Význam magnézia a kalciapro nervové funkce

Significance of Calcium and Magne-sium for the Neural Functions

Roles of calcium and magnesium in the nervous tissues has been frequentlydiscussed. Magnesium is sometimes denoted as „the forgotten cation“ foralthough it is the second most common intracellular cation, the study of itshomeostasis and regulatory functions has long been neglected. However, atpresent it becomes evident, that not only calcium but also magnesium has animportant regulatory function in the intracellular mechanisms.Beside the assured effect of these cations on the permeability of sodium andpotassium channels, the intracellular magnesium has an important blockingeffect on the low-threshold voltage-gated calcium channels. In the centralnervous system, magnesium participates in the control of glutamate recep-tors-channels. It affects N-methyl-D-aspartate receptors (NMDA), which, con-trary to non-NMDA receptors, are intensively regulated by this cation. Thisblocking effect is induced both by the intracellular and extracellular magne-sium. Similarly important role in the control of sensitivity of the NMDAreceptors has calcium.Calcium in the nervous tissue has many other functions. If affects permeabi-lity and sensitivity of neuronal membranes, it mediates the neurotransmitter release into the synaptic cleft, it has a direct relation to the control of sensiti-vity of the postsynaptic apparatus, it modulates the transmission and integ-ration properties of dendrites (especially in the necks of dendritic spines),and it participates on the process of organisation and plasticity of neuronalcircuits (activity of growing cones, apoptosis) etc.

Key words:
magnesium, calcium, nervous system, transport systems,homeostasis.