Muskrats (Ondatra zibethicus) are among the most common freshwater diving mammals in North America. They have a well-developed diving response that occurs upon either forced or voluntary diving (Jones et al. 1982). This response consists of a decline in heart rate and cardiac output and a redistribution of blood flow primarily to the brain, heart and adrenal gland, with other organs being hypoperfused. Muskrats have large oxygen stores which are in the lower range of those reported for marine mammals (Snyder and Binkley, 1985). In a previous study on the metabolism of isolated muskrat and guinea pig hearts, it was shown that muskrat hearts do not pump as well as guinea pig hearts (McKean et al. 1986). This was indicated by the failure of muskrat hearts to develop a cardiac output in excess of that supplying their own coronary blood flow...

You do not currently have access to this content.