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The inhibitory effect of newer calcium antagonists (nimodipine and PY-108-068) on vasoconstriction in vivo mediated by postsynaptic alpha 2-adrenoceptors

Van Meel, J. C. A., Wilffert, B., De Zoeten, K., Timmermans, P. B. & Van Zwieten, P. A., Dec-1982, In : Archives internationales de pharmacodynamie et de therapie. 260, 2, p. 206-17 12 p.

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  • J. C. A. Van Meel
  • B Wilffert
  • K De Zoeten
  • P B Timmermans
  • P A Van Zwieten

In the pithed rat, stimulation of postsynaptic alpha 1 as well as alpha 2-adrenoceptors is known to cause vasoconstriction. The two newer nifedipine-related calcium antagonistic agents nimodipine and PY-108-068 proved potent inhibitors of pressor responses induced by the selective alpha 2-receptor agonist B-HT 920. The maximal pressor effect of B-HT 920 was significantly reduced, whereas the hypertensive effects brought about by selective postsynaptic alpha 1-adrenoceptor stimulation were, but slightly, impaired by nimodipine and PY-108-068 and the maximal increase in diastolic pressure was not affected by the calcium antagonists. Under beta-blockade and suppression of alpha 1-adrenoceptor-mediated vasoconstrictor effects by prazosin, the resulting alpha 2-adrenoceptor-induced vasopressor response to (-)-norepinephrine proved also very sensitive towards the inhibitory action of nimodipine and PY-108-068. In comparison with nifedipine, PY-108-068 was 3.9 and nimodipine 5.1-times more potent with respect to reducing vasopressor responses of B-HT 920.

Original languageEnglish
Pages (from-to)206-17
Number of pages12
JournalArchives internationales de pharmacodynamie et de therapie
Volume260
Issue number2
Publication statusPublished - Dec-1982

    Keywords

  • Animals, Azepines, Blood Pressure, Calcium Channel Blockers, Heart Rate, Male, Methoxamine, Nicotinic Acids, Nifedipine, Nimodipine, Norepinephrine, Pyridines, Rats, Rats, Inbred Strains, Receptors, Adrenergic, Receptors, Adrenergic, alpha, Vasoconstriction

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