3 rs3761548 in patients with SPS and RSA when compared with the control group (p value for the CC (GG) vs. AA (TT) 0.021). This might indicate an evolutionary protective mechanism of the A (T) allele in the SPS group against thrombotic complications in pregnancy. These results can be used for antithrombotic management in such pregnant patients.

Alpha and beta adrenergic receptors modulate keratinocyte migration.

Keratinocyte migration into skin wounds is the step of the healing process that correlates with the wound closure rate. Keratinocyte migration, and wound epithelialization are decreased when beta 2-adrenergic receptors (B2AR) are activated by 1 μM epinephrine/adrenaline, resulting in delayed wound healing in human and mouse skin. In the present study, we found paradoxically, that in a subset of keratinocyte strains exposure to low concentrations of epinephrine (0.1 nM) increased, rather than decreased, their migratory rate. We find that both the alpha- and the beta-adrenergic receptors are expressed in human keratinocytes, and expression of alpha-2 AR subtypes demonstrated for the first time. Therefore, we tested if the alpha-AR could be modulating the increased migratory response observed in these cell strains. By using specific inhibitors to alpha-AR, we demonstrated that blocking A2B-AR could reverse the rapid cell migration induced by the 0.1 nM epinephrine. Phosphorylation of ERK was elevated after 1–10 minutes of the low epinephrine treatment and the A2B-AR inhibitor blocked the ERK phosphorylation. The results suggest that both the A2B-AR and B2AR mediate keratinocyte migration, in which with a low level of epinephrine treatment, A2B-AR could alter the B2AR signals and regulate the migration rate.

Arrhythmogenic Interaction Between Sympathetic Tone and Mechanical Stretch in Rat Pulmonary Vein Myocardium.

Rapid firing from pulmonary veins (PVs) frequently initiates atrial fibrillation, which is a common comorbidity associated with hypertension, heart failure, and valvular disease, i.e., conditions that pathologically increase cardiomyocyte stretch. Autonomic tone plays a crucial role in PV arrhythmogenesis, while its interplay with myocardium stretch remains uncertain. Two-microelectrode technique was used to characterize electrophysiological response of Wistar rat PV to adrenaline at baseline and under mild (150 mg of applied weight that corresponds to a pulmonary venous pressure of 1 mmHg) and moderate (10 g, ∼26 mmHg) stretch. Low concentrations of adrenaline (25–100 nmol/L) depolarized the resting membrane potential selectively within distal PV (by 26 ± 2 mV at baseline, by 18 ± 1 mV at 150 mg, P < 0.001, and by 5.9 ± 1.1 mV at 10 g, P < 0.01) suppressing action potential amplitude and resulting in intra-PV conduction dissociation and rare episodes of spontaneous activity (arrhythmia index of 0.4 ± 0.2, NS vs. no activity at baseline). In contrast, 1–10 μmol/L of adrenaline recovered intra-PV propagation. While mild stretch did not affect PV electrophysiology at baseline, moderate stretch depolarized the resting potential within distal PV (-56 ± 2 mV vs. -82 ± 1 mV at baseline, P < 0.01), facilitated the triggering of rapid PV firing by adrenaline (arrhythmia index: 4.4 ± 0.2 vs. 1.3 ± 0.4 in unstretched, P < 0.001, and 1.7 ± 0.8 in mildly stretched preparations, P < 0.005, at 10 μmol/L adrenaline) and induced frequent episodes of potentially arrhythmogenic atrial “echo” extra beats. Our findings demonstrate complex interactions between the sympathetic tone and mechanical stretch in the development of arrhythmogenic activity within PVs that may impact an increased atrial fibrillation vulnerability in patients with elevated blood pressure.

Effect of Coagulation Factor Concentrates on Markers of Endothelial Cell Damage in Experimental Hemorrhagic Shock.

