Perfusion of a strip of mammalian ventricle; effects of K-rich and Na-deficient solutions on transmembrane potentials.

A preparntion of sheep's or calf's myocardium is described: the m. transversus cordis of the right ventricle. This lends itself to perfusion of its capillary bed as well as to the recording of membrane potentials from single fibers. When the Na concentration in the perfusate is reduced, the action potentials undergo changes that suggest that the •'•'sodium hypothesis" is applicable to cardiac ventricle.