J F Healey — Page 3 | PubMed Health

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Intrathecal tolerance of metrizamide in chloralose anesthetized cats.

The water soluble radiopaque medium, metrizamide (Amipaque) was introduced into the lumbar subarachnoid space in chloralose anesthetized cats at a standard volume of 0.35 cc/kg in concentrations of 300 mgI/cc to 500 mgI/cc during EMG recording. These animals did not differ from controls which received cerebrospinal fluid under otherwise identical conditions; both groups usually showed some mild and occasional muscle fasciculations or mild spasms. Treatment with metrizamide appeared to be a less deleterious procedure than that using hyperosmotic sucrose (1.32 M) as judged from EMG records. In contrast, equivalent amounts of neglumine iothalamate produced frank convulsions in 7 of 15 cases and a range of hyperirritability in the remaining 8.

Anesthesia↗

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Electrophysiological actions of amrinone in dogs with cardiac lesions.

We examined the actions of amrinone in five models using dogs to determine under what circumstances intravenous amrinone might exert arrhythmogenic or antiarrhythmic properties. In dogs with 24-h post-coronary artery ligation arrhythmias, amrinone, given at incrementally increasing doses of 1.5, 3.0, and 6.0 mg/kg at 30-min intervals, produced significant increases of cardiac contractility without altering the severity of the arrhythmia. In dogs with 2- to 6-day-old ischemic lesions and 90-100% sinus beats, a bolus dose of 3.0 mg/kg amrinone was followed by an increased incidence of abnormal beats (p = 0.013); neither 1.5 nor 6.0 mg/kg caused a significant incidence of arrhythmias. Acute occlusion of the left anterior descending coronary artery followed by reperfusion caused fibrillation in nine of 15 control dogs and two of 14 dogs treated with 2.3 mg/kg amrinone. This difference was significant at the level p less than 0.05. In ouabain-intoxicated dogs, amrinone at 1.0 and 3.0 mg/kg neither worsened nor improved the arrhythmias. In the atrial circus flutter arrhythmia, amrinone increased ventricular heart rate by a significantly greater amount than it increased atrial rate, suggesting that amrinone facilitates atrioventricular conduction.

Aminopyridines↗