[in Japanese]

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The pharmacological properties of prolinomethyltetracycline (PM-TC) were studied and following results were obtained:
1. Effects on blood pressure and respiration.
The urethane-anaesthetized rabbits were used for the study. Intravenous administration of 10 and 40mg/kg. of PM-TC caused transient hypertensive or hypotensive effect, but the former was observed more frequently.Tachyphylaxis was observed following the successive administration of 40mg/kg of PM-TC.The respiration was inhibited when the blood pressure rose, but no effect was observed when the blood pressure fell.
2. Effects on cardiac muscle.
YAGI-STRAUB method was employed using isolated frog heart.When 0.1% solution of PM-TC was administered, the amplitude of isolated heart movement was reduced.
3. Effects on peripheral blood vessel.
The isolated auricular vessel of rabbit was used according to the KRAWKOW-PISSEMSKI method.When 0.2% solution of PM-TC was administered, decrease in blood flow was observed.
4. Effects on skeletal muscle.
The phrenic nerve-diaphragm preparation of rat was made according to the method described by TAKIUCHI. The administration of 0.01% solution of PM-TC caused a slight decrease in size of contraction, both to direct and indirect stimulation, and a concentration of 0.5% blocked completely the response to both stimulations. However when the preparation was washed throughly with fresh KREBSRINGER solution, both responses recovered completely to the control level.
5. Effects on cholinesterase and monoamine oxidase.
Homogenate of the brain of rats was used as an enzyme preparation for cholinesterase and homogenate of the liver of rats for monoamine oxidase. Cholinesterase activity was measured according to he method described by UZSHO et al. Monoamine oxidase activity was measured according to the method described by SH0 et al. About 56% of the cholinesterase activity and about 37% of the monoamine oxidase activity were inhibited by the presence of 10-3M of PM-TC.
6. Effects on smooth muscle.
MAGNUS'S method with isolated rabbit intestine and isolated guinea pig bronchial chain was employed. At 0.01% concentration of PM-TC solution, a slight fall of tonus in the bronchial chain followed by a gradual rose was observed.At a higher concentration of more than 0.05% PM-TC solution, inhibition of peristalsis of rabbit intestine was observed.
7. Effects on blood coagulation time and red cell resistance.
Prothrombin time was determined by quick one-stage method and red cell resistance was determinedby RIBIÈRE method using blood of rabbits. No significant changes were observed on prothrombin time and red cell resistance during 1 hour following the intravenous injection of 100mg/kg of PM-TC.
8. Effects on body temperature.
Rectal temperature of rabbit was measured for a period of 1, 2 and 3 hours. No effect was observed on body temperature when 62.5mg/kg of PM-TC was administered intravenously.

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In an attempt to study the mechanism of action of minocycline and related compounds on thyroid activity, nine chemically related compounds were administered to rats.Minocycline produced a large goiter with high radioiodine uptake.Among nine compounds tested, minocycline and doxycycline were goitrogenic in rats fed a low iodine diet.Minocycline reduced thyroidal thyroxine and triiodothyronine and lowered plasma PBI, without affecting MIT/DIT. It is suggested that minocycline and related compounds produced goiter with high radioiodine uptake by blocking coupling of iodotyrosine to thyroxine and triiodothyronine.

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[in Japanese]

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A simple method for the determination of antibiotic concentration was devised using microtiter technique for serology.
According to the change indicator color of the mixture of bacterial cultures and serially dilutedsamples, reproducible results comparable to those by usingthe paper-disc method were obtained.Since the technique is applicable to very small amounts of samples, antibiotic blood levels can be determined repeatedly in the same individuals of small laboratory animals.
It is also useful for the determination of the levels of any antibiotic, in particular non-diffusible antibiotics in agar medium, as well as of the antibiogram of any bacteria.

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