INTERMITTENCE OF BLOOD-FLOW IN LIVER SINUSOIDS, STUDIED BY HIGH-RESOLUTION IN-VIVO MICROSCOPY

Kupffer cell migration and leukocyte-vessel wall interactions cause te mporary slowing and/or stoppage of blood flow through individual liver sinusoids. Such temporal heterogeneity of flow was quantified in anes thetized mice and rats. Video recordings of red blood cell flow in 44 networks containing 8-16 sinusoids each were analyzed for 5- to 10-min periods. Flow was graded ''fast,'' ''slow,'' ''stopped,'' or ''revers ed'' based on red blood cell velocity. The mean numbers of flow change s (between grades) per minute in zone 1 vs. zone 3 were 1.39 vs. 0.78 (mouse) and 1.25 vs. 0.09 (rat). The mean percentage of time for each flow grade differed significantly between zones 1 and 3 and between sp ecies. For example, fast flow was present in zone 1 sinusoids for 51% of the time in mice and for 74% in rats; in zone 3 the corresponding n umbers were 76 and 95%. Flow stasis was present in zone 1 sinusoids fo r 19% of the time in mice and for 7% in rats; in zone 3 the correspond ing numbers were 2 and 0%. Thus considerable intermittence of perfusio n exists, and the flow conditions create very different microenvironme nts for hepatocytes in zone 1 vs. zone 3.