Proceedings of the Physiological Society, 10‐11 December 1965, Zoo Meeting: Communications

Abstract

PHYSIOLOGICAL SOCIETY, 10-11 DECEMBER 1965 61P In the second method a cut film serial changer is used to make large radiographic pictures in rapid sequence.The work is developing and now also includes studies of the superior vena cava. Recordings will also be made on video tape for immediate study. FINDINGSFlow up the inferior vena cava of the rabbit is rhythmic, maximal towards the end of expiration and it slows during inspiration. At the end of inspiration, the flow may cease altogether and reflux occur into abdominal tributaries of the vena cava.The cessation of flow is due to kinking of the inferior vena cava by the descent of the diaphragm. Hepatic blood enters close to this point and has a complex effect of its own upon the general pattern.Flow through the superior vena cava is also rhythmic, but in an opposite phase, so that flow is greatest during inspiration and slowed during expiration. Thus the total return to the right atrium tends to remain constant.