ISSN:
1432-2013
Keywords:
Micropuncture
;
Mg, Ca and P Excretion
;
Concentrating Mechanism
;
Loop of Henle
;
Electron Probe Analysis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Cortical and papillary micropuncture experiments were carried out on Psammomys undergoing mild hypertonic salt diuresis. Tubular fluid was collected along the proximal tubule or at the early distal tubule level, and at the tip of the longest Henle loop.3H-inulin, Na, K, Cl, Mg, Ca and P concentrations, as well as osmotic pressure, were determined in all samples. The results indicate a) no large net water movement along the loop; b) substantial addition of Na, K, Cl, Mg, and to a lesser extent Ca, along the descending limb, in proportion to the gradient; c) the tubular flow rate of phosphorus remains constant at the tip of the loop irrespective of the gradient. The constancy of the load of Na, K, Cl, Mg and Ca delivered to the distal superficial nephron, irrespective of the urinary osmotic pressure, indicates that medullary recycling between the ascending and descending limbs exists for Mg, Cl, and Ca, and confirms its existence for Na and K. In contrast, phosphorus behaves like inulin along the descending limb. A general conclusion is that in Psammomys the concentrating process along the descending limb of Henle results mainly from net addition of solutes, and not from water withdrawal.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00592784
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