MEASUREMENT OF BLOOD-FLOW IN PANCREATIC EXCHANGE CAPILLARIES WITH FITC-LABELED ERYTHROCYTES

Characterization of pancreatic capillary blood flow by in vivo microsc opy has been limited by technical shortcomings associated with the use of plasma tracers and the lack of quantitative data. Therefore, fluor escent-labeled erythrocytes were evaluated for quantitation of pancrea tic capillary blood Row in rats in physiological state and under defin ed conditions of increased and impaired pancreatic blood Row. Physiolo gical blood Row was 1.21 +/- 0.06 nl/min per capillary with stable cap illary perfusion pattern. Reduction of pancreatic blood flow by decrea sing systemic arterial pressure to 60 mm Hg through controlled hemorrh age produced a profound decrease of volumetric flow to 0.21 +/- 0.05 n l/min (P < 0.05). The number of perfused capillaries was reduced to 52 +/- 8% of baseline (P < 0.001) and the intermittent perfusion pattern was altered in 26 +/- 5% (P < 0.001) of observed capillaries. Stimula tion of pancreatic perfusion with intravenous secretin (5 CU/kg/hr) in duced a transient decline to 0.94 nl/min (P < 0.05) followed by a cont inuous increase to 2.39 nl/min (P < 0.001). The intermittent flow patt ern was modified in 15 +/- 3% of capillaries (P < 0.05). Fluorescent-l abeled erythrocytes provide unique and reliable qualitative and quanti tative data about pancreatic microcirculatory changes. Confinement of the fluorescent tracer to erythrocytes prevents extravasation and mini mizes phototoxicity, thereby improving intravital analysis of blood Ro w in pancreatic exchange capillaries. (C) 1995 Academic Press, Inc.