15 documents found, page 1 of 2
Differences in the expression pattern of HCN isoforms among mammalian tissues: ...
Calejo, Ana I.; Reverendo, Marisa; Silva, Virgília S.; Pereira, Patrícia M.; Santos, Manuel A. S.; Zorec, Robert; Gonçalves, Paula P.Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play a critical role in a broad range of cell types, but the expression of the various HCN isoforms is still poorly understood. In the present study we have compared the expression of HCN isoforms in rat excitable and non-excitable tissues at both the mRNA and protein levels. Real-time PCR and Western blot analysis revealed distinct expression p...
cAMP-Mediated stabilization of fusion pores in cultured rat pituitary lactotrophs
Calejo, Ana Isabel; Jorgacevski, Jernej; Kucka, Marek; Kreft, Marko; Gonçalves, Paula P.; Stojilkovic, Stanko S.; Zorec, RobertRegulated exocytosis mediates the release of hormones and transmitters. The last step of this process is represented by the merger between the vesicle and the plasma membranes, and the formation of a fusion pore. Once formed, the initially stable and narrow fusion pore may reversibly widen (transient exocytosis) or fully open (full-fusion exocytosis). Exocytosis is typically triggered by an elevation in cytosol...
Synaptotagmin 1 is required for vesicular Ca2+/H +-antiport activity
Cordeiro, Joao Miguel; Boda, Bernadett; Gonçalves, Paula P.; Dunant, YvesA low-affinity Ca(2+) /H(+) -antiport was described in the membrane of mammalian brain synaptic vesicles. Electrophysiological studies showed that this antiport contributes to the extreme brevity of excitation-release coupling in rapid synapses. Synaptotagmin-1, a vesicular protein interacting with membranes upon low-affinity Ca(2+) -binding, plays a major role in excitation-release coupling, by synchronizing c...
Peptide hormone release monitored from single vesicles in 'membrane lawns' of d...
Stenovec, Matjaz; Gonçalves, Paula P.; Zorec, RobertIn this study we used live-cell immunocytochemistry and confocal microscopy to study the release from a single vesicle in a simplified system called membrane lawns. The lawns were prepared by exposing differentiated pituitary prolactin (PRL)-secreting cells to a hypoosmotic shear stress. The density of the immunolabeled ternary soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) comple...
Automated high-throughput screening of carbon nanotube-based bio-nanocomposites...
Gonçalves, Paula P.; Singh, Manoj K.; Silva, Virgília S.; Marques, Filipa; Marques, Ana; LeDuc, Philip R.; Grácio, José; Marques, Paula A. A. P.In this work we demonstrate the potential of using an automated cell viability analyzer for developing high-throughput screening of orthopedic bioactive materials. We used a biomaterial of carbon nanotubes (CNTs)-based composite integrated with hydroxyapatite/ polymethyl methacrylate (HA/PMMA) with controlled physical and chemical properties to evaluate the usefulness of morphometric analysis in conjunction wit...
Integrated biomimetic carbon nanotube composites for in vivo systems
Singh, Manoj Kumar; Gracio, Jose; LeDuc, Philip; Gonçalves, Paula P.; Marques, Paula A. A. P.; Gonçalves, Gil; Marques, Filipa; Silva, Virgilia S.As interest in using carbon nanotubes for developing biologically compatible systems continues to grow, biological inspiration is stimulating new directions for in vivo approaches. The ability to integrate nanotechnology-based systems in the body will provide greater successes if the implanted material is made to mimic elements of the biological milieu especially through tuning physical and chemical characteris...
Acetylcholine release and choline uptake by cuttlefish (Sepia officinalis) opti...
Nunes, M. Alexandra; Santos, Sofia; Cordeiro, J. Miguel; Neves, Paulo; Silva, Virgília S.; Sykes, António V.; Morgado, Fernando; Dunant, YvesAcetylcholine (ACh), which is synthesized from choline (Ch), is believed to hold a central place in signaling mechanisms within the central nervous system (CNS) of cuttlefish (Sepia officinalis) and other coleoid cephalopods. Although the main elements required for cholinergic function have been identified in cephalopods, the transmembrane translocation events promoting the release of ACh and the uptake of Ch r...
Comparative effects of aluminum and ouabain on synaptosomal choline uptake, ace...
Silva, Virgília S.; Nunes, M. Alexandra; Cordeiro, J. Miguel; Calejo, Ana I.; Santos, Sofia; Neves, Paulo; Sykes, António V.; Morgado, FernandoClosing the gap between adverse health effects of aluminum and its mechanisms of action still represents a huge challenge. Cholinergic dysfunction has been implicated in neuronal injury induced by aluminum. Previously reported data also indicate that in vivo and in vitro exposure to aluminum inhibits the mammalian (Na(+)/K(+))ATPase, an ubiquitous plasma membrane pump. This study was undertaken with the specifi...
The inhibitory effect of aluminium on the (Na+/K+)ATPase activity of rat brain ...
Silva, Virgília S.; Gonçalves, Paula P.The effect of AlCl3 on the (Na+ /K+)ATPase activity of freeze-thawed synaptosomes, isolated from rat brain cortex, has been studied. The AlCl3 action on the enzyme hydrolytic activity was examined using in vitro and in vivo approaches. Following exposure to AlCl3 using both in vitro (synaptosomes incubated in the presence of AlCl3 for 5 min) and in vivo (synaptosomes isolated from rats that received 0.03 g AlCl...
Aluminum accumulation and membrane fluidity alteration in synaptosomes isolated...
Silva, Virgília S.; Cordeiro, J. Miguel; Matos, Manuel J.; Oliveira, Catarina R.; Gonçalves, Paula P.In the present work, we studied the effect of cholesterol/phospholipid (CH/PL) molar ratio on aluminum accumulation and aluminum-induced alteration of membrane fluidity in rat brain cortex synaptosomes. We observed that sub-acute (daily supply of 1.00 g of AlCl3 during 10 days) and chronic (daily supply of 0.03 g of AlCl3 during 4 months) exposure to dietary aluminum leads to a synaptosomal aluminum enrichment ...