Objective—To compare the effects of the ergot alkaloid
ergovaline with effects of ergotamine on blood
pressure, heart rate, respiratory rate, and body temperature
in conscious sheep.
Animals—3 sheep with indwelling arterial catheters.
Procedure—Ergotamine and ergovaline were injected
IV (20 nmol/kg), and their effects on arterial blood
pressure, heart rate, respiratory rate and pattern,
body temperature, and skeletal muscle electromyographic
activity were compared with control values
obtained following injections of saline (0.9% NaCl)
solution or acetone.
Results—Both ergopeptides caused immediate and
significant increases in blood pressure (50 to 75 mm
Hg) without concomitant increases in heart rate.
Ergovaline but not ergotamine significantly increased
pulse pressure (35 mm Hg). Both ergopeptides resulted
in decreased respiratory rate and increased respiratory
depth within the first hour of administration.
Body temperature was decreased slightly upon
ergopeptide administration but continued to increase
thereafter, with greater increases developing with
ergovaline than with ergotamine. Increased body
temperatures of 3.0 to 3.5 C were maintained for at
least 10 hours. Respiratory rate was increased to
rates as high as 210 to 220 breaths/min in association
with hyperthermia. Ergopeptides had no effect on
skeletal muscle electromyographic activity.
Conclusions and Clinical Relevance—In sheep,
ergovaline has similar effects to ergotamine on cardiovascular
and pulmonary function and body temperature
but is more potent. These effects are consistent
with clinical signs observed in the toxicoses
developed when ruminants ingest grass with high
concentrations of ergopeptides. (Am J Vet Res