The inhibitory effects of amrinone on isolated rat uterus.

Amrinone, a new cardiotonic drug, has received attention as a better therapeutic agent than the cardiac glycosides in the treatment of congestive heart failure. In this study, the effects of amrinone on isolated rat uterus and its probable mechanism of action were investigated. At two different concentrations (0.1 and 0.5 mM), the inhibitory effects of amrinone on the spontaneous contractions of rat uterus were noted. In addition, amrinone (0.5 mM) was found to inhibit the tonic contractions induced by potassium sulphate (K2SO4)-Ringer solution (91.74%) and calcium chloride (CaCl2) (93.04%). These inhibitory effects were compared with regulators of the phosphodiesterase enzyme (PDE). It was concluded that amrinone could behave as a calcium antagonist and PDE inhibitor.

Intermittent tremor-bursts induced by chlorpromazine and pentobarbitone in guinea pigs: a new tremor model.

It was discovered by serendipity that a combined application of chlorpromazine (3.5 mg/kg) and pentobarbitone (20.0 mg/kg) induced intermittent tremor-bursts in four extremities of guinea pigs. This tremor with a prominent extensor activity disappeared after spinalization, indicating a supraspinal process. Biperiden reduced the frequency and amplitude of the tremor, which was further diminished by amantadine. Baclofen was found to be most potent drug in suppressing tremor. It was suggested that the cortico-striato-pallido-thalamo-cortical feedback loop may be impaired by a combined action of chlorpromazine and pentobarbitone. This new animal model for drug-induced tremor would be of considerable importance with regard to physiological, biochemical, pharmacological and pathological aspects of motor control.