Much attention has been directed in recent years to the effects of altered pH and partial pressure of arterial carbon dioxide (Pco2) on the action of exogenous catecholamines and other cardiotonic drugs in the presence of hemodynamic shock.1,2 Few references, however, are available regarding the action of isoproterenol hydrochloride in the presence of an altered acid-base status.
This laboratory study utilized an experimental format previously used to define the hemodynamic effects of altered pH and Pco23 and adds to it evaluation of the hemodynamic response to a single 100μg injection of isoproterenol hydrochloride. The ultimate aim of the study was to obtain more data on the mode of action of isoproterenol so that its clinical application could be better appreciated.
Methods
Male holstein calves (mean weight, 63 kg [138.6 lb]) were lightly anesthetized with ether and complete respiratory paralysis obtained with an intravenous injection of 20