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Biomedical subjects

Danielle Jacques

Publications and source records attributed to Danielle Jacques.

At least 19 recordsLinked to original sources
PubMed2007

NPY regulates human endocardial endothelial cell function.

Growing evidence suggests that endocardial endothelial cells (EECs) may play an important role in the regulation of cardiac function by releasing several cardioactive factors such as endothelin-1 (ET-1), Angiotensin II (Ang II) and nitric oxide (NO). In our laboratory, we demonstrated that similar to ET-1, EECs do possess different types of NPY receptors, specifically Y(1) and Y(2) receptors. Furthermore, activation of these receptors was found to increase the steady-state level of intracellular free Ca(2+) in EECs and the frequency of beating of cardiomyocytes. In addition, NPY was also found to be present in EECs, and an increase of steady-state intracellular free Ca(2+) induced the release of this peptide from these cells. Thus, similar to ET-1, NPY seems to be released from EECs and this peptide seems to regulate excitation-secretion of these cells as well as excitation-contraction coupling of ventricular cardiomyocytes.

Animals↗
PubMed2006

ETB receptor dependent alteration in aortic responses to ET-1 in the cardiomyopathic hamster.

The aim of this study was to verify whether an alteration in the aortic endothelin-1 (ET-1) response takes place in UM-X7.1 cardiomyopathic hamsters. Our results showed that ET-1 (10(-12) - 10(-5) mol/L) induces dose-dependent sustained increases in tension in the intact and endothelium denuded aortas from both normal and cardiomyopathic hamsters. The EC50 values of ET-1 of both intact and endothelium denuded aortas of normal hamsters were similar (2.2 x 10(-9) mol/L and 1.8 x 10(-9) mol/L, respectively). However, in cardiomyopathic hamsters, the EC50 of ET-1 in intact aortas was higher (1.5 x 10(-8) mol/L) than that of the endothelium denuded preparations (2.7 x 10(-9) mol/L). The EC50 of ET-1 in normal and cardiomyopathic hamster denuded aortas were similar. However, the EC50 of ET-1 in intact aortas of cardiomyopathic hamster was higher (1.5 x 10(-8) mol/L) than that of normal hamsters (2.2 x 10(-9) mol/L). Pre-treatment with the ETA receptor antagonist ABT-627 (10(-5)mol/L) of intact and endothelium denuded aortas from both normal and cardiomyopathic hamsters significantly prevented ET-1 (10(-7) mol/L) from inducing an increase in tension. Pre-treatment with the ETB receptor antagonist A-192621 (10(-5) mol/L) had no effect on the ET-1-induced increase in tension in endothelium denuded aortas of both normal and cardiomyopathic hamsters, as well as in intact preparations of normal animals. However, blockade of the ETB receptors in intact aortas of cardiomyopathic hamsters significantly (p < 0.001) potentiated the ET-1-induced increase in tension. In summary, an attenuation of the contraction response to ET-1 was found in UM-X7.1 cardiomyopathic hamsters when compared with normal age-matched hamsters. This alteration of the ET-1 effect in the aortas of cardiomyopathic hamsters seems to be dependent on the presence of the endothelium and could be due, in part, to an increase in the contribution of endothelial ETB receptors to relaxation, which in turn acts as a physiological depressor of ET-1 vasoconstriction. Our results suggest that an increase in the endothelium ETB receptor density may play a role in the development of hypotension in UM-X7.1 cardiomyopathic hamsters.

Animals↗
PubMed2006

Roles of nuclear NPY and NPY receptors in the regulation of the endocardial endothelium and heart function.

It is now well accepted that the heart is a multifunctional organ in which endothelial cells, and more particularly endocardial endothelial cells (EECs), seem to play an important role in regulating and maintaining cardiac excitation-contraction coupling. Even if major differences exist between vascular endothelial cells (VECs) and EECs, all endothelial cells including EECs release a variety of auto- and paracrine factors such as nitric oxide, endothelin-1, angiotensin II, and neuropeptide Y. All these factors were reported to affect cardiomyocyte contractile performance and rhythmicity. In this review, findings on the morphology of EECs, differences between EECs and other types of endothelial cells, interactions between EECs and the adjacent cardiomyocytes, and effects of NPY on the heart will be presented. We will also show evidence on the presence and localization of NPY and the Y1 receptor in the endocardial endothelium and discuss their role in the regulation of cytosolic and nuclear free calcium.

