Effects of zinc on cardiac muscle contraction

¹ Baker Medical Research Institute, Melbourne, Australia

The effect of 0.001^–5 mm Zn⁺⁺ on the contractions of dog, rabbit, and monkey papillary muscles, rat atria, isolated rat hearts, and toad and tortoise ventricular muscle was investigated. Zn⁺⁺ depressed the contractions of all cardiac muscle preparations tested; the negative inotropic response was associated with an unchanged duration of contraction and a prolonged action potential. Zn⁺⁺ > 0.5 mm caused mechanical arrest; perfusion of Zn⁺⁺-arrested amphibian preparations with 100 mm K⁺ solution resulted in contractures equal in magnitude to that evoked by similar perfusion with 100 mm K⁺ in the absence of Zn⁺⁺. It is concluded that the action of Zn⁺⁺ on cardiac muscle differs essentially from that described for skeletal muscle.

Key Words: cardiac contractile activity • Zn and cardiac contractions • excitation-contraction coupling

Submitted on August 31, 1964