Comparative cardiovascular effects of four fishery anesthetics in spinally transected rainbow trout, oncorhynchus mykiss

1. We compared the effects of four anesthetics on heart rate, dorsal and ventral aortic blood pressure, and electrocardiograms of rainbow trout (Oncorhynchus mykiss).

2. Exposure to the local anesthetics tricaine methanesulfonate (MS-222) and benzocaine hydrochloride (BZH) produced minimal cardiovascular alterations. Mean dorsal aortic pressure (DAP) decreased during exposure to MS-222, and mean DAP and mean ventral aortic pressure (VAP) increased 15% during recovery from BZH.

3. Exposure to the general anesthetic 2-phenoxyethanol (2-PE) or the hypnotic agent etomidate (ET) dramatically decreased heart rate and blood pressures and altered EKG patterns.

4. During recovery, VAP and DAP increased above baseline for an extended period. Heart rate and EKG patterns rapidly returned to normal.