A Definition of Proximal and Distal Tubular Compliance: PRACTICAL AND THEORETICAL IMPLICATIONS

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Abstract

Micropuncture studies were carried out in the rat to evaluate the in situ distensibility characteristics of the proximal and distal tubules under a variety of experimental conditions. In the first phase, we determined the response of tubular diameter (D) to changes in tubular pressure (P) induced by partially obstructing single tubules. The response observed under these conditions (i.e., when interstitial pressure is presumed to be constant) has been defined as the compliance of the tubule. Over the range of tubular pressures studied (10-35 mm Hg for the proximal tubule, 5-25 mm Hg for the distal tubule) the compliance characteristics of the proximal and distal tubule were found to be markedly different; the proximal tubular pressure-diameter relationship was linear, ΔD/ΔP = 0.45 μm/mm Hg, whereas the distal pressure-diameter relationship was curvilinear, ΔD/ΔP = c−0.1×P+2.2.

Authors

Stanley Cortell, F. John Gennari, Michael Davidman, William H. Bossert, William B. Schwartz, Melvin L. Ponte