Studies on the role of Na, K and Cl ion permeabilities in K-induced release of H-noradrenaline from rat brain slices and synaptosomes and in its presynaptic α-adrenergic modulation.

Possible ionic mechanisms by which activation of presynaptic α-adrenoceptors might inhibit the K-induced release of H-noradrenaline from superfused rat cerebral cortex slices or synaptosomes were investigated. The data indicate that Na, K and Cl movements across the neuronal membrane are involved in the K-induced release of H-noradrenaline from brain slices and synaptosomes. However, inhibition of K-induced H-noradrenaline release by activation of presynaptic α-receptors is probably not mediated by changes in the permeabilities for either Na, K or Cl. The results of this study emphasize the pivotal role of Ca in the presynaptic α-adrenergic modulation of noradrenaline release. [ABSTRACT FROM AUTHOR]