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C Lugnier

Publications and source records attributed to C Lugnier.

71 records · Page 4Linked to original sources
PubMed1989

A comparison of cyclic AMP signaling system in rat aortic myocytes in primary culture and aorta.

Cyclic AMP (cAMP) metabolism has been studied in rat aortic myocytes grown in primary culture to characterize this second messenger system in vascular smooth muscle cells that retain responses to vasoactive drugs. For comparison, cAMP metabolism was also studied in the aorta from donor rats. Adenylate cyclase activity from myocytes and from the aorta was stimulated to a similar degree by GTP, NaF, or forskolin, and the enzyme activation produced by isoproterenol or vasoactive intestinal polypeptide was observed only in the presence of GTP. A cAMP phosphodiesterase activity was found in homogenates from cultured myocytes and aorta as well, and it was similarly stimulated by calmodulin in both cases. The rates of cAMP production and degradation were about seven-fold higher in cultured myocytes than in aorta. Basal levels of cAMP were also higher in the cultured cells than in the aorta. Hormones and drugs acting on adenylate cyclase or cAMP-phosphodiesterase in cell-free preparations altered the cAMP content of undisrupted cultured myocytes and aorta in the expected manner. Differences between cultured myocytes and aorta resided in the courses of drug-induced cAMP increases and in the magnitude of the cAMP response to isoproterenol, which was markedly increased in cultured myocytes compared with aorta. It is concluded that, despite some quantitative differences, the cAMP system of rat aortic myocytes grown in primary culture has characteristics similar to those displayed in rat isolated aorta. These cells are therefore suitable for studying the effects of drugs involving cAMP as a second messenger.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Comparison of cyclic nucleotide phosphodiesterase isoforms from rat heart and bovine aorta. Separation and inhibition by selective reference phosphodiesterase inhibitors.

The resolution as well as the biochemical properties of the multiple molecular forms of cyclic nucleotide phosphodiesterase, in a given tissue, may be strongly dependent upon experimental conditions of preparation (extraction of crude enzyme from tissues and fractionation procedures). In the present study, we compare the different molecular forms of cardiac (rat heart ventricle) and vascular (bovine aorta) phosphodiesterase isolated from crude extracts prepared either in sucrose medium or in hypotonic medium (in the presence of protease inhibitors and ion chelators) using two different fractionation procedures: isoelectric focusing on flat gel bed and DEAE-Trisacryl anion exchange chromatography. Both the calmodulin-dependent and the cAMP-specific forms exhibited close IEF and chromatographic patterns and showed similar sensitivities towards reference inhibitors regardless of the tissue of origin. In marked contrast, the cGMP-specific isoform notably differed from one to another tissue with respect to its biochemical properties (only the cardiac tissue being capable of stimulation by cGMP) and sensitivities to xenobiotics. Thus the possibility exists that pharmacological agents may modulate phosphodiesterase activity differently in cardiac and vascular target tissues.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1988

Interaction of calmodulin and calcium antagonists with [3H]diltiazem and [3H]nitrendipine binding sites.

The interaction of calmodulin antagonists and hydrophobic calcium antagonists with calmodulin and calcium antagonist ( [3H]nitrendipine and [3H]diltiazem) binding sites was investigated. The classical calmodulin antagonists calmidazolium, trifluorperazine, and W-7 were active at similar concentrations in the three experimental systems. The hydrophobic calcium antagonists prenylamine and bepridil, however, interacted with [3H]diltiazem binding at concentrations up to 50 times lower than their calmodulin inhibiting concentrations. The structural requirements for binding to calmodulin and to calcium channels are thus not identical for these hydrophobic drugs, suggesting that the calcium channel interacting properties of these antagonists are not a direct consequence of their calmodulin binding properties.

Animals↗
PubMed1987

Role of cyclic AMP- and cyclic GMP-phosphodiesterases in the control of cyclic nucleotide levels and smooth muscle tone in rat isolated aorta. A study with selective inhibitors.

