STUDIES ON VERATRUM ALKALOIDS. XXXVI. THE ACTION OF GERMINE MONOACETATE AND GERMINE DIACETATE ON MAMMALIAN SKELETAL MUSCLE

¹ Department of Pharmacology, Harvard Medical School, Boston, Massachusetts

Germine monoacetate (GMA) and germine diacetate (GDA) were found to increase the mechanical response to a single stimulation (twitch tension) in the gastrocnemius-soleus and in the tibialis anterior muscle of the cat. The effect occurred in the presence of different anesthetic agents. The increase in twitch tension occurred without any change in the magnitude of tetanic tension.

The effect could be demonstrated in muscles which had been denervated 7 to 14 days previously, and it was not suppressed by doses of neuromuscular blocking agents which completely interrupted impulse transmission from nerve to muscle.

The single action potential, which is elicited in response to a single stimulus in normal muscles, was converted into a short burst of repetitive action potentials after administration of effective doses of GMA and GDA. Four or 5 supramaximal stimuli, administered at rates between 50/second and 200/second, produced tension of a magnitude comparable to the tension produced after a single stimulation in the presence of the germine esters.

The magnitude of the tension developed in response to a series of stimuli, administered at rates which produced maximal tetanic tension (between 50 and 200/second), was related to the total number of stimuli given, not to the duration of time from the first to the last stimulation.