Nov 1, 1975

Effects of verapamil on the blood-perfused, isolated atrium preparation of the dog heart

Japanese Heart Journal
S Chiba


Thirteen isolated canine right atria were perfused with blood conducted from a support dog. The selective injection of verapamil into the cannulated sinus node artery at a dose level above 1 mug usually induced dose-dependent negative chronotropic and negative inotropic effects. At a dose of 30 mug, verapamil caused sinus arrest in 4 cases out of 7 with marked suppression of the isometric tension development. At 100 mug, in all cases it caused sinus arrest which continued about 1 hour. When calcium chloride was injected into the sinus node artery, a positive inotropic effect was dose-relatedly produced above a dose level of 100 mug, but the threshold dose for inducing a positive chronotropic effect of calcium chloride was approximately 1 mg. On the other hand, norepinephrine when injected into the sinus node artery simultaneously induced a positive chronotropic and inotropic effect at the same threshold dose. A dose level of 10-30 mug of verapamil did not significantly inhibit positive chronotropic and inotropic responses to norepinephrine and a positive inotropic response to calcium chloride in per cent. The negative inotropic response as well as the positive chronotropic and inotropic responses to electric stimulation of the ...Continue Reading

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Mentioned in this Paper

Sinoatrial Node
Myocardial Contraction
Atrial Standstill
Norepinephrine, (+, -)-Isomer
Right Atrial Structure
Visual Suppression
Calcium Chloride, Anhydrous
Body Surface Area Formula for Dogs

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