STUDIES ON THE FUNCTION OF THE UPPER URINARY TRACT
XII. Intra-renal Hemodynamics Following Temporary Occlusion of the Renal Vessels in Dog
1980 Volume 71 Issue 4 Pages 391-405
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1980 Volume 71 Issue 4 Pages 391-405
The purpose of this study was to determine if temporary occlusion of the renal vessels, which is a common surgical procedure in urologic practice, produces any ill-effect on intra-renal hemodynamics.
Twenty-one mongrel dogs weighing 13 to 30kg were used in this study. After intravenous thiamylal-Na administration, one of the kidneys was exposed extraperitoneally by a median incision in the abdomen, while the renal vessels of another kidney were ligated or nephrectomized. Enameled copper wire electrodes of 300 microns in diameter were inserted into the renal cortical and medullary tissues to the depths of 5 and 15mm from the cortical surface. The tissue PO2 was continuously measured by the Yagi's method. The changes in polarographic amplitudes following clamping of the renal vessels were expressed as percent of the pre-clamping level. The change in the cortical and medullary PO2 to 100% oxygen inhalation was also recorded. After completion of experiment, the kidneys were removed for histologic examination.
The animals were divided in to two groups according to the duration of clamping of the renal vessels: group I, 10min and group II, 60min.
The results obtained were as follows:
1) Three minutes after onset of vascular clamping of the renal vessels, the mean (±1 S. D.) tissue PO2in group I was 41.5±17.1 in the cortex and 41.7±17.7 in the medulla, while that in group II PO2 was 51.0±24.8 in the cortex and 46.8±23.6 in the medulla. Ten minutes during clamping, the cortical and medullary PO2 in group I were 30.4±17.2 and 30.0±19.8, respectively. In group II, 60min after clamping, the cortical and medullary P02 were 42.1±22.8 and 37.3±23.2, respectively.
2) In group I, 5min after the clamp was removed, the tissue PO2 rose to 78.1±11.3 in the cortex and 86.6±25.3 in the medulla. In group II, the PO2 rose to 95.1±25.5 in the cortex and 99.3±25.3 in the medulla. Thereafter, the restoration of tissue PO2 to the pre-clamping level was faster in the cortex than in the medulla, while the medullary PO2 decreased initially and then returned to the pre-clamping level.
3) The time required for tissue PO2 to restore its pre-clamping level after the clamp was removed was 75min in the cortex and 55 min in the medulla in group I, while it was 25min in the cortex and 65min in the medulla in group II. Thus, the intra-renal PO2 in both groups substantially returned to their respective preclamping levels.
4) The response time of tissue PO2 to 100% oxgen inhalation did not change significantly in the cortex before and after clamping, while it increased significantly in the medulla (p<0.05) after the clamp was removed. The response time before clamping was slightly shorter in the cortex than in the medulla.
5) Histologic study revealed some alterations in the tubular epithelium which were somewhat more intense in group I than in group II, but the glomeruli remained intact in both groups.
These findings suggest that the cortex and medulla are hemodynamically independent. It appears likely that the interruption of blood supply to the kidney, if it is within 60min, does not produce any adverse effects on renal function.
