Assessment of renal hemodynamic factors in whole kidney glomerulotubular balance

Daugharty, TM; Zweig, S. M.; Earley, Laurence E.

doi:10.1152/ajplegacy.1971.220.6.2021

Cited by 6 publications

(9 citation statements)

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“…There has not been general agreement in the experimental literature on the extent to which variations in peritubular capillary plasma flow rate alter the rate of reabsorption by the proximal tubule. Brenner and co-workers (11,12,14,15) have generally found little flow dependence, while the findings of Lewy and Windhager (29), Daugharty et al (30), and Schrier and Humphreys (31) indicate that, at least under certain conditions, variations in plasma flow may have significant effects on reabsorption. Fig.…”

Section: Discussionmentioning

confidence: 98%

A Model of Peritubular Capillary Control of Isotonic Fluid Reabsorption by the Renal Proximal Tubule

Deen¹,

Robertson²,

Brenner³

1973

Biophysical Journal

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A mathematical model of peritubular transcapillary fluid exchange has been developed to investigate the role of the peritubular environment in the regulation of net isotonic fluid transport across the mammalian renal proximal tubule. The model, derived from conservation of mass and the Starling transcapillary driving forces, has been used to examine the quantitative effects on proximal reabsorption of changes in efferent arteriolar protein concentration and plasma flow rate. Under normal physiological conditions, relatively small perturbations in protein concentration are predicted to influence reabsorption more than even large variations in plasma flow, a prediction in close accord with recent experimental observations in the rat and dog. Changes either in protein concentration or plasma flow have their most pronounced effects when the opposing transcapillary hydrostatic and osmotic pressure differences are closest to equilibrium. Comparison of these theoretical results with variations in reabsorption observed in micropuncture studies makes it possible to place upper and lower bounds on the difference between interstitial oncotic and hydrostatic pressures in the renal cortex of the rat.

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Section: Discussionmentioning

confidence: 98%

A Model of Peritubular Capillary Control of Isotonic Fluid Reabsorption by the Renal Proximal Tubule

Deen¹,

Robertson²,

Brenner³

1973

Biophysical Journal

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“…The degree of balance between intraluminal load and reabsorption was not as complete in this study as is the degree of glomerulotubular balance during a reduction in renal perfusion pressure (23). It may be that intraluminal factors operate together with peritubular factors (14)(15)(16)(17)(18)(19)(20)(24)(25)(26) to effect an optimal degree of coupling between load and reabsorption. Also, peritubular and other factors may determine a level of reabsorption on which background intraluminal factors operate to maintain relatively constant fractional reabsorption when filtration rate changes.…”

Section: Details Of This Experiments Are Given Inmentioning

confidence: 99%

Effect of Intraluminal Flow on Proximal Tubular Reabsorption

Bartoli¹,

Conger²,

Earley³

1973

J. Clin. Invest.

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A B S T R A C T Micropuncture techniques in the rat were used to reinvestigate the possibility that intraluminal flow rate per se may influence net volume reabsorption by the proximal tubule. An experimental design was devised which lowered intraluminal flow without affecting filtration rate of the nephron under study or without directly affecting other renal hemodynamics. In 11 rats flow of tubular fluid between early and late proximal tubular sites was reduced by partially collecting tubular fluid at the early puncture site. In 42 nephrons the rate of flow of tubular fluid was reduced an average of 45% without changing nephron filtration rate and there was an associated reduction in reabsorption between the two sites which averaged 29%. This indicated 63% balance between delivery of tubular fluid and the rate of reabsorption between two sites along proximal tubules. The results of these studies indicate that a reduction in delivery of normal filtrate along the proximal tubule is associated with a concordant reduction in the absolute rate of reabsorption. Since this relationship occurred in the absence of changes in renal hemodynamics or even a change in filtration rate of the nephron under study it is concluded that changes in intraluminal load per se play an important role in the phenomenon of glomerulotubular balance.

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“…Additional evidence in support of this concept has been reviewed elsewhere (38,44). Interestingly, in all of the published studies in which strong plasma flow dependence of APR has been observed (46)(47)(48), the experimental conditions favored equilibrium. Lewy and Windhager (46) found strong flow dependence of reabsorption during partial renal venous occlusion; P o was measured to be at least twice normal and therefore approached ir 0 more closely than normal.…”

Section: Renal Transcapillary Fluid Exchangementioning

confidence: 84%

“…Although not measured, P c would likewise have been expected to be elevated in the studies by Daugharty et al (47) and Schrier and Humphreys (48). The recent findings by Ott et al (41) suggest that P h estimated using implanted capsules, increases to a lesser extent than does Pc for a variety of conditions similar to those in the studies just cited (46)(47)(48). Therefore, in the studies exhibiting strong flow dependence of APR (46)(47)(48) it seems likely that elevations in P c would have favored a closer approach to equilibrium than normal.…”

Section: Renal Transcapillary Fluid Exchangementioning

confidence: 90%

“…Thus, by experimental design, these studies were such as to favor strong plasma flow dependence of APR as in curve 4 of Figure 3. Unfortunately, it is impossible to offer estimates of the interstitial pressures in these studies (46)(47)(48), because a number of the quantities needed as inputs for the peritubular absorption model (36) were not measured.…”

Section: Renal Transcapillary Fluid Exchangementioning

confidence: 99%

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