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Joined 2026-09-21 Message
Incoming links: Juha P. Kokko
Antonino S. Rocha 2026-11-05
Antonino S. Rocha investigated transport in the kidney, including how the thick ascending limb of the Loop of Henle handles sodium chloride and water. A 1973 study with Juha P. Kokko tested isolated rabbit nephron segments under controlled perfusion conditions.[ref]
Sodium chloride and water transport in the medullary thick ascending limb of Henle. Evidence for active chloride transport by Antonino S. Rocha and Juha P. Kokko. Byline and Abstract: isolated medullary thick ascending limbs
Increasing the surrounding osmolality produced essentially no net fluid movement in the tested segments, whereas the outgoing tubular fluid became more dilute under suitable perfusion conditions. Measurements of sodium and chloride concentrations supported removal of sodium chloride from the lumen without an accompanying large water flux.[ref]
Sodium chloride and water transport in the medullary thick ascending limb of Henle. Evidence for active chloride transport by Antonino S. Rocha and Juha P. Kokko. Abstract: imposed osmotic gradients, near-zero net fluid transport and reduced effluent ion concentrations
The illuminating result is a separation of salt and water transport. Removing dissolved material while leaving most of the water behind can dilute tubular fluid and help build a concentrating environment around the tubule. The measured transport properties are distinct from identifying every molecular transporter responsible; the paper's historical chloride-pump interpretation should not be treated as a complete modern molecular account.
Juha P. Kokko 2026-11-05
Juha P. Kokko investigated the segment-specific transport properties of the nephron. His experiments with isolated rabbit renal tubules examined how movement of sodium chloride and water contributes to the concentrating function of the kidney.[ref]
Sodium chloride and water transport in the descending limb of Henle by Juha P. Kokko. Byline and Abstract: isolated descending-limb experiments
In a 1970 study of the thin descending limb, raising the osmolality of the surrounding bath drew water out of the tubule. Concentration of the remaining fluid occurred mainly through water loss rather than substantial entry of sodium chloride. The preparation showed relatively high water permeability and low sodium permeability under the tested conditions.[ref]
Sodium chloride and water transport in the descending limb of Henle by Juha P. Kokko. Abstract: hyperosmotic bath, measured permeability and water-efflux interpretation
A later study with Antonino S. Rocha demonstrated a different combination in the thick ascending limb: salt removal with very little net water movement. Comparing the two segments makes their complementary functions clearer than describing the entire Loop of Henle as having one permeability.[ref]
For example, concentrating a solution by removing water and diluting it by removing sodium chloride are different operations. Distinct neighboring segments can perform these operations within the same nephron.