Plasma-based resuscitation showed protective effects on the endothelial glycocalyx compared with crystalloid resuscitation. There is paucity of data regarding the effect of coagulation factor concentrates (CFC) on the glycocalyx in hemorrhagic shock (HS). We hypothesized that colloid-based resuscitation supplemented with CFCs offers a therapeutic value to treat endothelial damage following HS. Eighty-four rats were subjected to pressure-controlled (mean arterial pressure (MAP) 30-35 mm Hg) and lab-guided (targeted cutoff: lactate >2.2. mmol/L and base deficit > 5.5 mmol/L) HS. Animals were resuscitated with fresh frozen plasma (FFP), human albumin (HA) or Ringer's lactate (RL) and RL or HA supplemented with fibrinogen concentrate (FC) or prothrombin complex concentrate (PCC). Serum epinephrine and the following markers of endothelial damage were assessed at baseline and at the end-of-observation (120 min after shock was terminated): syndecan-1, heparan sulfate, and soluble vascular endothelial growth factor receptor 1 (sVEGFR 1). Resuscitation with FFP had no effect on sVEGFR1 compared with crystalloid-based resuscitation (FFP: 19.3 ng/mL vs. RL: 15.9 ng/mL; RL+FC: 19.7 ng/mL; RL+PCC: 18.9 ng/mL; n.s.). At the end-of-observation, syndecan-1 was similar among all groups. Interestingly, HA+FC treated animals displayed the highest syndecan-1 concentration (12.07 ng/mL). Resuscitation with FFP restored heparan sulfate back to baseline (baseline: 36 ng/mL vs. end-of-observation: 36 ng/mL). The current study revealed that plasma-based resuscitation normalized circulating heparan sulfate but not syndecan-1. Co-administration of CFC had no further effect on glycocalyx shedding suggesting a lack of its therapeutic potential. VExperimental in vivo study.

Trombosis venosa subclavia asociada a electrodo de marcapasos y síndrome de la plaqueta pegajosa

Sticky platelet syndrome is a qualitative platelet disorder in which low concentrations of adrenaline and adenosine diphosphate produce considerable platelet hyperaggregability. There has been much speculation on the origin of this disorder as its pathophysiological mechanisms of action are not yet clear. From a clinical point of view, it is associated with recurrent arterial and venous thrombosis in young patients, miscarriages, other obstetric complications and recurrent headaches.Its familial presentation has been described in the literature, suspecting that it is of a dominant autosomal hereditary nature. An acquired phenotype of the disease has also been reported in some particular patients, such as patients with chronic kidney disease on renal replacement therapy or after a kidney transplant, as well as in patients with inflammatory processes or immunosuppression. The case is presented of a patient with a history of difficult to manage headaches, a hypertensive syndrome associated with the pregnancy, and a foetal death. She also had sick sinus node syndrome and dysautonomia managed with a definitive dual-chamber pacemaker with a CLS sensor. There was then a thrombosis in the subclavian vein associated with the pacemaker electrode, being recurrent despite anticoagulation with warfarin and rivaroxaban, and even despite anti-aggregation treatment with acetyl salicylic acid. She was subsequently diagnosed with sticky platelet syndrome.

Possibilities of thermographic rating the level of microcirculation with local anesthesia in dentistry

In the pilot study, 22 healthy volunteers aged between 29-35 years of both sexes participated. To assess the degree of external vasoconstriction, a buccal region was chosen near the maxilla. Infiltration anesthesia was used with a 4% solution of articaine with epinephrine 1: 100 000 and 1: 200 000 at a dosage of 0.5-0.7 ml. The temperature distribution in the study area was estimated using a thermal imager Nec InfReC Thermo Gear G30. The study showed that the use of epinephrine in local anesthetics naturally has a moderate effect on hemodynamics in areas adjacent to the anesthesia depot. When using a low concentration of epinephrine (1:200 000), the projection hyperthermia of the skin is determined. Perhaps this is due to the activation of microcirculation due to an increase in capillary blood flow in the region above the zone of action of the epinephrine. From the point of view of physiological arterial hyperemia, this mechanism carries positive properties, since leads to an increase in tissue oxygenation. When using a high concentration of epinephrine (1:100 000), the zone of hypothermia of the skin is determined, which corresponds to the phenomenon of angiospastic ischemia.

