Perfusion-time-dependent appearance of blocking effect of diltiazem on norepinephrine-induced vasoconstriction in isolated, perfused dog pulmonary veins.
Time-dependent changes in the blocking effect of diltiazem on norepinephrine (NE)-induced vasoconstrictions were investigated in isolated canine pulmonary veins. Within 2-3 hr of the perfusion period, pretreatment with diltiazem did not affect the vasoconstrictor responses to NE. However, in the 8-11 hr perfused preparations, diltiazem suppressed the NE-induced vasoconstriction significantly. It may participate in the mechanisms for the appearance of the blocking effect in the following manner: 1) a proportion of alpha adrenoceptors which are sensitive to calcium entry are increased and/or 2) spare alpha adrenoceptors are decreased time-dependently.
Haniuda
M
M
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
Chiba
S
S
D000818:Animals; D004110:Diltiazem / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000502:physiology; D010477:Perfusion; D011433:Propranolol / Q000494:pharmacology; D011667:Pulmonary Veins / Q000187:drug effects*; D011799:Quinazolines / Q000494:pharmacology; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*
D007093:Imidazoles; D011799:Quinazolines; C032368:midaglizole; C018176:bunazosin; D011433:Propranolol; D004110:Diltiazem; D009638:Norepinephrine