The maximal removal rate of indocyanine green (ICG Rmax) is considered to be an important parameter of hepatic function. However, the method of analysis has some flaws, and an abnormal value is obtained for about 15% of patients. We developed a new method of measuring the ICG Rmax with a clearance meter (RK-1000) that continuously measured the ICG concentration using a fingertip optical sensor. Twenty patients were examined. The histologic diagnosis was as follows: normal for 10, cirrhosis in 6, hepatitis in 4. The ICG concentration was measured in vivo continuously with the RK-1000. To obtain the Rmax by the Michaelis-Menten model, the ICG concentration in the VLDL compartment was subtracted from the values obtained by the RK-1000 because ICG binds to various serum proteins and its rate of removal in the VLDL compartment differs from that in other protein compartments. The removal velocity was calculated and a Michaelis plot obtained. Then Rmax was calculated from the reciprocal of the y-intercept of a Lineweaver-Burk plot. The Rmax in subjects with liver disease was significantly lower than in those with normal liver. It is concluded that our new method of measuring ICG Rmax with the RK-1000 reflects liver function appropriately.
Six male long‐distance runners performed knee flexion exercises in a 2.1 T superconducting magnet. 31P MRS was used to investigate the splitting pattern of the inorganic phosphate (Pi) peak during active and passive recovery. During exercise splitting of the Pi peak into two was observed (high and low pH) and after exercise the manner in which the Pi peak disappeared was different in passive and active recoveries. During passive recovery, in which exercise was not performed at all, the high‐pH Pi peak disappeared more rapidly than the low‐pH Pi peak. The low‐pH Pi peak remained at a similar acidified chemical shift as during exercise, and then gradually disappeared during passive recovery. Conversely, during active recovery in which unloaded exercise was followed, the high‐pH Pi peak was reduced, but remained, whereas the low‐pH Pi peak returned very quickly to the pre‐exercise level and then disappeared. The recovery rate of the low pH during active recovery (0.095±0.019 pH units/min) was significantly faster than that during passive recovery (0.014±0.019 pH units/min) (p<0.01). The slow disappearance of the low pH Pi peak during passive recovery can be explained by the halting of glycogenolysis and an insufficient oxygen supply to resting glycolytic fibers, whereas the quick disappearance observed with active recovery would have been due to elevated sufficient oxygen supply and efficient removal of lactate as a result of the maintained blood flow. Oxy‐myoglobin and hemoglobin was also measured with near infrared spectroscopy.
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