Glucose Perturbation in Experimental Hyperviscosity

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Abstract
Summary: Hyperviscosity was produced in one member of each of 7 sets of twin newborn lambs by an exchange transfusion with 500 ml maternal packed red blood cells. The remaining seven control twin lambs underwent an identical exchange with maternal whole blood. Postexchange hematocrits were 63 ± 6 and 29.0 ± 3% (mean ± S.E.), respectively (P ≤0.01). Whole blood viscosity measured at 3 rpm increased from 3.2 ± 0.4 centipoise (cps) to 14.4 ±6.1 cps in the lambs made hyperviscous (P ≤0.01) and remained unchanged in the control lambs (2.2 ± 0.2 versus 2.8 ± 0.3 cps). A 2-hr steady state glucose infusion was performed on each lamb before and after the packed cell or whole blood exchange transfusion. Mean steady state plasma glucose concentrations were significantly decreased from pre-exchange steady state glucose infusion levels in the same lambs made hyperviscous (P ≤0.05), whereas steady state glucose levels increased from pre-exchange levels in the twin lambs exchanged with maternal whole blood. Mean plasma insulin and glucagon values for the hyperviscous and control lambs remained unchanged during the glucose infusion. Speculation: The fmding of an abnormality in glucose homeostasis in the absence of a hormonal or substrate disturbance in hyperviscous lambs suggests that there may be rapid glucose utilization from increased cerebral extraction of glucose and/or a reduction in endogenous glucose production caused by sluggish hepatic circulation.