Effect of nickel ions on spontaneous, electrically and norepinephrine stimulated isometric contractions in the isolated portal vein of the rat
Rubányi, G.; Inovay, J.
Acta Physiologica Academiae Scientiarum Hungaricae 59(2): 181-186
1982
ISSN/ISBN: 0001-6756 PMID: 7158372 Document Number: 183585
The effect of low concentrations (1-10 microM) of nickel (Ni2+) was studied on the spontaneous contractile activity of isolated rat portal vein preparations. To distinguish between presynaptic and postsynaptic actions, Ni2+-induced changes of isometric force development evoked either by electrical field stimulation (80V/5 cm; 1 msec; 1-32 Hz) or by exogenous norepinephrine (NE) were compared. Ni2+ inhibited spontaneous isometric force development, decreased basal tone but significantly increased the frequency of contractions. The experimental findings that inhibition of the effect of selective stimulation of adrenergic nerves was significantly more pronounced than the depression of contractions evoked by exogenous norepinephrine indicate that in addition to postsynaptic actions, Ni2+ influences presynaptic mechanisms (i.e. NE-release) in this vessel preparation.