Fig. 2. Effects of increasing output pressure (power curves) of the systemic (A,B) or pulmonary (C,D) outflows on central flows (A,C) and power output (B,D) of the in situ perfused Python molurus heart. In each case, output pressure of the other circulatory system was maintained at a constant level. All values are means ± S.E.M. (N=7); an asterisk indicates significant differences (P<0.05) between systemic or pulmonary flows and power outputs at a given outflow pressure. NS, not significantly different; sys, systemic; pul, pulmonary; tot, total.