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  • Title: Interaction of histamine with adrenergic smooth-muscle neurotransmission. II. Significance of calcium ions for the effects of histamine on contractions induced by endogenous noradrenaline.
    Author: Todorov S, Zamfirova R.
    Journal: Acta Physiol Pharmacol Bulg; 1982; 8(4):45-50. PubMed ID: 6308957.
    Abstract:
    The role of Ca2+ for the effects of histamine on contractions induced by electrostimulation has been studied on smooth-muscle organs with adrenergic neurotransmission (rat anococcygeal muscle and vas deferens). The low Ca2+-concentrations in the organ bath (below 1.8 mM) reduce the amplitude of the smooth-muscle contractions in response to electrostimulation (more markedly at the low frequency), at the same time potentiating the inhibitory action of histamine on the electrostimulation-induced contractions of the isolated preparations. Raising the Ca2+-concentration in the nutrient medium increases the magnitude of the contractions in response to electrostimulation. At the same time the high Ca2+-concentrations weaken the second (inhibitory) phase of the action of histamine on the electrostimulation-induced contractions of the smooth-muscle preparations. The potentiating action of histamine on contractions in response to electrostimulation is not essentially influenced by the changes in Ca2+-concentration. The data obtained show that Ca-ions may play a role in the mechanism of the inhibitory action of histamine on the smooth-muscle adrenergic neurotransmission, which is assumed to be mediated by presynaptic H2-histaminergic receptors.
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