Three isoforms of cyclic nucleotide phosphodiesterase (PDE) have been recently isolated from aortic tissue and two of them specifically hydrolyzed adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3':5'-cyclic monophosphate (cGMP), respectively (Lugnier et al., Biochem. Pharmac. 35, 1743, 1986). The role of these forms in controlling cyclic nucleotide levels and smooth muscle tone was investigated by the use of PDE inhibitors. The effects of selective inhibitors of the two forms specifically hydrolyzing cAMP or cGMP (cAMP-PDE and cGMP-PDE, respectively) were compared to those of non-selective inhibitors of the three aortic PDE forms, including the calmodulin-sensitive one (CaM-PDE). Relaxation responses and accumulation of tissue cAMP and cGMP induced by these drugs were studied in precontracted rat isolated aorta, and compared to the effects of isoprenaline and forskolin (stimulants of adenylate cyclase) or sodium nitroprusside (SNP) and sodium azide (stimulants of guanylate cyclase). The eight PDE inhibitors tested all relaxed aorta with potencies that correlated with their potencies as inhibitors of cAMP-PDE, but not of cGMP-PDE. At a concentration producing half-maximal relaxation, all PDE inhibitors induced a moderate but significant accumulation of cAMP, which was comparable to the accumulation of cAMP elicited by half-maximally relaxing concentrations of adenylate cyclase stimulating agents. At this concentration, some PDE inhibitors (M&B 22,948, dipyridamole and to a lesser extent, trequinsin) also induced a significant increase in cGMP levels, of the same order of magnitude as that caused by agents stimulating guanylate cyclase. However, the cGMP-increasing effect of these inhibitors was dissociated from their relaxing effect. In particular, the relaxing concentrations of M&B 22,948 (a selective inhibitor of cGMP-PDE) were clearly higher than the cGMP-increasing concentrations of the compound. At a concentration at which they elicited 10% relaxation by themselves, the selective cAMP-PDE inhibitor, rolipram, as well as the mixed inhibitor of cAMP- and cGMP-PDE, AAL 05 (a cilostamide analogue) enhanced both the cAMP-increasing and the relaxing effect of isoprenaline. Under the same conditions, no clear enhancement of the relaxation induced by SNP was observed. Only M&B 22,948 showed a slight potentiating effect on SNP-induced relaxation, but this effect was limited to low concentrations of SNP (less than 10 nM).(ABSTRACT TRUNCATED AT 400 WORDS)

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

Cyclic AMP and cyclic GMP phosphodiesterase activities in Hodgkin's disease lymphocytes.

Cyclic nucleotide phosphodiesterase (PDE) activities were studied in peripheral blood monocyte-depleted lymphocytes and enriched T-lymphocyte suspensions from thirteen patients with previously untreated Hodgkin's disease (HD) and fourteen age and sex matched healthy volunteers. Monocyte-depleted lymphocytes from HD patients showed PDE-activities which were two times higher than in their normal counterpart cells. The mean cAMP-PDE activity present in enriched HD T-lymphocyte suspensions was four times higher than in control T-lymphocytes, and the mean cGMP-PDE associated with HD T-lymphocytes was three times higher than in the controls. The hydrolytic activities present in both monocyte-depleted and T-lymphocyte enriched cells suspensions remained unchanged in absence or in the presence of calmodulin and calcium. Since depressed cAMP and cGMP resting levels have been observed in HD lymphocytes and lymphocyte subpopulations, our results suggest that the elevated PDE activities are, at least in part, responsible for the alterations in lymphocyte cyclic nucleotide levels.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1986

Selective inhibition of cyclic nucleotide phosphodiesterases of human, bovine and rat aorta.

Cyclic nucleotide phosphodiesterase (PDE) activity from the 105,000 g supernatant of human, bovine and rat aorta smooth muscle cells was resolved by DEAE-trisacryl chromatography into three major forms showing similar properties in each species. In addition to the two PDE forms previously characterized in vascular tissues (a cAMP-PDE and a calmodulin-dependent PDE), a cGMP-PDE, insensitive to calmodulin, was isolated and characterized in the aorta of the three species. Each isolated PDE form was differently inhibited by various chemical compounds, and these compounds produced effects on cyclic nucleotide levels in isolated rat aorta which could be expected from their inhibitory effect on isolated PDE forms. At concentrations non-selectively inhibiting the three isolated PDE forms (including the calmodulin-dependent one), IBMX (3-isobutyl-1-methylxanthine) and trequinsin markedly and dose-dependently increased both cAMP and cGMP aorta levels (up to 7-fold, in presence of 500 microM IBMX). By contrast selective inhibitors of cGMP-PDE or cAMP-PDE could only induce a moderate elevation (by 1.5-3-fold) in cGMP or cAMP levels, respectively. In the case of M&B 22,948, a highly specific and potent inhibitor of cGMP-PDE, a concentration-dependent increase in tissue cGMP levels was produced by concentrations (in the microM range) active in inhibiting the isolated enzyme. In the case of selective cAMP-PDE inhibitors (rolipram and Ro 20-1724), however, a significant increase in aorta cAMP content was induced only in the presence of drug concentrations which were much higher (200 and 500 microM, respectively) than those inhibiting the isolated enzyme (IC50:5 and 18 microM, respectively). Inhibitors of both cGMP-PDE and cAMP-PDE (dipyridamole, cilostamide and its derivative AAL 05) produced the same moderate effects as did the combination of a selective cGMP-PDE inhibitor and a selective cAMP-PDE inhibitor on the levels of both cGMP and cAMP. These results show that the three forms of PDE isolated from aortic smooth muscle retain properties that they exhibit in the tissue and which are similar in the three species examined, including man. They suggest that each form participates in a specific manner to the regulation of cAMP and cGMP concentrations in aorta smooth muscle cells.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Tissue and substrate specificity of inhibition by alkoxy-aryl-lactams of platelet and arterial smooth muscle cyclic nucleotide phosphodiesterases relationship to pharmacological activity.

