Figure 2.

A comparison of in vivo and in vitro maximum cardiac output and heart rate values for rainbow trout (Oncorhynchus mykiss). The in vivo values (open square symbols) were from critical swimming speed tests over a range of acclimation temperatures. The in vitro cardiac performance values (closed symbols) were from experiments with the ‘Farrell’ perfused heart preparation in which maximum performance was measured with either minimal (closed circles and solid line) or maximum (closed triangles and solid line) adrenergic stimulation over a range of acclimation temperatures. There are two important points to note from these comparisons. First, the in vitro data with maximum adrenergic stimulation are generally as good as or better than the in vivo data. Second maximum cardiac output in vitro clearly plateaus at warm temperatures, but collapses in vivo. Data sources were as follows. In vivo data: Kiceniuk & Jones 1977; Taylor et al. 1996; Thorarensen et al. 1996; Brodeur et al. 2001. In vitro data: Farrell et al. 1986, 1991, 1996; Graham & Farrell 1989; Milligan & Farrell 1991; Keen & Farrell 1994.