Animals↗
PubMed2005

Angiotensin II-induced increase of T-type Ca2+ current and decrease of L-type Ca2+ current in heart cells.

The effect of angiotensin II (Ang II) on the T- and L-type calcium currents (I(Ca)) in single ventricular heart cells of 18-week-old fetal human and 10-day-old chick embryos was studied using the whole-cell voltage clamp technique. Our results showed that in both, human and chick cardiomyocytes, Ang II (10(-7)M) increased the T-type calcium current and decreased the L-type I(Ca). The effect of Ang II on both types of currents was blocked by the AT1 peptidic antagonist, [Sar1, Ala8] Ang II (2 x 10(-7)M). Protein kinase C activator, phorbol 12,13-dibutyrate, mimicked the effect of Ang II on the T- and L-type calcium currents. These results demonstrate that in fetal human and chick embryo cardiomyocytes Ang II affects the T- and L-type Ca2+ currents differently, and this effect seems to be mediated by the PKC pathway.

Angiotensin II↗
PubMed2005

The distribution and density of ET-1 and its receptors are different in human right and left ventricular endocardial endothelial cells.

Evidence suggests that endocardial endothelial cells (EECs) may play a role in the regulation of cardiac function by releasing ET-1. Furthermore, reports in the literature suggested that differences may exist in peptide receptor distribution between the left and right EECs. In this study, we verified if the distribution and density of ET-1 and its receptors could be different in right as compared to left ventricular EECs, and whether this difference may affect ET-1-induced increase of intracellular calcium. Using immunofluorescence and 3D confocal microscopy, our results showed that in both cell types, the ET(A) receptor is present and is homogeneously distributed throughout the two cell types. The relative density of the ET(A) receptor is similar in both right and left ventricular EECs. The ET(B) receptor is also present in right and left ventricular EECs, however, the relative density of the ET(B) receptor is higher in the nucleus as compared to the cytosol. In addition, the ET(B) receptor density was found to be higher in left EECs as compared to right EECs. In addition, our results showed that ET-1 is present in the cytosol and the nucleus of both types of cells and that the relative density of ET-1 is higher in right as compared to left ventricular EECs. Moreover, using the Fura-2 calcium measurement technique, our results showed that in left ventricular EECs, both ET(A) and ET(B) receptor activation mediated the effect of ET-1 on intracellular calcium, whereas in right ventricular EECs, this effect was solely mediated by the ET(A) receptor. In conclusion, our results showed that ET-1 and its receptors are present in both right and left ventricular EECs. However, the distribution and relative density of ET-1 and its receptors seem to be different in right EECs as compared to left EECs.

Calcium↗
PubMed2005

Angiotensin II induced increase in frequency of cytosolic and nuclear calcium waves of heart cells via activation of AT1 and AT2 receptors.

The aim of this work is to verify if Angiotensin II (Ang II) affects the frequency of spontaneous cytosolic and nuclear Ca2+ waves in chick embryonic cardiomyocytes and if this effect is mediated via the activation of AT1 and/or AT2 receptors. Using the rapid scan technique of confocal microscopy, we observed that Ang II (10(-8)M) increases the frequency of cytosolic and nuclear Ca2+ waves. This effect was accompanied by a decrease in the amplitude of nuclear Ca2+ waves and an absence of effect on the amplitude of cytosolic Ca2+ waves. The effect of the octapeptide on both frequency and amplitude of the nuclear waves was prevented by the AT1 receptor antagonist L158809. However, blockade of the AT2 receptor using the antagonist PD123319 (10(-7)M) only prevented the effect of Ang II on the frequency of Ca2+ waves. Furthermore, the effect was prevented by both a PKC inhibitor (bisindolylmaleimide) and a PKC activator (phorbol 12,13-dibutyrate). In addition, the Ang II effect was not prevented by the blocker of the pacemaker current If. These results demonstrate that Ang II, via the activation of its receptors AT1 and AT2, affects the frequency of spontaneous Ca2+ waves and this effect seems to be mediated by the PKC pathway.

