Abstract
The time course of the inotropic response to ouabain in Langendorff preparations was compared with that of the in vitro ATP-dependent (3H)-ouabain binding to cardiac (Na++K+)-activated ATPase preparations, and subsequent dissociation, to determine the temporal relationship between the inotropic response and (Na++K+)-activated ATPase inhibition. Species differences were minimal either in the onset of inotropic response or the (3H)-ouabain binding. The rates of both loss of the inotropic response to ouabain during washout and the dissociation of the ouabain-enzyme complex, however, were rapid in guinea pig and rabbit (relatively ouabain-insensitive species) and slow in cat and dog (ouabain-sensitive species). The half-time of the loss of the inotropic response was similar to the half-time of the dissociation of the ouabain-enzyme complex in each species. Since ATP-dependent binding of cardiac glycosides has been related to enzyme inhibition, it was concluded that the time course of the inotropic response to ouabain parallels the time course of (Na++K+)-activated ATPase inhibition, and that the dissociation of ouabain from the enzyme may terminate the inotropic response.
Original language | English |
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Pages (from-to) | 151-162 |
Number of pages | 12 |
Journal | Naunyn-Schmiedeberg's Archives of Pharmacology |
Volume | 277 |
Issue number | 2 |
DOIs | |
State | Published - Jun 1973 |
Keywords
- (Na+K)-Activated ATPase
- Cardiac Glycosides
- Positive Inotropic Effect
ASJC Scopus subject areas
- Pharmacology