Toxicants Affecting the Cardiac & Respiratory Systems I (9) Flashcards
What happens with acute toxicity of the heart?
electrical vs muscular components
What happens with chronic heart toxicity?
changes of structure of the heart itself - hypertrophy, malignant arrhythmia
What do anti-arrhythmics do to the heart?
Na+ channel block, Beta blocker, K channel block, Ca channel block
Be familiar with these I guess
What causes QT prolongation?
What is an ionophore that can kill horses?
monensin
What are ionophores?
carboxylic polyether antibiotics, isolated from streptomyces cinnamonensis, given as feed additive, coccidiostat
How do ionophores affect horses?
prolong depolarization, depolarization, ventricular tachycardia, AV block
How do ionophores affect cattle?
QT, QRS prolongation, first degree AV block, muscle damage
What are ionophore toxicities often the result of?
mixing error at the feed mill
What is amitraz?
a tri-aza-pentadiene compound used in flea collars and dogs as an insecticide and acaricide
What is the MOA for amitraz?
it exerts toxicity by inhibiting the enzyme monoamine oxidase (MAO) and works as an alpha 2 adrenergic receptor agonist - primary presynaptic
WHat are the cardiac effects of amitraz - an alpha-2 adrenergic agonist?
bradycardia, first and second degree AV block, diminished cardiac output
What is the toxicant in blister beetles?
cantharidin
What does cantharidin in blister beetles do?
inhibits serine-threonine protein phosphatase & blocks adenosine alpha-1 receptors, which regulate myocardial oxygen consumption
What are clinical signs of cantharidin toxicity from blister beetles?
tachycardia, myocardial dysfunction, colic in horses
What is characteristic of blister beetle toxicity?
thumps - diaphragmatic contractions due to hypocalcemia
What are clinical signs of bufo toad interaction and toxicity?
profuse, sometimes frothy salivation, accompanied by vigorous head shaking, pawing at the mouth, and retching
What is the toxin in bufo toads?
bufotoxin - a mix of steroid lactones that include glycosides, as well as epi, norepinephrine, and serotonin
What are clinical signs of bufotoxicity?
profuse, sometimes frothy salivation, accompanied by vigorous head shaking, pawing at the mouth, and retching
What is the toxin in foxglove digitalis spp.?
digitalis glycosides
What are the toxicokinetics in foxglove?
absorbed from the GI tract and eliminated by hepatic metabolism and in the urine
What are clinical signs of foxglove?
GI involvement including anorexia, colic, and diarrhea - often precede cardiovascular signs
What are CV signs of digitalis toxicity?
What are the toxins in milkweed?
cardenolides (similar to digitalis glycosides)
galitotoxin
What are the toxicokinetics of milkweed?
same as foxglove for cardio
neurologic not well understood
What are the toxins in oleander?
oleandrin
neriine
What is the toxic principle of oleander?
cardiac glycosides (increase the force of heart contractions and slow down the heart rate by inhibiting the Na+/K+ ATPase pump)
What part of the oleander plant is the most toxic?
red flowers
What are the toxicokinetics of oleander?
Appear to be readily absorbed from the GI tract; large dose can be fatal in 1 hour and symptoms usually appear within 24 hours
What is the mechanism of toxicity in oleander?
same as foxglove
What is the toxin in lily of the valley?
convallotoxin
What toxic principle does lily of the valley have?
cardiac glycosides
What is the toxin in azalea (rhododendron)?
grayanotoxins
What is the mechanism of toxicity in azaleas?
bind to voltage-gated Na+ channel, producing a state of depolarization
What are clinical signs of azalea toxicity? (grayanotoxins)
depression, excess salivation, bradycardia, arrhythmias, and seizures
What are the toxins in mountain laurel and sheep laurel?
grayanotoxins
What is the mechanism of toxicity for sheep and mountain laurel?
bind to voltage-gated Na+ channel, producing a state of depolarization
What are clinical signs of sheep and mountain laurel toxicity?
excessive salivation, perspiration, vomiting, dizziness, weakness & paresthesia in the extremities and around the mouth, low BP and sinus bradycardia
What is the toxin in avocado - persea Americana?
persin
What does persin in avocados cause?
myocardial necrosis in birds and mammals (horses)
What is the toxin in kalachoe species?
bufadienolides (cardiac glycosides that are similar to digitalis)
What is the mechanism of toxicity for kalanchoe species?
similar to digitalis (iinhibition of the Na+/K+ pump, primarily in intracellular Ca2+ imbalance & cardiac rhythm disturbances)
What are the toxins in dogbane (Indian hemp)?
apocynin (resin)
cymarin (cardiac glycosides)
What is the mechanism of toxicity of dogbane?
similar to digitalis (inhibition of the Na+/K+ pump, primarily in intracellular Ca2+ imbalance & cardiac rhythm disturbances)
What is the toxin in cotton / cottonseed?
gosspol
What does gossypol cause, especially when not intact?
prolonged exposure can cause acute heart failure, resulting from myocardial necrosis, renal, reproductive necrosis
What is the toxin in yew?
taxine alkaloids
What parts of the yew is toxic and nontoxic?
all parts toxic except the aril
What is using yew related to?
paclitaxel - treat cancers, extracted form bark of yew tree