Difference of catecholamine responses to exercise in men with trisomy 21, with or without chronotropic incompetence

ObjectiveOur purpose was to analyse if catecholamine responses to exercise would be different in Down syndrome (DS) with or without chronotropic incompetence. Research design and methodsTwenty five men with DS (mean age 22.2±3.2) and twenty six controls (CONT, mean age 22.5±1.4) participated in the study, and are divided into 3 groups: CONT, DS with chronotropic incompetence (DS+) and DS without chronotropic incompetence (DS−). During two treadmill incremental tests, blood samples were collected for the determination of hormonal and metabolic variables. ResultsTen out of 25 DS had chronotropic incompetence whereas no CONT. At rest, compared to CONT, despite similar physical activity, DS with chronotropic incompetence had significantly higher subcutaneous fat mass (p<0.001), lower epinephrine concentration (p<0.01), and higher leptin (p<0.01) and insulin concentrations (p<0.05). At peak exercise, all DS had lower heart rate, oxygen uptake and blood lactate concentrations than controls (p<0.001). During a ‘Submaximal incremental test’, DS with chronotropic incompetence had lower HR and lactate values (p<0.001) compared to CONT and DS without chronotropic incompetence (p<0.01). They also had blunted epinephrine and impaired norepinephrine responses to exercise compared to DS without chronotropic incompetence and CONT (p<0.01 and p<0.05 respectively). ConclusionsOur results indicate that catecholamine adaptations to exercise are not adequate in DS+ and are associated with exercise intolerance. Thus, this endocrine profile at rest and during exercise may limit endurance performance of DS.

Adipocyte dysfunction in rats with streptozotocin-nicotinamide-induced diabetes.

Administration of streptozotocin (STZ) and nicotinamide (NA) to adult rats allows for the induction of mild diabetes. However, this experimental model has not been fully characterized. This study was undertaken to determine the metabolic and secretory activity of adipose tissue in rats with STZ-NA-induced diabetes. Experiments were performed using epididymal adipocytes isolated from control and mildly diabetic rats. Lipogenesis, glucose transport as well as glucose and alanine oxidation, lipolysis, anti-lipolysis, cAMP levels and adipokine secretion were compared in cells isolated from the control and diabetic rats. Lipogenesis, glucose transport and oxidation were diminished in the adipocytes of diabetic rats compared with the fat cells of control animals. However, alanine oxidation appeared to be similar in the cells of non-diabetic and diabetic animals. Lipolytic response to low epinephrine concentrations was slightly increased in the adipocytes of diabetic rats; however, at higher concentrations of the hormone, lipolysis was similar in both groups of cells. The epinephrine-induced rise in cAMP levels was higher in the adipocytes of STZ-NA-induced diabetic rats, even in the presence of insulin. Lipolysis stimulated by dibutyryl-cAMP did not significantly differ, whereas anti-lipolytic effects of insulin were mildly decreased in the cells of diabetic rats. Secretion of adiponectin and leptin was substantially diminished in the adipocytes of diabetic rats compared with the cells of control animals. Our studies demonstrated that the balance between lipogenesis and lipolysis in the adipose tissue of rats with mild diabetes induced by STZ and NA is slightly shifted towards reduced lipid accumulation. Simultaneously, adiponectin and leptin secretion is significantly impaired.

Stress‐induced increase in muscle force: truth or myth?

Stress‐induced increase in muscle force: truth or myth?

