Abstract
We previously reported that rabbit renal cortical collecting tubules can secrete bicarbonate in vitro (i.e., there can be net transport from bath to lumen, causing the concentration in the lumen to increase). Net bicarbonate secretion was observed most often when rabbits had been pretreated with NaHCO3 and were excreting alkaline urine before being killed for experiments. The purpose of the present studies was to elucidate the mechanism involved by testing the effects of ion substitutions and drugs on collecting tubules that were secreting bicarbonate. Acetazolamide inhibited net bicarbonate secretion, suggesting that the process is dependent upon carbonic anhydrase. Net bicarbonate secretion also decreased when sodium in the perfusate and bath was replaced by choline, but not when chloride was replaced by nitrate or methylsulfate. Ouabain had no significant effect. Amiloride caused net bicarbonate secretion to increase. The rate of net secretion did not correlate with transepithelial voltage. The results are compared to those in turtle urinary bladders that also secrete bicarbonate. There are no direct contradictions between the results in the two tissues, i.e., in turtle bladders acetazolamide also inhibited bicarbonate secretion and ouabain had no effect. Nevertheless, it seems unlikely that net secretion of bicarbonate by collecting tubules involves specific exchange for chloride, as has been proposed for turtle bladders, because replacement of chloride by other anions did not inhibit bicarbonate secretion by collecting tubules. It was previously shown that the collecting tubules in vitro also may absorb bicarbonate, especially when the rabbits have been treated with NH4Cl and are excreting acid urine before being killed. The effects of drugs on net bicarbonate secretion found in the present studies are compared to their previously reported effects on net bicarbonate absorption and the possibility is discussed that bicarbonate absorption and secretion are independent processes, as was previously proposed for turtle bladders.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arruda J. A., Nascimento L., Mehta P. K., Rademacher D. R., Sehy J. T., Westenfelder C., Kurtzman N. A. The critical importance of urinary concentrating ability in the generation of urinary carbon dioxide tension. J Clin Invest. 1977 Oct;60(4):922–935. doi: 10.1172/JCI108847. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baba W. I., Lant A. F., Smith A. J., Townshend M. M., Wilson G. M. Pharmacological effects in animals and normal human subjects of the diuretic amiloride hydrochloride (MK-870). Clin Pharmacol Ther. 1968 May-Jun;9(3):318–327. doi: 10.1002/cpt196893318. [DOI] [PubMed] [Google Scholar]
- Burg M. B., Green N. Function of the thick ascending limb of Henle's loop. Am J Physiol. 1973 Mar;224(3):659–668. doi: 10.1152/ajplegacy.1973.224.3.659. [DOI] [PubMed] [Google Scholar]
- Burg M. B. Perfusion of isolated renal tubules. Yale J Biol Med. 1972 Jun-Aug;45(3-4):321–326. [PMC free article] [PubMed] [Google Scholar]
- Burg M., Grantham J., Abramow M., Orloff J. Preparation and study of fragments of single rabbit nephrons. Am J Physiol. 1966 Jun;210(6):1293–1298. doi: 10.1152/ajplegacy.1966.210.6.1293. [DOI] [PubMed] [Google Scholar]
- Dietz J., Field M. Ion transport in rabbit ileal mucosa. IV. Bicarbonate secretion. Am J Physiol. 1973 Oct;225(4):858–861. doi: 10.1152/ajplegacy.1973.225.4.858. [DOI] [PubMed] [Google Scholar]
