Assessment of “Ca2+-antagonist” effects of drugs in K+-depolarized smooth muscle

@article{Spedding2004AssessmentO,
  title={Assessment of “Ca2+-antagonist” effects of drugs in K+-depolarized smooth muscle},
  author={Michael Spedding},
  journal={Naunyn-Schmiedeberg's Archives of Pharmacology},
  year={2004},
  volume={318},
  pages={234-240}
}
  • M. Spedding
  • Published 1 February 1982
  • Chemistry, Medicine
  • Naunyn-Schmiedeberg's Archives of Pharmacology
Summary1.Taenia preparations from the guinea-pig caecum yielded reproducible concentration-response curves to Ca2+ (EC 50 134±8 μmol/l) when maintained in depolarizing Tyrode solution containing K+ (40 mmol/l). Drugs which are claimed to be “Ca2--antagonists” displaced the curves to the right without depression of the maximum response. In this test nifedipine, verapamil, diltiazem, pimozide, cinnarizine, flunarizine and fendiline appeared qualitatively similar but had different potencies.2.The… 
Interactions between a “calcium channel agonist”, Bay K 8644, and calcium antagonists differentiate calcium antagonist subgroups in K+-depolarized smooth muscle
  • M. Spedding, C. Berg
  • Chemistry, Medicine
    Naunyn-Schmiedeberg's Archives of Pharmacology
  • 2004
TLDR
Bay K 8644 increased the sensitivity to Ca2+ of K+-depolarized taenia preparations from the guinea-pig caecum and defined subgroups of calcium antagonists which are the same as those previously reported from functional studies.
Competitive interactions between Bay K 8644 and nifedipine in K+ depolarized smooth muscle: a passive role for Ca2+?
  • M. Spedding
  • Chemistry, Medicine
    Naunyn-Schmiedeberg's Archives of Pharmacology
  • 2004
TLDR
Bay K 8644 was a non-competitive antagonist of the inhibitory effects of verapamil and diltiazem on Ca2+-induced contractions and is shown to be a powerful tool discriminating between them.
Compared effects of calcium entry blockers on calcium-induced tension in rat isolated cerebral and peripheral resistance vessels
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While Ca2+-induced contractile responses were inhibited in a similar non-competitive manner by the four CEB's, the respective IC50 values showed that potencies and rank of relative potency of the blockers were different in the two types of vessels.
Rate of L-type calcium channels on yohimbine-precipitated clonidine withdrawal in vivo and in vitro
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Blockade by zinc ions of K+-induced contraction and calcium in guinea pigTaenia coli
  • T. Nasu
  • Biology, Medicine
    Experientia
  • 2005
Preincubation with 0.3 mM Zn2+ markedly inhibited both the tonic response and Ca2+ binding at low affinity sites induced by K+ (60 mM), with smaller effects on the phasic response and the high
Effect of calcium antagonists (ω-conotoxin GVIA, verapamil, gallopamil, diltiazem) on bronchial smooth muscle contractions induced by soman
TLDR
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The comparative pharmacology of these peptides and of some analogues of the originally described endothelin have revealed some surprising differences and may indicate the existence of different endothelins receptors.
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