Antioxidant and platelet aggregation inhibitor activities of black tea (Camellia sinensisL.) extract and fractions

The dried leaves of Camellia sinensis L., is a popular beverage consumed worldwide and contains bioactive compounds. The research was carried out to evaluate antioxidant and antiaggregation activities of black tea extract and fractions namely hexane, ethyl acetate, butanol and water fraction. Antioxidant activity of extract and four fractions of black tea were evaluated by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging method and total phenolic compound were determined. Platelet aggregation was determined using whole blood of hyperaggregation individual and analyzed by aggregometer after induction by epinephrine (EPN). The results showed that black tea extract, exhibited highest DPPH free radical scavenging acitivity with IC50 = 5.405 μg/mL among black tea fractions, but still lower comparing to (−)-epigallocatechin-3-gallate (EGCG) with IC50 = 0.505 μg/mL. The highest total phenolic compounds was ethyl acetate fraction (499.07 EGCG μg/mg) and the lowest was water fraction (149.77 EGCG μg/mg). Extract and fractions of black tea were capable in lowering platelet aggregation both at high and low concentrations of EPN (300 and 75 μM) inducer compared to untreated blood. Ethyl acetate, water fractions and extract of black tea showed similar platelet antiaggregation compared with aspirin as positive control.

Reply to letter “Pyruvate metabolism in working human skeletal muscle” by Henderson et al.

The following is the abstract of the article discussed in the subsequent letter: The aim of this study was to determine whether the decreased muscle and blood lactate during exercise with hyperoxia (60% inspired O2) vs. room air is due to decreased muscle glycogenolysis, leading to decreased

Letter to the Editor

Letter to the Editor

Hyperoxia decreases muscle glycogenolysis, lactate production, and lactate efflux during steady-state exercise

The aim of this study was to determine whether the decreased muscle and blood lactate during exercise with hyperoxia (60% inspired O2) vs. room air is due to decreased muscle glycogenolysis, leading to decreased pyruvate and lactate production and efflux. We measured pyruvate oxidation via PDH, muscle pyruvate and lactate accumulation, and lactate and pyruvate efflux to estimate total pyruvate and lactate production during exercise. We hypothesized that 60% O2 would decrease muscle glycogenolysis, resulting in decreased pyruvate and lactate contents, leading to decreased muscle pyruvate and lactate release with no change in PDH activity. Seven active male subjects cycled for 40 min at 70% VO2 peak on two occasions when breathing 21 or 60% O2. Arterial and femoral venous blood samples and blood flow measurements were obtained throughout exercise, and muscle biopsies were taken at rest and after 10, 20, and 40 min of exercise. Hyperoxia had no effect on leg O2 delivery, O2 uptake, or RQ during exercise. Muscle glycogenolysis was reduced by 16% with hyperoxia (267 +/- 19 vs. 317 +/- 21 mmol/kg dry wt), translating into a significant, 15% reduction in total pyruvate production over the 40-min exercise period. Decreased pyruvate production during hyperoxia had no effect on PDH activity (pyruvate oxidation) but significantly decreased lactate accumulation (60%: 22.6 +/- 6.4 vs. 21%: 31.3 +/- 8.7 mmol/kg dry wt), lactate efflux, and total lactate production over 40 min of cycling. Decreased glycogenolysis in hyperoxia was related to an approximately 44% lower epinephrine concentration and an attenuated accumulation of potent phosphorylase activators ADPf and AMPf during exercise. Greater phosphorylation potential during hyperoxia was related to a significantly diminished rate of PCr utilization. The tighter metabolic match between pyruvate production and oxidation resulted in a decrease in total lactate production and efflux over 40 min of exercise during hyperoxia.