Angiotensin II↗
PubMed2005

NHE-1-dependent intracellular sodium overload in hypertrophic hereditary cardiomyopathy: prevention by NHE-1 inhibitor.

The purpose of this study was to verify whether myocardial intracellular Na(+) overload may take place in the hereditary cardiomyopathic hamster (CMH), as a result of an increased activity of the Na(+)-H(+) exchanger isoform-1 (NHE-1). Our results showed that simultaneous intracellular Na(+) and Ca(2+) overloads as well as an increase of NHE-1 protein level took place during the development of necrosis and hypertrophy in the CMH. Treatment of 30-day-old CMHs during the development of necrosis and in the absence of hypertrophy with the specific NHE-1 inhibitor EMD87580 (EMD) for 50 days significantly prevented the increase of NHE-1 protein level and intracellular Na(+) and Ca(2+) overloads as well as necrosis. Treatment of CMHs during the development of hypertrophy with EMD for 198 days prevented the development of both necrosis and hypertrophy. In conclusion, our results suggest that NHE-1 overexpression as well as Na(+) and Ca(2+) overloads do take place during the development of necrosis and hypertrophy in hereditary CMHs. Moreover, our results suggest that the blockade of NHE-1 by EMD87580 prevents these diseases by preventing the increase of Na(+) influx through the NHE-1.

Animals↗
PubMed2003

Presence of neuropeptide Y and the Y1 receptor in the plasma membrane and nuclear envelope of human endocardial endothelial cells: modulation of intracellular calcium.

The aims of the present study were to investigate the presence and distribution of NPY and the Y1 receptor in endocardial endothelial cells (EECs), to verify if EECs can release NPY, and to determine if the effect of NPY on intracellular calcium is mediated via the Y1 receptor. Immunofluorescence, 3-D confocal microscopy and radioimmunoassay techniques were used on 20-week-old human fetal EECs. Our results showed that NPY and the Y1 receptor are present in human EECs (hEECs) and that their distributions are similar, the fluorescence labelling being higher in the nucleus and more particularly at the level of the nuclear envelope when compared with the cytosol. Using radioimmunoassay, we demonstrated that EECs are a source of NPY and can secrete this peptide upon a sustained increase of intracellular calcium ([Ca]i). Using fluo-3 and 3-D confocal microscopy technique, superfusion of hEECs as well as EECs isolated from rat adult hearts with increasing concentrations of NPY induced a dose-dependent, sustained increase in free cytosolic and nuclear Ca2+ levels. This effect of NPY on EEC [Ca]i was completely reversible upon washout of NPY and was partially blocked by BIBP3226, a selective Y1 receptor antagonist. The results suggest that NPY and Y1 receptors are present in the EECs of 20-week-old human fetal heart and they share the same distribution and localization inside the cell. In addition, EECs are able to secrete NPY in response to an increase in [Ca]i, and the Y1 receptor as well as other NPY receptors seem to participate in mediating the effects of NPY on [Ca]i in these cells. Thus, NPY released by EECs may modulate excitation-secretion coupling of these cells.

Aniline Compounds↗
PubMed2003

Activation of sarcolemma and nuclear membranes ET-1 receptors regulates transcellular calcium levels in heart and vascular smooth muscle cells.

