Untersuchungen über die Wirkung von Pharmaka auf Tiere verschiedenen Alters

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Abstract
The action of Ritalin (methylphenidate) and Regitin (phentolamine) on spontaneous mobility was tested on ten 5-month-old and ten 27-31-month-old male rats. In old animals, normal mobility in control experiments with physiological NaCl solution is the first 30 minutes about half, compared with that of young animals. Ritalin 10 mg/kg, subcutaneously, increases spontaneous mobility about 3 times in the first 30 minutes in young animals. It is still high after 11/2 hours while in old animals normal mobility is reached after about 30 minutes. Regitine inhibits the increased mobility caused by Ritalin; for old animals only about 60% of the doses, which is needed for young animals, is necessary. The lethal dose of Regitine after an injection of Ritalin is smaller in old animals. In confirmation of former observations these experiments show that the central nervous excitability and also inhibition thresholds are lower in old animals than in young.