Cardiorespiratory effects of brevetoxin (PbTx-2) in conscious, tethered rats.

The cardiorespiratory effects of various doses of brevetoxin (0-100 micrograms PbTx-2/kg) were studied in conscious, tethered rats, After surgical preparation and a 24 hr recovery, toxin or vehicle was infused into the tethered, awake rats for 1 hr. They were then monitored for 6 hr or until death. Toxin-infused rats had decreased core and peripheral temperatures and decreased respiratory rates; these values were all low in the 100 micrograms/kg group at the time of death. Blood gas values remained within normal limits, except terminally. Electrocardiographic (ECG) disturbances, noted in all groups given greater than or equal to 25 micrograms/kg, included heart block, premature ventricular contractions and idioventricular rhythms. It was concluded that brevetoxin causes changes in cardiac conduction and multiple changes in nervous system function.