Alkoxy-aryl-lactams (cilostamide, AAL 05, ZK 62 711, Ro 20-1724) inhibit differently cAMP or cGMP phosphodiesterases from blood platelets or vascular smooth muscle. Cilostamide (IC50 0.23 microM) and AAL 05 (IC50 0.15 microM) are 100 times more potent towards platelet cAMP phosphodiesterase whereas ZK 62 711 (IC50 2 microM) and Ro 20-1724 (IC50 33 microM) inhibit more selectively the enzyme from aorta. The substrate specificity of the inhibitors is different in the two tissues: ZK 62 711 and cilostamide are respectively 345 and 290 times more potent as inhibitor of cAMP than cGMP phosphodiesterase from vascular smooth muscle (ZK 62 711) or platelets (cilostamide). M + B 22,948 selectively inhibits cGMP phosphodiesterase with an IC50 of 9 or 24 microM on platelet or aorta enzyme, respectively. In general, the potencies of spasmolytic and platelet inhibitor effects vary from one drug to the other with the potency of inhibition of phosphodiesterase from the corresponding tissue. These data suggest that phosphodiesterases from platelets are different from those of arterial smooth muscle.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Variations in endogenous phosphodiesterase activator content of rat aorta.

The variations with age and blood pressure in the cyclic nucleotide phosphodiesterase activator content of rat aorta were studied. Activator content increased with age and was less in mineralocorticoid-hypertensive than in control rats. These variations were more pronounced in the particulate than in the soluble fraction of aorta. The data do not demonstrate any relationship between the activator level and blood pressure, but they suggest that the activator may modulate cyclic nucleotide metabolism in rat aorta.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

Cyclic nucleotide hydrolysis in bovine aortic endothelial cells in culture: differential regulation in cobblestone and spindle phenotypes.

Cyclic nucleotide phosphodiesterases (PDEs) were investigated in cultured bovine aortic endothelial cells having two phenotypes, cobblestone and spindle, representing, respectively, the resting and angiogenic phenotypes in vivo. Spindle cell homogenates displayed higher hydrolytic activities towards cAMP (52%) and cGMP (10-fold). These increases were due to: (1) increased number of spindle PDE isozymes in the cytosolic fraction (for cAMP: PDE1, PDE2, PDE3 and PDE4 compared to PDE2 and PDE4 in cobblestone; for cGMP: PDE2 and PDE5 compared to PDE2 in cobblestone); (2) increased spindle-specific activities of cytosolic and particulate PDE2, cytosolic PDE3 and particulate PDE4. These changes were associated with an increase in spindle transcripts: 7.5 kb PDE3A (6-fold) and 7.0 kb PDE4D (3-fold). Moreover, cAMP hydrolysis in the two phenotypes was differently regulated by 5 microM cGMP: 60% increase in total cAMP-PDE activity in cobblestone homogenate related to PDE2 stimulation; 30% decrease in spindle homogenate related to PDE3 inhibition. This underlines the roles played by PDE2, PDE3 and PDE5 in the cross-talk involving the two cyclic nucleotides. These changes in PDE isozyme expression along with the cross-talk between cAMP and cGMP may well modulate NO production and consequently might participate in angiogenesis, making PDEs potential targets to modulate angiogenesis.

3',5'-Cyclic-AMP Phosphodiesterases↗