Effect of the Ca2+ antagonist lidoflazine on normoxic and anoxic contractions of canine coronary arterial smooth muscle

Anoxia augments contractions of isolated canine coronary arteries to 5-hydroxytryptamine and norepinephrine. Lidoflazine inhibits normoxic contractions to both monoamines and the further increases in tension seen with anoxia in rings exposed to 5-hydroxytryptamine; further increases in tension caused by anoxia in presence of norepinephrine were not affected by lidoflazine. These experiments demonstrate that anoxia can cause constriction of large coronary arteries and that lidoflazine depresses both anoxic and normoxic contractions of coronary smooth muscle.link_to_subscribed_fulltex

Vascular effects of the serotonergic antagonist R 41 468

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Improvement of tissue perfusion with inhibitors of calcium ion influx

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Serotonin and vascular function

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Calcium entry blockers and vascular smooth muscle heterogeneity

Inasmuch as the cytoplasmic level of activator Ca2+ governs the contractile activity of vascular smooth muscle cells, the efficacy of calcium entry blockers in curtailing vasoconstriction is determined by the dependency of this level on the influx of extracellular Ca2+ into the cells; this dependency varies with the trigger to contraction as well as with the anatomical origin of the vascular preparation tested. Certain calcium entry blockers (e.g. flunarizine and lidoflazine) tested in experimental conditions triggering the influx of the activator ion exhibit a pronounced tissue selectivity, presumably because the characteristics and accessibility of the Ca2+ channels vary among different vascular smooth muscle cells. The time of onset and duration of calcium entry blockade are not identical for all calcium entry blockers, which must reflect their permeation in the tissue as well as their individual pharmacological properties at the molecular level.link_to_subscribed_fulltex

Ketanserin - a novel antihypertensive drug

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Selectivity of calcium antagonism and serotonin antagonism with respect to venous and arterial tissues

Differences of arterial and venous smooth muscle tissues in their sensitivity to Ca2+ antagonists and to serotonin antagonists were studied in a number of blood vessels. The tissue selectivity for Ca2+ antagonists, in particular differences between arteries and veins is related both to the presence of extra- and intracellular pools from which Ca2+ ions are mobilized and to differences in access to or sensitivity of the Ca2+ channels in various vascular tissues. Tissue selectivity also exists for serotonin as well as for serotonin antagonists of which R 41 468 is an example of a compound with high selectivity for vascular tissues.link_to_subscribed_fulltex

Cardiovascular pharmacology of ketanserin.

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Inhibition by met enkephalin of peristaltic activity in the guinea pig ileum, and its reversal by naloxone

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Effect of Ca2+-entry blockade and serotonergic antagonism on contractions of hypoxic isolated canine coronary arteries

Lidoflazine, flunarizine, and R 51 469 antagonized contractions of isolated canine coronary arteries caused by depolarizing solution or 5-hydroxytryptamine, and the further increase in tension caused by hypoxia during such contractions. The 5-HT2-antagonist ketanserin, but not methysergide, antagonized contractions induced by 5-hydroxytryptamine, but not those by high K+; it reduced further increases in tension caused by hypoxia only during contractions caused by 5-hydroxytryptamine. Augmentation by hypoxia of coronary vasoconstriction appears to be a Ca2+-dependent phenomenon.link_to_subscribed_fulltex