Strychnine is rapidly absorbed into the intestines and exerts its characteristic effects on the central nervous system. The olfactory cortex, auditory cortex, somatosensory and visual cortexes are rendered more acute by stimulation of strychnine, respectively on the frontal, temporal, parietal and occipital lobes of the brain. The action of strychnine also raises epinephrine levels and thus increases systemic blood pressure by direct stimulation of the sympathetic nervous system on the smooth muscle of the arterioles. This action can be of great value in reducing cardiac failure. Many other alkaloids are found in the genus Strychnos .
Some species contain brucine, which is also found in nux vomica, chloroquine and quinine.
An experiment on a mutant Paramecium caudatum was conducted to find membrane potential responses to these alkaloids to find out similarities amongst the chemicals. The responses consisted of an initial transient depolarization when the strychnine, brucine and chloroquine concentration was low, followed by a transient hyperpolarization when the level of strychnine, brucine and chloroquine were raised. The amplitude of the responses tended to increase as the alkaloid concentration was increased but tended to saturate at high concentrations. The experiments were also concentrated on finding the various locations of receptors when exposed to the stimulus. The cells were found to produce a depolarization in response to localized applications to the anterior region, whereas the cell produced a hyperpolarization in response to the application of the posterior region.