Method development for the enantiomeric purity determination of low concentrations of adrenaline in local anaesthetic solutions by capillary electrophoresis

l-Adrenaline is often included in local anaesthetic (LA) solutions for injection to improve the quality of the anaesthetic block. The concentration of the LA is between 2.5 and 20 mg/ml and the concentration of adrenaline is typically ≤0.1% of the LA concentration. In order to follow the racemization into d-adrenaline, not only is chiral separation needed but also sufficient resolution from the LA and other components of the injection solution. Furthermore, very high sensitivity is needed in order to be able to determine the d-enantiomer at very low concentrations, i.e. down to about 0.1 μg/ml. The development of a chiral capillary electrophoresis method that is able to determine the racemization of adrenaline is described, together with a limited validation. Samples are injected without pretreatment and analysed with a capillary electrophoresis buffer containing 40 mM heptakis(2,6-di- O-methyl)-β-cyclodextrin, 0.10 M phosphoric acid and 0.05 M triethanolamine. The amounts of d-adrenaline found in the LA products tested were typically <3% of the l-adrenaline concentration and <0.003% of the LA concentration.

Epinephrine activates both Gs and Gi pathways, but norepinephrine activates only the Gs pathway through human beta2-adrenoceptors overexpressed in mouse heart.

Isoproterenol increases and decreases contractile force at low and high concentrations, respectively, through beta(2)-adrenoceptors overexpressed in transgenic mouse heart (TG4), consistent with activation of both G(s) and G(i) proteins. Using TG4 hearts, we demonstrated that epinephrine behaves like isoproterenol, but norepinephrine does not. Epinephrine both increased (-log EC(50)M = 9.4) and decreased (-log EC(50)M = 6.5) left atrial force. Pertussis toxin (PTX) abolished the negative inotropic effects of epinephrine, consistent with mediation through G(i) protein. Norepinephrine only increased contractile force (-log EC(50)M = 7.5). Norepinephrine (10-100 microM) prevented the positive inotropic effects but hardly affected the negative inotropic effects of epinephrine. Cardiodepressive epinephrine concentrations (1-10 microM) antagonized the positive inotropic effects of norepinephrine. In the free wall of TG4 right ventricle, norepinephrine and low epinephrine concentrations caused positive inotropic effects, and high epinephrine concentrations caused PTX-sensitive negative inotropic effects, as observed in the left atrium. Epinephrine (10 nM), a concentration causing maximum increase in contractile force, and norepinephrine (1 and 100 microM) increased cAMP-dependent protein kinase activity in TG4 left ventricle. Cardiodepressive concentrations of epinephrine (1 and 100 microM) did not increase cAMP-dependent protein kinase activity. The inotropic results were simulated with a model of two beta(2)-adrenoceptor sites. For one site involved in receptor coupling to G(s), both epinephrine and norepinephrine compete. The other site, recognized by epinephrine but not by norepinephrine, leads to receptor G(i) coupling.

Shear-induced von Willebrand factor-mediated platelet surface translocation of the CD40 ligand

Background: Platelets, which can adhere to damaged vascular surfaces and release bioactive substances upon activation, may play important roles in regulating local inflammatory responses. We focused on the surface translocation of CD40 ligand (CD40L) molecules when the platelets are exposed to a high shear stress. Method: Blood specimens were obtained from eight apparently healthy adult donors. The number of CD40L molecules appearing on the surface of platelets after exposure of platelet-rich plasma to a shear rate of 10,800 s −1 was determined by quantitative flow cytometry. Results: The number of anti-CD40L IgG molecules bound per platelet increased from 15±80/platelet before to 355±122/platelet after exposure of the platelets to a shear rate of 10,800 s −1 ( p<0.01), but not after their exposure to the relatively low shear rate of 1200 s −1. This shear-induced platelet surface translocation of CD40L, mediated by the von Willebrand factor (VWF)–GP Ibα interaction, was enhanced in the presence of a low concentration of epinephrine (100 nM), which by itself, however, could not cause platelet activation. Our results demonstrate that fluid force induces the appearance of CD40L on the surface of platelets, and also that this phenomenon is enhanced in the presence of a low concentration of epinephrine, corresponding to that released by sympathetic stimulation.

Qualitatively different response of isolated rabbit aorta to methylene blue administered from intimal and adventitial surface.

