Renal Pathology in the Light of Recent Neurovascular Studies

305

119

A method has been described for the measurement, by means of Kr 85 , of intrarenal nutrient blood flow distribution in the unanesthetized dog. Injection of the isotope into the renal artery is followed by a multi-exponential disappearance curve which can be obtained by external monitoring with a scintillation detector. In acute experiments autoradiographs have demonstrated that the first exponential component represents cortical blood flow; the second, outer medullary blood flow : the third, inner medullary blood flow; and the fourth, hilar and perirenal fat blood flow. The average cortical blood flow in 65 experiments in five kidneys of four nnanesthetized dogs was 472 ml/100 g/min, the outer medullary 132 ml/100 g/min, and the inner medullary 17 ml/100 g/min. Eighty per cent of the radioactivity was distributed initially to the cortex, 16% to the outer medulla, and 2% to the inner medulla. The hilar and perirenal fat, which receives approximately 2% of the initial radioactivity, was estimated to have a flow rate of 21 ml/100 g/min. In addition, a method for the rapid determination of serial cortical blood flow rates has been described. The importance of these findings has been discussed with reference to the anatomy of the kidney, and to the countercurrent concept as it applies to passive reabsorption of lipid soluble substances, and to the maintenance of an osmotic gradient.

mentioning

confidence: 75%

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Thorburn

Kopald

Herd

et al. 1963

305

119

“…• Vasoconstriction within the kidney, particularly in the outer layers of the cortex, is held to be important in the pathogenesis of acute renal failure (ARF) (1,2). Renin is stored mainly in the outer layers of the renal cortex (3,4) and, like the plasma or blood levels of renin, renin activity and angiotensin are often increased during the early stages of ARF in man (5-10) and may, by their vasoconstrictor effect, play some part in producing the condition (9, 11).…”

mentioning

confidence: 99%

Renin and Acute Circulatory Renal Failure in the Rabbit

Brown

Gavras

et al. 1972

Plasma renin concentration (PRC) was measured in 25 rabbits before and 6, 24, or 72 hours after subcutaneous injection of glycerol. Renal failure and tubular necrosis developed in most animals and PRC rose sixfold to a maximum at 24 hours. Small insignificant changes of PRC were present at 6 and 72 hours. None of these changes was observed in a control group of nine animals killed 24 hours after an injection of saline. The amount of renin extractable from single superficial glomeruli and from renal cortical tissue was reduced after injection of glycerol. In a second study of 11 anesthetized rabbits, renal venous PRC increased on average from 151 to 1810 units/liter following a 4-hour period of renal artery occlusion. Arterial PRC did not change significantly during this time, but the kidneys showed histological changes of acute tubular necrosis. These experiments are compatible with the suggestion that renin is involved in the pathogenesis of acute circulatory renal failure. KEY WORDSglomerular renin glycerol-induced renal failure acute tubular necrosis angiotensin renal artery occlusion• Vasoconstriction within the kidney, particularly in the outer layers of the cortex, is held to be important in the pathogenesis of acute renal failure (ARF) (1, 2). Renin is stored mainly in the outer layers of the renal cortex (3, 4) and, like the plasma or blood levels of renin, renin activity and angiotensin are often increased during the early stages of ARF in man (5-10) and may, by their vasoconstrictor effect, play some part in producing the condition (9, 11). However, analysis of results in man is compromised by lack of information on changes in renin in the early stages of ARF (9). In the first group of experiments reported here, therefore, plasma renin concentration was measured in rabbits before and during the development of ARF produced by glycerol.From the MRC Blood Pressure Unit and the Department of Pathology, Western Infirmary, Glasgow, W.I., Scotland.Received April 2, 1971. Accepted for publication September 27, 1971.The second question investigated was the extent to which levels of renin in peripheral plasma reflect those within the kidney under conditions, such as in ARF, in which renal blood flow is reduced. It is known, for example, that renal venous plasma renin concentration is inversely related to renal blood flow (12). In a second series of rabbits, therefore, the renal artery was occluded for a period sufficient to produce ischemic changes within the kidney, and renin was measured in samples of arterial and renal venous plasma taken before, during, and after the occlusion.A brief account of some of these results has been given recently (13). Methods A. ACUTE RENAL FAILURE PRODUCED BY GLYCEROLForty-nine rabbits were given the acidifying diet described by Lalich (14) to increase susceptibility to ARF (15), which in preliminary experiments had proved difficult to produce. Within 3 weeks, urine pH had decreased from 6.9 or more to 5.5 or less in all animals. Drinking water was then withheld, and aft...

“…Our findings may also have some bearings on the interpretation of the Trueta phenomenon-a fall in cortical flow with maintained (or possibly increased) medullary flow in response to crush lesions and shock (39). Increased activity in the sympathetic nervous system can hardly explain this observation because various authors (40)(41)(42)(43) failed to reproduce the Trueta juxtamedullary shunt pattern by infusion of epinephrine or stimulation of the renal nerves.…”

Section: Nissen Galskovmentioning

confidence: 82%

“…This view receives some support from our finding that the outer cortical flow actually is reduced to a comparatively larger degree by the microspheres. Much of the confusion (48) as to the interpretation of the findings of Trueta et al (39) may then be explained by the difficulty of reproducing the state in which aggregated blood cells (or fibrin) clog the microcirculation of the kidney in experimental animals.…”

Section: Nissen Galskovmentioning

confidence: 99%

Direct Measurement of Superficial and Deep Venous Flow in the Cat Kidney

Nissen

Galskov

1972

In an excised cat kidney, the subcapsular veins were clipped near their connections with the renal vein and cut open distal to the clamps. The kidney was then placed in an oil-filled lucite chamber and perfused from a donor cat via tubes entering the chamber through its close-fitting lid. The blood leaking from the cut subcapsular veins was led to one flowmeter; that leaving via the cannulated renal vein (supplied now only by the arcuate vein system) was led to another flowmeter. Catecholamines and stimulation of the renal nerves reduced the arcuate blood flow more than the subcapsular blood flow, the two average reductions being 28% and 20% with epinephrine and 22% and 14% with stimulation of the renal nerves. Angiotensin reduced both flows equally. Microspheres reduced the subcapsular flow more than the arcuate flow, the two average reductions being 42% and 25% of the control flows. This effect was probably caused by trapping of the microspheres in the distal ends of the interlobular arteries beyond the inlets to the afferent arterioles, since these vessels are too narrow to allow free entrance of the microspheres. The preferential effect of epinephrine and nerve stimulation on the deep circulation is thought to be the result of the special structure of the juxtamedullary glomerular units. • In the cat kidney, the veins draining the outer cortex are well separated from those draining the inner cortex and the medulla, because the blood from the outer cortex leaves through subcapsular veins which do not join the arcuate vein system until the hilar region (1, 2) (Fig. 1). In this paper, we will describe how the rates of blood flow leaving the subcapsular and the arcuate veins can be measured directly and simultaneously and show that the vessels in the two drainage areas react differently to certain external