Ca2+, Mg2+ and K+ transport in the cortical and medullary thick ascending limb of the rat nephron: influence of transepithelial voltage.

Isolated segments of rat cortical (cTAL) and medullary (mTAL) thick ascending limbs were microperfused and the transepithelial net fluxes (JX) were determined by measuring the composition of the collected fluid with an electron microprobe. When perfused with symmetrical solutions both segments showed similar JNa and JCl and lumen-positive transepithelial voltage (Vte = 7-8 mV). JMg, JCa and JK were not significantly different from zero.

Insulin stimulates Na+, Cl-, Ca2+, and Mg2+ transports in TAL of mouse nephron: cross-potentiation with AVP.

Insulin (Ins) decreases Na+ delivery in the final urine. To determine whether the loop of Henle participates in this reduction, the effects of Ins were tested on cortical (CTAL) and medullary thick ascending limbs (MTAL) of the mouse nephron, microperfused in vitro. In the MTAL, Ins increased the transepithelial potential difference (Vt) and the Na+ and Cl- net reabsorption fluxes (JNa and JCl, respectively) in a dose-dependent manner, the threshold being below 10(-9) M.

Transepithelial Ca2+ and Mg2+ transport in the cortical thick ascending limb of Henle's loop of the mouse is a voltage-dependent process.

The mechanisms responsible for transepithelial Ca2+ and Mg2+ in transport in the isolated perfused cortical thick ascending limb (cTAL) of Henle's loop of the mouse nephron were investigated by measuring transepithelial voltages (PDte) and transepithelial ion net fluxes (JNa, JCl, JK, JCa, JMg) by electron microprobe analysis. In the presence of furosemide (10(-4) mol.l-1, lumen) and diphenylamine-2-carboxylate (DPC, 10(-4) mol.

Hormonal stimulation of Ca2+ and Mg2+ transport in the cortical thick ascending limb of Henle's loop of the mouse: evidence for a change in the paracellular pathway permeability.

Recent studies from our laboratory have shown that in the cortical thick ascending limb of Henle's loop of the mouse (cTAL) Ca2+ and Mg2+ are reabsorbed passively, via the paracellular shunt pathway. In the present study, cellular mechanisms responsible for the hormone-stimulated Ca2+ and Mg2+ transport were investigated. Transepithelial voltages (PDte) and transepithelial ion net fluxes (JNa, JCl, JK, JCa, JMg) were measured in isolated perfused mouse cTAL segments.

Effects of calcitonin on function of intercalated cells of rat cortical collecting duct.

In the rat cortical collecting duct (CCD), the presence of highly specific receptors to calcitonin (CT) coupled to a sensitive adenylate cyclase system suggests that this segment is a target site for CT. Our aim was to explore the effects of CT on the rat CCD microperfused in vitro. The hormone failed to alter the osmotic water permeability and did not affect net Na+ transport but generated a lumen-positive transepithelial potential difference (PDte), which under control conditions was close to zero.