- Fitzgerrel W. W., Vanatta J. C. Excretion of HCO3- by the urinary bladder of Bufo marinus in metabolic alkalosis. Tex Rep Biol Med. 1975;33(2):269–273. [PubMed] [Google Scholar]
- Fromm D., Schwartz J. H. Ion transport across isolated antral mucosa of the rabbit. Am J Physiol. 1976 Dec;231(6):1783–1789. doi: 10.1152/ajplegacy.1976.231.6.1783. [DOI] [PubMed] [Google Scholar]
- Grantham J. J., Burg M. B. Effect of vasopressin and cyclic AMP on permeability of isolated collecting tubules. Am J Physiol. 1966 Jul;211(1):255–259. doi: 10.1152/ajplegacy.1966.211.1.255. [DOI] [PubMed] [Google Scholar]
- Grantham J. J., Kurg M. B., Obloff J. The nature of transtubular Na and K transport in isolated rabbit renal collecting tubules. J Clin Invest. 1970 Oct;49(10):1815–1826. doi: 10.1172/JCI106399. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gross J. B., Imai M., Kokko J. P. A functional comparison of the cortical collecting tubule and the distal convoluted tubule. J Clin Invest. 1975 Jun;55(6):1284–1294. doi: 10.1172/JCI108048. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Guignard J. P., Peters G. Effects of triamterene and amiloride on urinary acidification and potassium excretion in the rat. Eur J Pharmacol. 1970 May;10(2):255–267. doi: 10.1016/0014-2999(70)90281-5. [DOI] [PubMed] [Google Scholar]
- McKinney T. D., Burg M. B. Bicarbonate transport by rabbit cortical collecting tubules. Effect of acid and alkali loads in vivo on transport in vitro. J Clin Invest. 1977 Sep;60(3):766–768. doi: 10.1172/JCI108830. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McKinney T. D., Burg M. B. Biocarbonate and fluid absorption by renal proximal straight tubules. Kidney Int. 1977 Jul;12(1):1–8. doi: 10.1038/ki.1977.72. [DOI] [PubMed] [Google Scholar]
- RECTOR F. C., Jr, CARTER N. W., SELDIN D. W. THE MECHANISM OF BICARBONATE REABSORPTION IN THE PROXIMAL AND DISTAL TUBULES OF THE KIDNEY. J Clin Invest. 1965 Feb;44:278–290. doi: 10.1172/JCI105142. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schafer J. A., Andreoli T. E. Cellular constraints to diffusion. The effect of antidiuretic hormone on water flows in isolated mammalian collecting tubules. J Clin Invest. 1972 May;51(5):1264–1278. doi: 10.1172/JCI106921. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sheerin H. E., Field M. Ileal HCO3 secretion: relationship to Na and Cl transport and effect of theophylline. Am J Physiol. 1975 Apr;228(4):1065–1074. doi: 10.1152/ajplegacy.1975.228.4.1065. [DOI] [PubMed] [Google Scholar]
- Steinmetz P. R. Characteristics of hydrogen ion transport in urinary bladder of water turtle. J Clin Invest. 1967 Oct;46(10):1531–1540. doi: 10.1172/JCI105644. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stoner L. C., Burg M. B., Orloff J. Ion transport in cortical collecting tubule; effect of amiloride. Am J Physiol. 1974 Aug;227(2):453–459. doi: 10.1152/ajplegacy.1974.227.2.453. [DOI] [PubMed] [Google Scholar]
- Vieira F. L., Malnic G. Hydrogen ion secretion by rat renal cortical tubules as studied by an antimony microelectrode. Am J Physiol. 1968 Apr;214(4):710–718. doi: 10.1152/ajplegacy.1968.214.4.710. [DOI] [PubMed] [Google Scholar]
- Vurek G. G., Warnock D. G., Corsey R. Measurement of picomole amounts of carbon dioxide by calorimetry. Anal Chem. 1975 Apr;47(4):765–767. doi: 10.1021/ac60354a024. [DOI] [PubMed] [Google Scholar]
- Ziegler T. W., Fanestil D. D., Ludens J. H. Influence of transepithelial potential difference on acidification in the toad urinary bladder. Kidney Int. 1976 Oct;10(4):279–286. doi: 10.1038/ki.1976.110. [DOI] [PubMed] [Google Scholar]