Fig. 1. A representative recording from one varanid lizard (post exercise) demonstrating that costal ventilation caused phasic alterations in post caval blood flow (_PC) and intra-abdominal pressure (P_IA). A 25.0 ml expiration increased _PC by 6.91 ml min^-1 and P_IA by 2.21 mmHg. A 23.3 ml inspiration decreased _PC by 3.61 ml min^-1 and P_IA by 2.97 mmHg. The effect of respiratory cycle variations in P_IA was a net increase in _PC, comparable to the respiratory pump in mammals. Note: _PC blood flow was pulsatile with a rate that was strongly correlated with heart rate. Gular pumps (^*) decrease P_IA slightly, but do not alter _PC beyond fluctuations due to heart rate variability. Trace taken 10 min after exercise at 30°C in V. exanthematicus (mass 502 g). Scale bar, 15 s. 1 mmHg=133.3 Pa.