ISSN:
1432-2013
Keywords:
Adrenalectomy
;
Tubuloglomerular feedback
;
Intratubular stop flow pressure
;
Loop of Henle
;
Diluting capacity
;
Renal renin content
;
Dexamethasone
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The technique of orthograde tubular microperfusion has been used to test the functional integrity of tubuloglomerular feedback control in adrenalectomized rats. Kidneys of these animals display high renin contents, as well as an impairment of electrolyte transport in the loop of Henle, which was demonstrated by monitoring the electrical conductivity of fluid entering the distal tubule over a perfusion range of 10–50 nl/min. The calculated electrolyte concentration of the perfusion fluid leaving the loop of Henle was significantly higher in adrenalectomized rats than in controls. Intratubular stop flow pressure (SFP) during perfusion with a modified “endproximal” Ringer's solution was recorded continuously in early proximal segments at rates of 0–40 nl/min. Direct pressure transmission from perfused endproximal tubular segments to the pressure recording capillary was prevented by paraffin blockade of the intermediate proximal segment. An intact feedback response in each of the 32 tubules of the adrenalectomized rats studied was observed, which was reversible and could be demonstrated repetitively in individual tubules. Thus ΔSFP at 40 nl/min was −11.2±1.3 mm Hg in adx rats as compared to −8.1±1.3 in control rats. An increased freedback sensitivity was observed in dexamethasone treated adrenalectomized rats despite normal renal renin content. Here ΔSFP at 40 nl/min was −15±1.1. Thus, the feedback signal can be mediated in the apparent absence of adrenal steroid hormones and a high sensitivity of tubuloglomerular feedback control is not necessarily paralleled by high renin content of renal tissue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584181