The use of an ET-1 fluorescent probe in human heart and vascular smooth muscle cells showed that ET-1 receptors are present at both the sarcolemma and nuclear envelope membranes. The use of immunofluorescence studies showed that the ETA receptor was mainly present at the sarcolemma and cytosolic levels. However, the ETB receptor was present at the sarcolemma and the cytosol, as well as the nuclear envelope membranes and the nucleoplasm. In addition, ET-1 immunoreactivity was seen in the cytosol and the nucleus. Using Ca2+ fluorescent probes such as Fluo-3, Indo 1, and yellow cameleon, as well as confocal microscopy three-dimensional image measurement technique, stimulation of ET-1 receptors at the sarcolemma membranes induced an increase of cytosolic and nuclear free Ca2+ levels. This effect of extracellular ET-1 was blocked by removal of extracellular calcium. Direct stimulation of ET-1 receptors at the nuclear envelope membranes also induced an increase of intranuclear free Ca2+ level. Our results suggest that the stimulation of sarcolemmal Ca2+ influx by ET-1 seems to be due to the activation of ETA and ETB receptors. However, the increase of nucleoplasmic Ca2+ levels by cytosolic ET-1 seems to be mediated via the activation of ETB receptors. Activation of nuclear membranes ETB receptors seems to prevent nuclear Ca2+ overload and may protect the cell from apoptosis.

Calcium↗
PubMed2003

Isradipine prevents the development of spontaneously occurring cardiac necrosis in cardiomyopathic hamster.

Recent studies on the heart necrotizing process at the early stages of hamster polymyopathy have led us to believe that this hereditary disease derives from an anomalous transmembrane ion flux due to the presence of slow Na+ channels that contribute to intracellular Na+ accumulation which promote intracellular Ca2+ overload via the Ca2+ influx through the Na+-Ca2+ exchanger. In the present study, we investigated the potential beneficial effect of chronic treatment with a dual L-type Ca2+ and slow Na+ channel blockers isradipine, on the development of necrosis in myopathic hamster hearts. Young cardiomyopathic (CM) hamsters (CMH) were treated with isradipine (0.1 mg x kg(-1) x day(-1)) and nifedipine (1 mg x kg(-1) x day(-1)) for 4 consecutive weeks. Microscopic assessments were carried out in staged serial paraffin sections of heart ventricles from tissues freshly dissected at autopsy. In comparison with control nontreated hearts, which exhibited numerous necrotic calcific foci, myolytic lesions, and dilated right ventricle, isradipine treatment prevented, in a significant manner, all the above spontaneous pathological changes, while nifedipine had no effect. Our present observations provide evidence for the first time that in vivo treatment with a DHP Ca2+ channel blocker, isradipine, is cardioprotective against the development of necrosis in hereditary cardiomyopathy in the hamster. It is possible that the protective effect of isradipine in CMH could be largely due to the indirect blockade of Ca2+ influx through the Na+-Ca2+ exchanger as well as to possible direct blockade of Ca2+ influx through the T-type Ca2+ channel.

Animals↗
PubMed2003

Modulation of intracellular Ca2+ via L-type calcium channels in heart cells by the autoantibody directed against the second extracellular loop of the alpha1-adrenoceptors.

The effects of methoxamine, a selective alpha1-adrenergic receptor agonist, and the autoantibody directed against the second extracellular loop of alpha1-adrenoceptors were studied on intracellular free Ca2+ levels using confocal microscopy and ionic currents using the whole-cell patch clamp technique in single cells of 10-day-old embryonic chick and 20-week-old fetal human hearts. We observed that like methoxamine, the autoantibody directed against the second extracellular loop of alpha1-adrenoreceptors significantly increased the L-type calcium current (I(Ca(L))) but had no effect on the T-type calcium current (I(Ca(T))), the delayed outward potassium current, or the fast sodium current. This effect of the autoantibody was prevented by a prestimulation of the receptors with methoxamine and vice versa. Moreover, treating the cells with prazosin, a selective alpha1-adrenergic receptor antagonist blocked the methoxamine and the autoantibody-induced increase in I(Ca(L)), respectively. In absence of prazosin, both methoxamine and the autoantibody showed a substantial enhancement in the frequency of cell contraction and that of the concomitant cytosolic and nuclear free Ca2+ variations. The subsequent addition of nifedipine, a specific L-type Ca2+ channel blocker, reversed not only the methoxamine or the autoantibody-induced effect but also completely abolished cell contraction. These results demonstrated that functional alpha1-adrenoceptors exist in both 10-day-old embryonic chick and 20-week-old human fetal hearts and that the autoantibody directed against the second extracellular loop of this type of receptors plays an important role in stimulating their activity via activation of L-type calcium channels. This loop seems to have a functional significance by being the target of alpha1-receptor agonists like methoxamine.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2003

Bradykinin induced a positive chronotropic effect via stimulation of T- and L-type calcium currents in heart cells.

