Abstract
The inotropic response of the isolated papillary muscle of the cat's right ventricle has been studied in relation to increasing concentrations of "cardiac glycoside." In a series of congeners of digitoxin it has been possible to obtain characteristic and reproducible results under certain specified conditions. Among the essential conditions is the preliminary production of a hypodynamic state; fresh muscle will not respond to digitoxin congeners in the "therapeutic" range of concentration. After calibration with a ouabain standard each individual papillary muscle can be assigned its own muscle constant, a. Then the fractional response, R, to any glycoside G, follows the equation:
log G + log M + log a = 0.5 log < R/(1 - R) >
where log M is the negative log-potency of the glycoside.
Footnotes
- Received December 10, 1947.
- 1948 by The American Society for Pharmacology and Experimental Therapeutics
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