Open AccessPotential-Dependent Interactions of Nitrendipine and Related 1,4-Dihydropyridines in Functional
Author(s) -
David Triggle,
M. Hawthorn,
Wei Zheng
Publication year - 1988
Publication title -
journal of cardiovascular pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 100
eISSN - 1533-4023
pISSN - 0160-2446
DOI - 10.1097/00005344-198806124-00018
Subject(s) - nitrendipine , nifedipine , antagonist , diltiazem , chemistry , potency , pharmacology , guinea pig , extracellular , smooth muscle , ic50 , medicine , biophysics , calcium , in vitro , biology , biochemistry , receptor , organic chemistry
Interaction of nitrendipine and other Ca2+ channel antagonists including nifedipine, diltiazem, and D600 with intestinal smooth muscle was shown to depend on membrane potential. In the absence of extracellular Ca2+, guinea pig ileal longitudinal muscle does not contract and can be incubated at various K+ concentrations in the presence or absence of antagonist. Preincubation with elevated K+ prior to admission of Ca2+ and challenge with K+ to a total of 100 mM increased the activity of the antagonist. The IC50 for nitrendipine incubated in the presence of 5 mM K+ was 5.36 X 10(-9) M and in the presence of 40 mM K+ was 0.53 X 10(-9) M. Other 1,4-dihydropyridines showed similar potency shifts.