Effects of glucagon on Na+, Cl-, K+, Mg2+ and Ca2+ transports in cortical and medullary thick ascending limbs of mouse kidney.
The effects of glucagon on transepithelial Na+, Cl-, K+, Ca2+ and Mg2+ 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 (JNa+, JCl-, JK+, JCa2+, JMg2+) were determined by electron probe analysis of the collected tubular fluid. Simultaneously the transepithelial voltage (PDte) and the transepithelial resistance (Rte) were recorded. In cTAL-segments (n = 8), glucagon (1.2 x 10(-8) mol.1-1) stimulated significantly the reabsorption of Na+, Cl-, Ca2+ and Mg2+: JNa+ increased from 204 +/- 20 to 228 +/- 23 pmol.min-1.mm-1, JCl- from 203 +/- 18 to 234 +/- 21 pmol.min-1.mm-1, JCa2+ from 0.52 +/- 0.13 to 1.34 +/- 0.30 pmol.min-1.mm-1 and JMg2+ from 0.51 +/- 0.08 to 0.84 +/- 0.08 pmol.min-1.mm-1.JK+ remained unchanged: 3.2 +/- 1.3 versus 4.0 +/- 1.9 pmol.min-1.mm-1. Neither PDte (16.3 +/- 1.5 versus 15.9 +/- 1.4 mV) nor Rte (22.5 +/- 3.0 versus 20.3 +/- 2.6 omega cm2) were changed significantly by glucagon. However, in the post-experimental periods a significant decrease in PDte and increase in Rte were noted. In mTAL-segments (n = 9), Mg2+ and Ca2+ transports were close to zero and glucagon elicited no significant effect. The reabsorptions of Na+ and Cl-, however, were strongly stimulated: JNa+ increased from 153 +/- 17 to 226 +/- 30 pmol.min-1.mm-1 and JCl- from 151 +/- 23 to 243 +/- 30 pmol.min-1.mm-1.(ABSTRACT TRUNCATED AT 250 WORDS)
Di Stefano
A
A
Département de Biologie/CEA, CEN Saclay, Gif-sur-Yvette, France.
Wittner
M
M
Nitschke
R
R
Braitsch
R
R
Greger
R
R
Bailly
C
C
Amiel
C
C
Elalouf
J M
JM
Roinel
N
N
de Rouffignac
C
C
D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology; D001692:Biological Transport; D002412:Cations / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D005260:Female; D005934:Glucagon / Q000502:physiology*; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D008138:Loop of Henle / Q000378:metabolism*; D051379:Mice; D011677:Punctures
D002412:Cations; D002712:Chlorides; D001127:Arginine Vasopressin; D005934:Glucagon