Fig. 1. A sample recording of the variations in intra-abdominal pressure (IAP), central venous pressure (CVP) and total post caval vein blood flow (_PC) during ventilation (A) at rest and (B) running at 1.0 km h^–1. During expiration (Exp), IAP falls to near atmospheric pressure, and _PC increases. Peak IAP and CVP and minimum _PC occur at the end of inspiration (Insp). Inspired tidal volume was twofold higher during exercise (46.23 ml kg^–1) compared with rest (24.68 ml kg^–1). Buccal oscillations (movement of air in and out of the buccal region) occur in alligators but do not contribute to gas exchange. Data are from one alligator (mass 3.6 kg) and are representative of the trend in all alligators tested. Scale bar in A, 15 s; B, 5 s.