Abstract
Summary
1. Summation of contractions and incomplete tetanus may be consistently produced in frog ventricle strips by elevation of bath temperature. In these experiments a temperature of about 30° C regularly induced the summated response. 2. Digitoxin in cone, of 0.3 μg/ml potentiated the summated response and caused its appearance at lower temperatures. 3. Epinephrine in cone, of l0-6 prevented summated response to digitoxin or high temperature. 4. The summated response to digitoxin or high temp. is associated with reduction in duration of refractory period and the inhibitory effect of cooling or epinephrine with increase in duration of refractoriness. 5. Rat ventricle strips may show summation, incomplete tetanus and post-tetanic potentiation at temp. of 38° C and in the absence of treatment with drugs. The mechanisms of these phenomena are not yet delineated.
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