Metabolic effects of intramuscular and oral administration of ritodrine in pregnancy.

The metabolic effects of ritodrine, 80 mg/day, administered intramuscularly in the third trimester of pregnancy to 14 patients for 5 days and per os to 10 patients for 10 days were investigated. Each patient was considered at high risk for premature labor. Intravenous glucose tolerance and insulin, triglyceride, and electrolyte levels were assessed before and at the end of treatment with ritodrine. Intramuscularly or orally administered ritodrine in 10-mg doses 8 times a day did not influence carbohydrate homeostasis. Triglyceride levels fell significantly after intramuscular administration, whereas serum potassium levels increased during treatment. This study suggests that ritodrine administered intramuscularly or orally is metabolically safe in nondiabetic pregnant women.

The central responsiveness of the acute cerveau isolé rat.

The electrophysiological patterns of the frontal cortex and dorsal hippocampus were studied in the acute cerveau isolé rat. Central and peripheral stimulations were performed in order to modulate these patterns. The results showed that the permanent alternation of high amplitude spindle bursts and low voltage activity in the anterior neocortex of the acute cerveau isolé was influenced neither by olfactory nor by posterior hypothalamic stimulation. In contrast, these two kinds of stimulation easily modulated the continuous low frequency theta rhythm, recorded in the dorsal hippocampus, in terms of amplitude and in overall frequency. This modulation of the theta rhythm in the acute cerveau isolé rat mimics the changes observed when the normal rat comes from the intermediate stage of sleep (as characterized in the the acute intercollicular transected rat by high amplitude spindle bursts at frontal cortex level and low frequency theta activity in the dorsal hippocampus) to rapid sleep. These results further suggest that, during the intermediate stage (as in the cerveau isolé preparation), the hippocampus montonous theta activity appears through a brainstem disinhibitory process releasing the forebrain limbic pacemaker(s). During the following rapid sleep phase, the theta rhythm would be modulated by pontine activity influences acting on the theta generators.

Metabolic effects of intravenous ritodrine infusion during pregnancy.

The effect of intravenous administration of ritodrine on blood glucose, insulin, free fatty acids and electrolytes in 17 third-trimester gravidas was investigated. A highly significant increase in blood glucose, insulin and free fatty acids and a marked decrease in serum potassium levels were registered. No significant changes during ritodrine infusion were recorded in serum levels of sodium, chloride, calcium, phosphorus and magnesium. No cardiac arrhythmias or electrocardiographic deteriorations occurred. While intravenous ritodrine administration seems to be safe in normal pregnancy, there may be a risk in diabetic patients, digitalized cases and those patients being treated with diuretics.

The acute pretrigeminal rat.

In five rats the brainstem was transected at the pretrigeminal level. In the frontal cortex, desynchronized EEG activity dominated, while in the dorsal hippocampus theta activity of low frequency (about 4 cycle/s) was almost continuously present. Olfactory and visual stimuli and electrical stimulation of the posterior hypothalamus induced or increased cortical EEG desynchronization and increased the regularity and the frequency of the theta activity in the hippocampus. However, visual stimuli were effective only in three rats. Ocular responses (pupillary dilatation, eye movements) were never observed to any stimulation. It is suggested that similarly as in the pretrigeminal cat, the isolated cerebrum is awake in the pretrigeminal rat.

Intermediate stage of sleep and acute cerveau isolé preparation in the rat.

The acute cerveau isole rat shows spindle bursts of large amplitude alternating with low voltage activity in the frontal cortex and continuous theta rhythm in the dorsal hippocampus. These patterns closely resemble an "intermediate" stage of sleep-waking cycle, when the forebrain structures seem to be functionally disconnected from the brainstem.

Sleep: a physiological "cerveau isolé" stage?

Rapid or paradoxical sleep in the rat is usually preceded and often followed by a stage of short duration characterized by large spindles in the frontal cortex and theta rhythm in the hippocampus. The midbrain transection induces for hours the same electrophysiological patterns suggesting the existence in the rat of a short physiologically isolated, forebrain stage during sleep.