MARINE TOXINS AND VENOMOUS AND POISONOUS MARINE ANIMALS
317
hypotension (Banner et al., 1963a). I n cats, similar changes have been
observed by us following administration of the toxin. In small doses
the poison produces a fall in systemic arterial pressure concomitant
with an increase in respiratory rate, and transient changes in the
electrocardiogram and electroencephalogram. With large doses there is
a more precipitous fall in systemic arterial pressure and severe respiratory distress, which may sometimes lead to cessation of respirations.
The electrocardiogram may reflect changes varying from prolongation
of the PR interval or ST, T segment changes to a third degree block.
The changes in the electroencephalogram are indicative of a decreased
blood supply to the brain. The toxin did not appear to have a direct,
deleterious effect on those areas of the brain where the conventional
lead electrodes were placed.
Further studies by Banner and his colleagues (1963b) indicated that
the toxin appeared to have an effect on mammalian neuromuscular
transmission, or a t least on the junction and/or the nerve. Direct
stimulation of the muscle produced contractions which were not
significantly altered by the toxin. I n the toad sciatic nerve-sartorius
muscle preparation these investigators found that the normal twitch
and tetanus response elicited through the nerve were lost following
prolonged exposure to the toxin ; the muscle retained its contractility
when stimulated directly. Observations from a single experiment
performed in our own laboratory appeared to indicate that the toxin
had a direct effect on the post-synaptic membrane, similar to that of
certain non-depolarizing, blocking substances. It has not yet been
possible to evaluate this single observation.
Mammals which ingest fish containing the ciguatera poison develop
muscular weakness, particularly in the hind legs first, muscular incoordination and ataxia, vomiting, diarrhea, and increased parasympathetic activity. If lethal amounts are consumed, marked
respiratory distress, vomiting, salivation, cyanosis and prostration
are often seen prior to death. Deep reflexes are usually hypoactive,
and in the more severe cases of poisoning the animal loses its righting
reflex.
(c) Clinical problem. I n 1871, Garnier wrote that in New Caledonia
fish poisoning occurred so frequently that " some apprehensive people
no longer dare to eat fish ". " The islanders attribute these illnesses to
evil spirits who will conceal themselves in the bodies of fish to torment
them." According to Banner et al. (19634, replies from questionnaires
sent out by the South Pacific Commission indicated that fish poisoning
was known in practically every island in the region. The number of
317
hypotension (Banner et al., 1963a). I n cats, similar changes have been
observed by us following administration of the toxin. In small doses
the poison produces a fall in systemic arterial pressure concomitant
with an increase in respiratory rate, and transient changes in the
electrocardiogram and electroencephalogram. With large doses there is
a more precipitous fall in systemic arterial pressure and severe respiratory distress, which may sometimes lead to cessation of respirations.
The electrocardiogram may reflect changes varying from prolongation
of the PR interval or ST, T segment changes to a third degree block.
The changes in the electroencephalogram are indicative of a decreased
blood supply to the brain. The toxin did not appear to have a direct,
deleterious effect on those areas of the brain where the conventional
lead electrodes were placed.
Further studies by Banner and his colleagues (1963b) indicated that
the toxin appeared to have an effect on mammalian neuromuscular
transmission, or a t least on the junction and/or the nerve. Direct
stimulation of the muscle produced contractions which were not
significantly altered by the toxin. I n the toad sciatic nerve-sartorius
muscle preparation these investigators found that the normal twitch
and tetanus response elicited through the nerve were lost following
prolonged exposure to the toxin ; the muscle retained its contractility
when stimulated directly. Observations from a single experiment
performed in our own laboratory appeared to indicate that the toxin
had a direct effect on the post-synaptic membrane, similar to that of
certain non-depolarizing, blocking substances. It has not yet been
possible to evaluate this single observation.
Mammals which ingest fish containing the ciguatera poison develop
muscular weakness, particularly in the hind legs first, muscular incoordination and ataxia, vomiting, diarrhea, and increased parasympathetic activity. If lethal amounts are consumed, marked
respiratory distress, vomiting, salivation, cyanosis and prostration
are often seen prior to death. Deep reflexes are usually hypoactive,
and in the more severe cases of poisoning the animal loses its righting
reflex.
(c) Clinical problem. I n 1871, Garnier wrote that in New Caledonia
fish poisoning occurred so frequently that " some apprehensive people
no longer dare to eat fish ". " The islanders attribute these illnesses to
evil spirits who will conceal themselves in the bodies of fish to torment
them." According to Banner et al. (19634, replies from questionnaires
sent out by the South Pacific Commission indicated that fish poisoning
was known in practically every island in the region. The number of