THE MEASUREMENT OF LIVER BLOOD FLOW IN CONSCIOUS CALVES

¹ Agricultural and Food Research Council Institute of Animal Physiology, Babraham, Cambridge CB2 4AT

Observations were made following single I.V. injections or during continuous I.V. infusions of sulphobromophthalein (BSP) in three Jersey calves (3-5 months of age) which had an indwelling hepatic vein catheter, surgically implanted under general anaesthesia. Simultaneous sampling of blood from a peripheral (jugular) vein and an hepatic vein enabled calculations of hepatic plasma flow (E.H.P.F.) based on the Fick principle. Estimates of E.H.P.F. in nine single injection experiments gave a mean flow of 38·6 ml.min^-1. kg^-1 compared to 32·6 ml.min^-1 kg^-1 estimated in seven continuous infusion experiments. The over-all mean haematocrit in the three calves was 30·0% and the E.H.P.F. values are equivalent to hepatic blood flows of 55 and 47 ml.min^-1. kg^-1 respectively. In thirteen out of fourteen experiments the plasma clearance of BSP in jugular vein blood after a single i.v. injection of 5 mg BSP.kg^-1 body weight was best fitted by a double exponential model of distribution of BSP. Parameters from these exponentials were used to calculate E.H.P.F. by the method of Clarkson, Hardy-Smith & Richards (1976) and gave values of 11·3 ml.min^-1. kg^-1, clearly indicating that the method cannot be applied in conscious calves.