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THE EFFECTS OF DILTIAZEM (CRD‐401) ON THE MEMBRANE AND MECHANICAL PROPERTIES OF VASCULAR SMOOTH MUSCLES OF THE RABBIT
Author(s) -
ITO YUSHI,
KURIYAMA HIROSI,
SUZUKI HIKARU
Publication year - 1978
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1978.tb17311.x
Subject(s) - diltiazem , depolarization , contraction (grammar) , vasodilation , vascular smooth muscle , membrane potential , muscle contraction , stimulation , chemistry , myogenic contraction , medicine , biophysics , anesthesia , calcium , smooth muscle , biology
1 The effects of diltiazem on electrical and mechanical properties of vascular smooth muscles of the rabbit were examined by various experimental procedures. 2 In the pulmonary artery, diltiazem (0.1 to 10 μg/ml) did not modify the membrane potential (‐56 mV), length constant of the tissue (1.47 mm) or rectifying properties of the membrane. Diltiazem (0.1 to 10 μg/ml) did not modify the membrane potential of the mesenteric artery (‐62.5 mV). 3 Diltiazem (1 to 10 μg/ml) suppressed mechanical responses of pulmonary and mesenteric arteries induced either by direct stimulation of the muscle (1.0 s pulse) or by neural activation (0.5 ms pulse, 30 Hz and 10 s total duration). Diltiazem suppressed the contraction induced by nerve stimulation to a greater extent than that induced by direct muscle stimulation. 4 When the depolarization‐contraction relationship of the smooth muscle of the pulmonary artery was observed by voltage clamp technique, diltiazem (1 to 10 μg/ml) raised the critical membrane potential to evoke contraction from 5 mV to 12 mV, and reduced the amplitude of contraction obtained at any given depolarization level. 5 In the pulmonary artery, diltiazem (10 μg/ml) suppressed K‐induced contraction and raised the mechanical threshold, while K‐induced depolarization was not suppressed. Diltiazem (1 to 10 μg/ml) also suppressed noradrenaline‐induced contraction, raised the mechanical threshold and suppressed noradrenaline‐induced depolarization. 6 The vasodilator actions of diltiazem on the vascular smooth muscle were compared to vasodilator actions observed with other Ca‐antagonists.