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AVP dynamically increases paracellular Na + permeability and transcellular NaCl transport in the medullary thick ascending limb of Henle's loop
Author(s) -
Leipziger Jens,
Himmerkus Nina,
Plain Allein,
Marques Rita D,
Sonntag Svenja,
Paliege Alexander,
Bleich Markus
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.703.8
Subject(s) - paracellular transport , transcellular , reabsorption , chemistry , loop of henle , water transport , endocrinology , medicine , tubular fluid , sodium , biophysics , claudin , permeability (electromagnetism) , tight junction , biology , water flow , biochemistry , membrane , organic chemistry , environmental engineering , engineering
The medullary thick ascending limb of Henle's loop (mTAL) is crucial for urine concentrating ability of the kidney. It is water tight and able to dilute the luminal fluid by active transcellular NaCl transport, fueling the counter current mechanism by increasing interstitial osmolality. While chloride is exclusively transported transcellularly, approx. 50% of sodium transport occurs via the paracellular route, driven by the lumen positive transepithelial potential. Antidiuretic hormone (AVP) is known to increase active NaCl transport to support collecting duct water reabsorption. Here we investigated the concomitant effects of AVP on the paracellular properties of mTAL. Freshly isolated mouse mTALs were perfused and electrophysiological trans‐ and paracelluar properties were assessed in a paired fashion before and after AVP stimulation. In addition the same parameters were measured in mice on a water restricted (WR) or water loaded (WL) diet for 5 days. Acute ex vivo stimulation as well as long term in vivo water restriction increased equivalent short circuit current as a measure of active transcellular NaCl transport. Intriguingly, in both experimental approaches this was accompanied by markedly increased paracellular Na + selectivity. Thus, AVP is able to acutely regulate paracellular cation selectivity in parallel to transcellular NaCl transport, allowing balanced paracellular Na + absorption under an increased transepithelial driving force.