@article {Ruffolo344, author = {R R Ruffolo, Jr and K Messick}, title = {Inotropic selectivity of dobutamine enantiomers in the pithed rat.}, volume = {235}, number = {2}, pages = {344--348}, year = {1985}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The inotropic selectivities of the (-)- and (+)-enantiomers of dobutamine were assessed in pithed rat by comparing the relative ability of each enantiomer to increase left ventricular contractility (left ventricular dp/dt) and heart rate. The (-)-enantiomer of dobutamine, which is predominantly an alpha-1 adrenoceptor agonist, displayed greater inotropic selectivity than the (+)-enantiomer, which is predominantly a beta-1 and beta-2 adrenoceptor agonist. Pretreatment with the alpha-1 adrenoceptor antagonist prazosin significantly inhibited the effect of (-)-dobutamine on left ventricular dp/dt, but did not affect the chronotropic activity of this enantiomer. As such, pretreatment with prazosin decreased the inotropic selectivity of (-)-dobutamine. In contrast, the inotropic activity and selectivity of (+)-dobutamine were not affected by prazosin pretreatment. These results indicate that the inotropic effects of (-)-dobutamine are mediated, at least in part, by alpha-1 adrenoceptors. We conclude, based on the marked inotropic activity of (-)-dobutamine and the greater inotropic selectivity of (-)-dobutamine over (+)-dobutamine, that alpha-1 adrenoceptors may play a role in the inotropic activity and selectivity of racemic dobutamine used clinically. The possible involvement of both myocardial alpha-1 and beta-1 adrenoceptors in the inotropic activity of dobutamine must be considered.}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/235/2/344}, eprint = {https://jpet.aspetjournals.org/content/235/2/344.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }