Effects of autonomic drugs on the cardiovascular system: dogs with achalasia (under halothane anesthesia)

Abstract

The parasympathetic and sympathetic components of the autonomic systems as they relate to cardiovascular function were studied on dogs with achalasia of the esophagus. This was accomplished by administering the parasympathomimetic drugs methacholine (0.2 mg/kg, subcutaneously), 2 doexy-D-glucose (100 mg/kg, intravenously (IV), the parasympatholytic drug atropine (0.2 mg/kg, IV), the sympathomimetic agent epinephrine (2.5 microng/kg, IV), and the beta adrenergic blocker propranolol (0.5 mg/kg, IV); and then measuring cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, PaCO2, PaO2, pH, and base deficit. Cardiovascular responses to the administration of the parasympathomimetic drugs, methacholine and 2 deoxy-D-glucose, or the parasympatholytic drug, atropine, were similar to those observed in normal dogs. Cardiovascular responses to the administration of the sympathomimetic drug epinephrine and the sympatholytic drug propranolol or beta blocker were also consistent with those observed in normal dogs. It can be interpreted from this pharmacologic evidence that parasympathetic and sympathetic innervations to the cardiovascular system are present in dogs with achalasia of the esophagus. Fewer cardiovascular variables were significantly altered in dogs with achalasia than in normal dogs. Since this was true for both the sympathetic and the parasympathetic values, it is interpreted as reflecting their general health rather than a specific lesion.