Effects of glucagon on H(+)-HCO3- transport in Henle's loop, distal tubule, and collecting ducts in the rat.

Paired micropuncture experiments were carried out in somatostatin-infused volume-expanded rats to examine the effects of a glucagon infusion (0.05 ng.min-1.g body wt-1) on urinary acidification and tubular handling of bicarbonate. Whole kidney and single-nephron glomerular filtration rate were not affected by glucagon. In thyroparathyroidectomized (TPTX) rats, glucagon inhibited the reabsorption of total CO2 in Henle's loop. In intact animals, however, the latter effect was not observed. In the distal tubule accessible to micropuncture, net total CO2 absorption was observed during volume expansion plus somatostatin infusion, which reversed to net total CO2 secretion during glucagon infusion in Wistar rats; thus the late distal delivery of total CO2 increased almost 80%. Marked inhibition of urinary acidification occurred in all animals as evidenced by a rise in urine pH and bicarbonate excretion. Conversely, a somatostatin infusion, which decreased the plasma glucagon concentration, stimulated net total C...