Splenic blood flow and intrasplenic flow distribution in rats

Summary In 75 rats, anesthetized with pentobarbital and breathing spontaneously, regional splenic blood flow (rSBF) was measured by means of the⁸⁵Kr(β)-clearance technique after an intraaortic slug injection of the dissolved indicator. In the normal and undisturbed spleen in situ rSBF is linearly related to the mean arterial blood pressure (MABP) within the range of 30–140 mm Hg. Mean rSBF is 0.71 ml/g/min, the mean arterial blood pressure being 105 mm Hg. In normal rats rSBF decreases significantly with increasing body weight or age. After total obstruction of the open circulation by application of rigid spherocytes, mean rSBF is reduced to 0.26 ml/g/min and is independent of the mean arterial blood pressure within the same range. In splenomegaly, due to enhanced reticuloendothelial activity and intensified immunological responses after tumor implantation, an increase in total splenic blood flow is found. However, related to 1 g of splenic wet weight, rSBF is diminished. In splenomegaly, rSBF also linearly depends on MABP within a wide range. Mean rSBF is 0.51 ml/g/min, the mean arterial blood pressure being 91 mm Hg. The distribution of intrasplenic blood flow between open and closed circulation depends on the size of the mean arterial blood pressure. The perfusion rate of the open circulation, compared with rSBF amounts to 72–93% (MABP=80–130 mm Hg).