Measurement of organ blood flow in the rabbit

A surgical procedure to facilitate the radioactive microsphere technique for simultaneously measuring cardiac output and its regional distribution has been developed. The procedure allows the use of either anesthetized or conscious rabbits. Organ blood flows in untreated and saline-treated conscious rabbits and saline-treated anesthetized rabbits were quantified and compared. First, comparison of data from the untreated and saline-treated conscious rabbits demonstrated a significantly lower hepatic blood flow in the untreated animals. Moreover, liver blood flow in the untreated animals was markedly less than literature values. Since the untreated rabbits were not handled on a regular basis prior to the blood flow study, it is suggested that anxiety may have caused the redistribution of splanchnic circulation. Secondly, comparison of the data from the conscious and anesthetized saline-treated rabbits demonstrated that total liver blood flow was similar and in agreement with literature values. Hence, either the conscious or anesthetized animal can be used to estimate liver blood flow. By contrast, blood flow to the kidney and caecum was significantly altered by anesthesia (propanidid: nitrous oxide: halothane), indicating that blood flow to these organs is best studied in the placid conscious rabbit.