Structure Function Correlation on Rat Kidney

Over the past few decades an exceedingly large number of experimental and clinical investigations have been performed in an attempt to analyze the way in which the kidney functions. The basis for all this work was established during the nineteenth and the early twentieth century by morphologists (Bowman 1842; Hyrtl1863, 1872; Heidenhain 1874; Peter 1909; von Mollendorf 1930). All these investigators clearly outlined the extremely heterogeneous assembly of renal tissue and also defined the nephron as the smallest morphological unit. It was further the merit of these anato­ mists and histologists to preclude quite a number of nephron functions based merely on their careful observations. Contemporary histologists have been able to add little to these observations. Unfortunately with the introduction of physiologic in vivo et situ studies on kidneys the interest in heterogeneity waned. This lack of attention was aggravated by the introduction of the clearance techniques which cannot account for regional differences in the function of the smallest unit, the nephron. That ana­ tomic heterogeneity has a functional correlate was strongly suggested by Trueta et al. (1947) and vigorously stimulated a number of studies. The development of physiologic microtechniques, like micropuncture and microperfusion of single nephrons, or the perfusion of isolated nephron portions and electrophysiologic studies, enormously expanded our knowledge concerning details regarding nephron and total renal func­ tion.

1 Introduction.- 2 Organization of the Rat Kidney.- 2.1 Cortex.- 2.2 Outer Zone of Renal Medulla.- 2.3 Inner Zone of Renal Medulla.- 2.4 Nephron Structure.- 2.4.1 Proximal Tubule.- 2.4.2 Thin Limb of Henle’s Loop.- 2.4.3 Distal Nephron.- 2.4.4 Collecting Duct.- 3 Basic Principles of Stereology.- 3.1 Structural Parameters and Profiles on Sections.- 3.2 Methods of Estimating Volume Densities.- 3.3 Estimation of Surfaces.- 3.4 Estimation of Length.- 4 Material and Methods.- 4.1 Stereological Analysis.- 4.1.1 Animal Preparation.- 4.1.2 Sampling of the Normal Rat Kidney for Stereology.- 4.1.3 Specimen Preparation.- 4.1.4 Stereological Analysis.- 4.1.4.1 Light Optimal Level (Cortex and Outer Stripe of Outer Medulla).- 4.1.4.2 Low Electron Microscopic Magnification.- 4.1.5 Stereological Analysis of the Injured Rat Kidney.- 4.2 Determination of Size of Reference Volumes.- 4.3 Biochemical Investigations.- 4.3.1 Marker Enzymes.- 4.3.2 Metabolites.- 4.3.3 Mercury and Calcium Accumulation.- 4.4 Physiologic Parameters.- 4.4.1 Glomerular Filtration Rate (GFR).- 4.4.2 Measurement of Mitochondrial Respiration.- 5 Results.- 5.1 Quantitative Morphology of the Normal Rat Kidney.- 5.1.1 Relative Values.- 5.1.1.1 Proximal Tubule: S1 + S2 Segments.- 5.1.1.2 Proximal Straight Tubule: S3 Segment.- 5.1.1.3 Thin Limb of Henle’s Loop.- 5.1.1.4 Distal Tubule.- 5.1.1.5 Collecting Duct.- 5.1.2 Subcellular Parameters Per Unit Length of Nephron.- 5.1.2.1 Proximal Nephron.- 5.1.2.2 Thin Limb.- 5.1.2.3 Distal Nephron.- 5.1.2.4 Collecting Duct.- 5.1.3 Absolute Values.- 5.2 Quantitative Morphology of the Acutely Injured Kidney Cortex.- 5.2.1 The HgC12 Model.- 5.2.1.1 Qualitative Morphology.- 5.2.1.2 Quantitative Morphology.- 5.2.2 The HgC12 Model; Six Hours After a Single HgC12 Dose and Counterheating.- 5.2.2.1 Qualitative Morphology.- 5.2.2.2 Quantitative Morphology.- 5.2.3 The Maleic Acid Model.- 5.2.3.1 Qualitative Morphology.- 5.2.3.2 Quantitative Morphology.- 5.2.4 The Ischemic Model ― No Blood Reflow.- 5.2.4.1 Qualitative Morphology.- 5.2.4.2 Quantitative Morphology.- 5.2.5 The Ischemic Model ― Blood Reflow for Forty-five Minutes.- 5.2.5.1 Qualitative Morphology.- 5.2.5.2 Quantitative Morphology.- 5.2.6 The Hypothermia Model.- 5.2.6.1 Qualitative Morphology.- 5.2.6.2 Quantitative Morphology.- 5.3 Functional Changes of the Acutely Injured Kidney Cortex.- 5.3.1 Enzyme Activities.- 5.3.1.1 The Plasma Membrane.- 5.3.1.2 The Mitochondrial Cristae Membrane System.- 5.3.2 Mitochondrial Respiration.- 5.3.3 Metabolite Concentrations.- 5.3.4 Renal Functional Parameters During Acute Injury.- 5.3.4.1 The HgC12 Model.- 5.3.4.2 The Maleic Acid Model.- 5.3.4.3 The Ischemic Model.- 5.3.4.4 The Hypothermia Model.- 6 Discussion.- 6.1 The Normal Kidney.- 6.1.1 Proximal Nephron.- 6.1.1.1 Cortex.- 6.1.1.2 Outer Stripe of Outer Medulla.- 6.1.2 Thin Limb.- 6.1.2.1 Inner Stripe of Outer Medulla.- 6.1.2.2 Inner Medulla.- 6.1.3 Distal Nephron.- 6.1.3.1 Inner Stripe of Outer Medulla.- 6.1.3.2 Outer Stripe of Outer Medulla.- 6.1.3.3 Cortex.- 6.1.4 Collecting Duct System.- 6.1.5 Absolute Values.- 6.2 The Acutely Injured Kidney Cortex.- 6.2.1 The HgC12 Model.- 6.2.2 The Maleic Acid Model.- 6.2.3 The Ischemic Model Without Blood Reflow.- 6.2.4 Ischemia with Blood Reflow.- 6.2.5 The Hypothermia Model.- 6.2.6 The HgC12 Model ― Six Hours After HgC12 and Counterheating.- 7 Summary.- References.