Using Fluo-3 calcium dye confocal microscopy and spontaneously contracting embryonic chick heart cells, bradykinin (10(-10) M) was found to induce positive chronotropic effects by increasing the frequency of the transient increase of cytosolic and nuclear free Ca2+. Pretreatment of the cells with either B1 or B2 receptor antagonists (R126 and R817, respectively) completely prevented bradykinin (BK) induced positive chronotropic effects on spontaneously contracting single heart cells. Using the whole-cell voltage clamp technique and ionic substitution to separate the different ionic current species, our results showed that BK (10(-6) M) had no effect on fast Na+ inward current and delayed outward potassium current. However, both L- and T-type Ca2+ currents were found to be increased by BK in a dose-dependent manner (10(-10)-10(-7) M). The effects of BK on T- and L-type Ca2+ currents were partially blocked by the B1 receptor antagonist [Leu8]des-Arg9-BK (R592) (10(-7) M) and completely reversed by the B2 receptor antagonist D-Arg[Hyp3,D-Phe7,Leu8]BK (R-588) (10(-7) M) or pretreatment with pertussis toxin (PTX). These results demonstrate that BK induced a positive chronotropic effect via stimulation of T- and L-type Ca2+ currents in heart cells mainly via stimulation of B2 receptor coupled to PTX-sensitive G-proteins. The increase of both types of Ca2+ current by BK in heart cells may explain the positive inotropic and chronotropic effects of this hormone.

Aniline Compounds↗
PubMed2003

Angiotensin II and its receptors in human endocardial endothelial cells: role in modulating intracellular calcium.

The aims of the present study are to investigate the presence and distribution of angiotensin II (Ang II), as well as AT1 and AT2 receptors, in endocardial endothelial cells (EECs) and to determine if the effect of Ang II on intracellular calcium in these cells is mediated via the AT1 or the AT2 receptor. Immunofluorescence and 3D confocal microscopy techniques were used on 20-week-old fetal human EECs. Our results showed that Ang II and its receptors, the AT1 and the AT2 types, are present and exhibit a different distribution in human EECs. Ang II labelling is found throughout the cell with a fluorescence signal higher in the cytosol when compared with the nucleus. Like Ang II, the AT1 receptor fluorescence signal is also homogeneously distributed in human EECs but with a preferential labelling at the level of the nucleus, while the AT2 receptor labelling is solely present in the nucleus. Using fluo-3 and 3D confocal microscopy technique, superfusion of human EECs with increasing concentration of Ang II induced a dose-dependent sustained increase in free cytosolic and nuclear Ca2+ levels. This effect of Ang II on human EEC's intracellular Ca2+ ([Ca2+]) was completely prevented by losartan, an AT1 receptor antagonist. Our results suggest that Ang II, as well as AT1 and AT2 receptors, is present but differentially distributed in EECs of 20-week-old fetal human hearts, and that the AT1 receptor mediates the effects of Ang II on [Ca2+]i in these cells.

Angiotensin II↗
PubMed2002

Role of endothelin-1 receptors in the sarcolemma membrane and the nuclear membrane in the modulation of basal cytosolic and nuclear calcium levels in heart cells.

Our previous work in heart cells showed that the nuclear envelope membranes possess receptors, such as those for angiotensin II. Using non-working single cells from the hearts of 10-day chick embryos and the confocal microscopy technique, our present results show that stimulation of endothelin-1 (ET-1) receptors at the sarcolemma membrane induced a dose-dependent sustained increase in basal cytosolic and nuclear calcium levels that was insensitive to the ET(A) and ET(B) receptor antagonists BQ123 and BQ788. The cytosolic application of ET-1 induced a dose-dependent increase in the sustained basal nuclear Ca(2+) concentration that was insensitive to BQ123 and BQ788. The ET-1 receptors at the nuclear envelope membrane were more sensitive to ET-1 than those located at the sarcolemma membrane of heart cells. Cytosolic application of ET-1 prevented sustained basal cytosolic Ca(2+) uptake by the nuclei. The use of an ET-1 fluorescent probe demonstrated the presence of ET-1 receptors at both the sarcolemma membrane and the nuclear envelope membrane. Thus our results suggest that ET-1 receptors that are insensitive to BQ123 and BQ788 are present at both the sarcolemma and nuclear envelope membranes. Extracellular and cytosolic ET-1 may play a role in regulating basal cytosolic and nuclear Ca(2+) levels in heart cells.

