| Autor: |
Stefano, A., Wittner, M., Nitschke, R., Braitsch, R., Greger, R., Bailly, C., Amiel, C., Elalouf, J., Roinel, N., Rouffignac, C. |
| Zdroj: |
Pflügers Archiv: European Journal of Physiology; 1989, Vol. 414 Issue 6, p640-646, 7p |
| Abstrakt: |
The effects of glucagon on transepithelial Na, Cl, K, Ca and Mg net fluxes were investigated in isolated perfused cortical (cTAL) and medullary (mTAL) thick ascending limbs of Henle's loop of the mouse nephron. Transepithelial ion net fluxes ( J, J, J, J, J) were determined by electron probe analysis of the collected tubular fluid. Simultaneously the transepithelial voltage (PD) and the transepithelial resistance ( R) were recorded. In cTAL-segments ( n=8), glucagon (1.2×10 mol · l) stimulated significantly the reabsorption of Na, Cl, Ca and Mg∶ J increased from 204±20 to 228±23 pmol · min · mm, J from 203±18 to 234±21 pmol · min · mm, J from 0.52±0.13 to 1.34±0.30 pmol · min · mm and J from 0.51±0.08 to 0.84±0.08 pmol · min · mm. J remained unchanged: 3.2±1.3 versus 4.0±1.9 pmol · min · mm. Neither PD (16.3±1.5 versus 15.9±1.4 mV) nor R (22.5±3.0 versus 20.3±2.6 Ωcm) were changed significantly by glucagon. However, in the post-experimental periods a significant decrease in PD and increase in R were noted. In mTAL-segments ( n=9), Mg and Ca transports were close to zero and glucagon elicited no significant effect. The reabsorptions of Na and Cl, however, were strongly stimulated: J increased from 153±17 to 226±30 pmol · min · mm and J from 151±23 to 243±30 pmol · min · mm. The rise in NaCl transport was accompanied by an increase in PD from 10.3±1.1 to 12.3±1.2 mV and a decrease in R from 19.1±2.7 to 17.8±2.0 Ωcm. No net K movement was detectable either in the absence or in the presence of glucagon. A micropuncture study carried out in hormone-deprived rats indicated that glucagon stimulates Na, Cl, K, Mg and Ca reabsorptions in the loop of Henle. In conclusion our data demonstrate that glucagon stimulates NaCl reabsorption in the mTAL segment and to a lesser extent in the cTAL segment whereas it stimulates Ca and Mg reabsorptions only in the cortical part of the thick ascending limb of the mouse nephron. These data are in good agreement with, and extend, those obtained in vivo on the rat with the hormone-deprived model. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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