Authors:Petra Varró, Imola Szigyártó, A. Gergely, Erika Kálmán and Ildikó Világi
Carbon nanotubes are promising new tools in biomedicine but they may have yet some unknown influences on the organism. In the present study, the acute effect of solubilized, multi-walled carbon nanotubes (MWCNTs) on basic neuronal functions was examined. Rat brain slices were treated in vitro with nanotube-containing colloid solutions at concentrations of 100–800 μg/ml and evoked field potentials were recorded from the somatosensory cortex and hippocampus. Basic excitability of the treated slices was characterized by the amplitude of field excitatory postsynaptic potentials (fEPSPs) and population spikes. Experimental results indicated significantly higher excitability of treated samples than that of controls. Multiple components in evoked potentials were observed, which is in accordance with the increased excitability of investigated brain areas. Tests of short- and long-term plasticity were also performed, which revealed no difference between control and treated slices. Experimental results suggest an interaction between nanotubes and brain tissue. MWCNTs seem to act on the basic membrane potential of neurons by changing membrane properties or via a mechanism linked to voltage-gated ion channels, rather than influencing specific synaptic transmission. Further investigation is needed to clarify the nature of interactions between nanotubes and brain tissue.
Authors:András Pataricza, Z Márton, Z Hegedűs, Irén Krassói, A Kun, A Varró and J Gy Papp
Functional role of calcium-activated potassium (KCA) channels on the basal and agonist-elevated arterial tones was investigated in isolated rabbit aorta, porcine and canine coronary arteries as well as in human internal mammary artery. The vascular tones enhanced by contractile agents were increased further by preincubation of these conduit blood vessels with selective (charybdotoxin or iberiotoxin) or non-selective (tetraethylammonium) inhibitors of KCA channels. The basal tone (without an agonist) was increased only in the canine coronary artery. The results indicate a feed-back regulatory role of KCA channels counteracting the vasospasm of conduit arteries.