Animals↗
PubMedDate not supplied

Effect of diabetes mellitus and insulin on the regulation of the PepT 1 symporter in rat jejunum.

This investigation focused on studying the effects of insulin-dependent diabetes mellitus and insulin treatment on absorption of glycylsarcosine (Gly-Sar) across the Sprague-Dawley rat jejunum, using in situ perfusion in a physiologic acidic microenvironment at pH 6.0. Rats were divided into five groups: normal controls in group I, normal colchicine-treated rats in group II, normal cytochalasin-treated rats in group III, streptozotocin-induced diabetic rats in group IV, and insulin-treated diabetic rats in group V. Histologic studies of the five different groups showed morphologic changes upon induction of diabetes and treatments with colchicine and cytochalasin and several variations in post-1 month diabetic rats treated with insulin. The rate of uptake of Gly-Sar was significantly reduced in the diabetic state. The comparison of colchicine-treated and cytochalasin-treated rats to the diabetic group suggests that an intact cytoskeleton and tight junctions may play a role in jejunal dipeptide absorption. In the diabetic and insulin-treated group, the dipeptide influx rate was significantly increased compared to that of the nontreated controls. The regulation of the PepT 1 symporter was further assessed by immunostaining and Western blot analyses in the normal, diabetic, and diabetic and insulin-treated groups. Our results showed that a downregulation of PepT 1 in the diabetics seemed to be due in part to the low systemic insulin levels, and not necessarily to hyperglycemia. In addition, the results suggest a probable role of systemic insulin binding at the vascular site of the jejunal epithelium, and the role that this hormone may be playing in the regulation and probably cellular trafficking of PepT1.

Animals↗
PubMedDate not supplied

Immunofluorescence revealed the presence of NHE-1 in the nuclear membranes of rat cardiomyocytes and isolated nuclei of human, rabbit, and rat aortic and liver tissues.

Using immunofluorescence and 3-dimensional confocal microscopy techniques, the present study was designed to verify if NHE-1 is present at the level of the nuclear membrane in cells that are known to express this type of exchanger. Nuclei were isolated from aortic tissues of adult human, rabbit, and rats, as well as from liver tissues of human fetus, and adult rabbit and rat. In addition, cultured ventricular cardiomyocytes were isolated from 2-week-old rat. Our results showed the presence of NHE-1 in isolated nuclei of aortic vascular smooth muscle and liver of human, rabbit, and rat. NHE-1 seems to be distributed throughout the isolated nucleus and more particularly at the level of the nuclear membranes. The relative fluorescence density of NHE-1 was significantly higher (p < 0.05) in isolated liver nuclei of human, when compared with those of rabbit and rat. However, in isolated nuclei of aortic vascular smooth muscle, the relative fluorescence density of NHE-1 was significantly (p < 0.001) higher in the rabbit when compared with human and rat. In cultured rat ventricular cardiomyocytes, NHE-1 fluorescent labeling could be easily seen throughout the cell, including the nucleus, and more particularly at both the sarcolemma and the nuclear membranes. In rat cardiomyocytes, the relative fluorescence density of NHE-1 of the sarcolemma membrane, including the cytosol, was significantly lower than that of the whole nucleus (including the nuclear envelope membranes). In conclusion, our results showed that NHE-1 is present at the nuclear membranes and in the nucleoplasm and its distribution and density may depend on cell type and species used. These results suggest that nuclear membranes' NHE-1 may play a role in the modulation of intranuclear pH.

Adult↗