An isolated rabbit aortic preparation, on which administered drugs act selectively from intimal or adventitial surface, was made. Epinephrine (0.1 nM approximately 10 microM) produced concentration-dependent increase of intraluminal pressure, which is due to increase of contraction of the vascular smooth muscle. Sensitivity of contractile response to epinephrine administered from intimal surface was significantly higher than that administered from adventitial surface. The contractile response to epinephrine administered from intimal surface was reduced by removal of the endothelium. Cocaine (100 microM) potentiated the contractile response to epinephrine administered from adventitial surface. Cocaine also potentiated the contractile response to high concentration of epinephrine administered from intimal surface, while the drug reduced the contractile response to low concentration of epinephrine. Methylene blue (100 microM) administered from adventitial surface produced a marked contraction, while methylene blue administered from intimal surface produced a marked relaxation. The relaxing response to methylene blue administered from intimal surface was reduced by the removal of endothelium. Prazosin (1 microM) suppressed the contractile response to methylene blue administered from adventitial surface, indicating that methylene blue released norepinephrine from adrenergic nerve terminals. The contractile response to epinephrine administered from intimal surface was reduced by methylene blue administered from intimal surface. The present study clearly demonstrated variation in mechanical response of isolated rabbit aortic preparation with intimal or adventitial surface of drug entry.

Low catecholamine concentrations protect adult rat ventricular myocytes against apoptosis through cAMP-dependent extracellular signal-regulated kinase activation.

Catecholamines have complex effects on cardiac myocyte growth and survival, including the triggering of apoptosis at high concentration. Here, we examined whether at a lower concentration, catecholamine protected adult rat ventricular myocytes from apoptosis in vitro. Myocytes were exposed to staurosporine (ST, 10 microM) for 18 h, with or without epinephrine (0.1 or 10 microM) or fetal calf serum (10%). Apoptosis was assessed after 48 h of culture in terms of DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling method, DNA gel electrophoresis). Epinephrine (0.1 microM) and serum reduced ST-induced myocyte apoptosis by approximately 50% (n = 12 cultures, P <.001), whereas epinephrine and serum alone did not influence the low apoptotic rate in control cultures. In contrast, 10 microM epinephrine induced marked apoptosis in ST-free conditions. The protective effects of 0.1 microM epinephrine and serum were blunted by the tyrosine kinase inhibitor genistein (n = 12 cultures, P <. 001). Extracellular signal-regulated kinase (ERK) activity was stimulated by 0.1 microM epinephrine but not by 10 microM epinephrine. Furthermore, the protective effect of epinephrine was mimicked by isoproterenol (1 microM) and forskolin (1 microM) but not by phenylephrine (10 microM) and was blunted by propranolol (10 microM) but not by prazozin (10 microM). Finally, isoproterenol and forskolin activated ERK, an effect that was blunted by propranolol. In conclusion, low epinephrine concentrations attenuate ST-induced apoptosis of adult cardiac myocytes in vitro, an effect mediated by coupling between the cAMP pathway and ERK activation. This suggests that a minimal adrenergic tone is essential for myocyte survival in conditions of unusual stress.

Cardiovascular responses in patients and dentists during dental treatment

Changes in mean heart rate and in mean systolic and diastolic blood pressure are induced by both the patient's anticipation of scheduled treatment and the actual dental treatment. Most of these changes are within the normal physiological variations, but significant changes are observed before administration of a local anaesthetic, during subgingival debridement and during extractions. Individual changes in heart rate and blood pressure are affected by age, gender, hypertension and previous dental experience. Pain also plays an important role in the cardiovascular response during dental treatment, which stresses the need for adequate analgesia. For this purpose, local anaesthetics with low concentrations of epinephrine seem preferable. They induce less pronounced cardiovascular responses than local anaesthetics with higher concentrations of epinephrine or without epinephrine. The changes in heart rate and blood pressure that occur in the dentist during the treatment are also discussed.