Glucagon inhibits urinary acidification in the rat.
The effects on urinary acidification of an acute infusion of glucagon (GLU) were studied by paired experiments in plasma-replete rats whose endogenous GLU secretion was restrained by a 0.7 ng.min-1.g body wt-1 somatostatin infusion. GLU did not affect the glomerular filtration rate in any of the plasma-replete rats studied. In 10 thyroparathyroidectomized (TPTX) rats and five intact rats subjected to hypotonic volume expansion, a low-dose (0.02 ng.min-1.g body wt-1) GLU infusion that raised the plasma GLU concentration from 302 +/- 63 to 1,010 +/- 140 pg/ml significantly increased the urinary bicarbonate excretion and decreased the urinary net acid excretion; a high-dose (0.05 ng.min-1.g body wt-1) glucagon infusion in the intact rats, that increased the plasma GLU concentration to 1,609 +/- 307 pg/ml, further enhanced the urinary bicarbonate excretion rate. In intact plasma-replete rats that were not subjected to a hypotonic volume expansion, low- and high-dose GLU infusions failed to affect the urinary bicarbonate excretion rate. Finally, no change in urinary excretion rates was noted in TPTX volume-expanded time control rats. We conclude that 1) physiological increments in plasma GLU concentration decrease urinary acidification by affecting the tubular H+/bicarbonate transport; 2) the bicarbonaturic effect of GLU may be blunted by the renal effects of high circulating antidiuretic hormone levels, or may be facilitated in an undetermined manner by hypotonic volume expansion.
Delahousse
M
M
Laboratoire de Physiologie et Physiopathologie Rénale et Electrolytique, Université Paris VII, Hôpital Louis Mourier, Colombes, France.
Mercier
O
O
Bichara
M
M
Paillard
M
M
Leviel
F
F
Assan
R
R
D000818:Animals; D001639:Bicarbonates / Q000652:urine; D004573:Electrolytes / Q000652:urine; D005919:Glomerular Filtration Rate / Q000187:drug effects; D005934:Glucagon / Q000097:blood / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D010280:Parathyroid Glands / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013965:Thyroidectomy; D014556:Urine
D001639:Bicarbonates; D004573:Electrolytes; D005934:Glucagon