EFFECTS OF ENDOTOXIN ON MICRO-VASCULAR FLOW VELOCITY AND INDICATOR DISPERSION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 7  (4) , 387-398
Abstract
The effects of [bacterial] endotoxin (3 mg/kg LD100) on the microcirculation of exposed mesentery were studied in anesthetized cats (0.7 kg). A femoral artery and vein were cannulated for arterial pressure determination and injections. Successive bolus injections (0.05 ml) of blood containing sulfhemoglobin red blood cells (SH-RBC) and fluorescein isothiocyanate-labeled dextran (FITC-Dextran) were made into a mesenteric artery branch. The indicator passage through the microvessels was recorded on videotape. Upon replay, the outputs of an injection signal and 2 video sampler (VS) intensity-sensitive windows (placed at each end of the vessel) were monitored for obtaining indicator time-concentration curves. The arteriolar flow velocity was calculated as the distance between windows (mm) divided by the difference in mean transit time (.hivin.t) of the 2 curves. Vessel dimensions were determined as the calibrated distance between the windows. During the 1st h postendotoxin, the arterial pressure decreased while arterioles (35 .mu.m and larger) and venular diameters increased. Terminal arteriole (20-.mu.m) diameters decreased. SH-RBC and FITC-Dextran velocities decreased 50%, .hivin.t increased and indicator dispersion increased. Arterial pressure increased to above control levels during the next 2 h and 55-.mu.m and 35-.mu.m arteriolar and venular diameters decreased and 20 .mu.m arterioles increased; SH-RBC and FITC-Dextran flow velocities gradually decreased; arteriolar .hivin.t increased markedly; and indicator dispersion increased. During the terminal phase, arterial pressure decreased rapidly, all vessel diameters increased, velocities decreased, .hivin.t markedly increased and indicator dispersion increased. Control SH-RBC velocities were greater and .hivin.t were less than for FITC-Dextran.