KINETICS OF GLUCOSE DELIVERY TO SUBCUTANEOUS TISSUE IN RATS MEASURED WITH 0.3-MM AMPEROMETRIC MICROSENSORS

The time between intravenous injection of a glucose bolus and the time the glucose concentration peaked in the subcutaneous tissue was measu red in pentobarbital-anesthetized rats with implanted 290-mu m-diamete r amperometric sensors. Boluses of 100, 200, and 400 mg/kg body wt wer e injected. The glucose concentration in the jugular vein was monitore d by frequent withdrawal and analysis of samples. The glucose concentr ation in the subcutaneous tissue was continuously monitored with the s ensors. The times required for the subcutaneously implanted sensor to reach its maximum current, corrected for sensor response times, were 7 .5 +/- 3.9, 9.8 +/- 5.5, and 10.0 +/- 4.4 min for the smallest to the largest dose, respectively. The shorter delay in response to the small est dose was statistically significant (P < 0.03). The results were co nsistent with dilution of the bolus in the cardiovascular system and t ransport of glucose by both diffusion and facilitated transport via a saturable mediator. An understanding of the differences in the dynamic s of venous vs. subcutaneous response to a glucose dose is important i n developing algorithms for the control of blood glucose based on a su bcutaneous measurement.