1. GFR Measurement (Renal clearance of inulin) MUDr. Michal Jurajda Department of Patophysiology

2.  GFR glomerular filtration rate

3. Objective: Demonstration of the GFR measurement by inulin clearance test  Animal model The model of the acute renal failure caused by decreased number of glomeruli produced by ligation of the left renal artery.  Results The measurement of renal clearance of inulin. Assessment of renal function after ligation of renal artery.

4. Experimental procedure  anesthesia  laparotomy, ligation of a. renalis sinistra in experimental group,  Intravenous administration of inulin (30mg/1,5ml saline solutin) v. jugularis  cardiac puncture 5, 10, 15, 20 or 30 minute after inulin administration, withdrawal of at least 1,5 ml of coagulable blood  Spectrophotometric assay of inulin  t1/2 and C0 calculation

5. Renal clearance  The rate of removal of given substance from plasma by the kidney expressed as volume of cleared plasma per unite of time  Unit: ml/sec  GFR ? filtered solute (inulin)  Perfusion ? filtered as well as secreted solute (para-amino hippuric acid)

6. GFR tests  endogenous substances creatinin, produced by muscles from creatin cystatin C, cystein protease inhibitor  exogenous substances Inulin (starchlike polymer of fructose)

7. Creatinin  Produced in the muscles from creatin  Predominantly filtered in the kidney 90%, partially secreted 10%.  Blood levels of creatinin can be useful in evaluating renal function, but CAVE! they are not increased in early stages of renal failure  Differences between men and women due to different muscle mass

8. GFR tests  endogenous substances clearance GFR estimation  exogenous substances clearance

9. Clearance

11. Cockcroft-Gault formula  GFR ml/min  Plasma creatinine mmol/l  Men 20-80 years old (women x 0.85)

12. Exogenous substance (e.g. inulin)  Intravenous administration of a substance excreted by filtration and assay of that substance in plasma  decrease of plasma levels of that substance is exponentially related to the time  Graphical or numeric determination of half time (t1/2) and initial concentration (Co)

15. GFR calculation  D dose (g)  Co initial concentration, extrapolated  t1/2 calculated

17. Lambert-Beer law  A= cdε  A - absorbance  ε - absorbance factor  d - optical length  c - molar concentration