Amiodarone and thyroid function.

Amiodarone blocks the action of thyroid hormone by the inhibition of 5'-deiodinase which reduces production of T3 in peripheral tissues and possibly by blocking nuclear binding of T3. Since the drug inhibits peripheral conversion of T4 to T3, many patients taking amiodarone have abnormal thyroid function studies (increased T4 and rT3; decreased T3) despite being euthyroid. Treatment of patients with amiodarone generates an iodine excess, which contributes greatly to the significant incidence of altered thyroid status in this population.

In vitro electrophysiologic properties of amrinone in mammalian cardiac tissue.

We studied the actions of amrinone on transmembrane electrical activity in isolated normal and physiologically compromised mammalian cardiac Purkinje and ventricular tissues. No arrhythmogenic effects of amrinone were identified in canine Purkinje tissue superfused with concentrations of 18.7 and 187 micrograms/ml (10(-4) and 10(-3) M) or in feline papillary tissue at concentrations of 18.

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.

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.