Pflügers Archiv

, Volume 427, Issue 1–2, pp 151–156 | Cite as

An electrophysiological study of angiotensin II regulation of Na-HCO3 cotransport and K conductance in renal proximal tubules

II. Effect of micromolar concentrations
  • Salvatore Coppola
  • Eberhard Frömter
Transport Processes, Metabolism and Endocrinology; Kidney, Gastrointestinal Tract, and Exocrine Glands

Abstract

In the first part of our study, we described the effect of picomolar concentrations of angiotensin II (AII) on cell membrane potential (Vb) and cell pH (pHi) of isolated perfused rabbit renal proximal tubules. In the present publication we summarize respective observations with micromolar concentrations of AII. With a few exceptions nearly all experiments showed mirrorimage-like results. In the majority of the experiments 10−6 mol/l AII, when applied from the bath (but not when applied from the lumen), slightly hyperpolarized the cells by −3.4±0.3 mV (mean±SEM,n=20) and alkalinized them by up to 0.06 pH units, while the lower AII concentrations, which were applied in the previous study, depolarized and acidified. The present observations suggest that micromolar concentrations of AII inhibit basolateral Na-HCO3 cotransport. This conclusion was confirmed by a decreasingVb response to step changes of basolateral HCO3 concentration. In addition, there was a tendency of theVb response to K concentration steps to decrease, but measurements of the voltage divider ratio did not point to a significant inhibition of a basolateral K conductance. In spite of the almost perfect reciprocity of the results with 10−6 and 10−11 mol/l AII, some specific observations suggest that micromolar concentrations of AII do not simply cause mirror-image-like effects, but influence still further transport systems compared to picomolar concentrations.

Key words

Rabbit renal proximal tubule Angiotensin II Cell potential Cell pH Na-HCO3 cotransport K conductance 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Chatsudthipong V, Chan YL (1991) Inhibitory effect of angiotensin II on renal tubular transport. Am J Physiol 260:F340-F346Google Scholar
  2. 2.
    Coppola S, Frömter E (1994) An electrophysiological study of angiotensin II regulation of Na-HCO3 cotransport and K conductance in renal proximal tubules. I. Effect of picomolar concentrations. Pflügers Arch 427:143–150Google Scholar
  3. 3.
    Domingues JH, Snowdowne KW, Freudenrich CC, Brown T, Borle AB (1987) Intracellular messenger for action of angiotensin II on fluid transport in rabbit proximal tubule. Am J Physiol 252:F 423-F 428Google Scholar
  4. 4.
    Douglas JG (1987) Angiotensin receptor subtypes of the kidney cortex. Am J Physiol 253:F 1-F 7Google Scholar
  5. 5.
    Harris PJ, Young JA (1977) Dose-dependent stimulation and inhibition of proximal tubular sodium reabsorption by angiotensin II in the rat kidney. Pflügers Arch 367:295–297Google Scholar
  6. 6.
    Hoyer J, Popp R, Meyer J, Galla HJ, Gögelein H (1991) Angiotensin II, Vasopressin and GTP (γ-S) inhibit inward-rectifying K channels in porcine cerebral capillary endothelial cells. J Mernbr Biol 123:55–62Google Scholar
  7. 7.
    Jung KY, Endou H (1989) Biphasic increasing effect of angiotensin II on intracellular free calcium in isolated early proximal tubule. Biochem Biophys Res Commun 165:1221–1228Google Scholar
  8. 8.
    Liu FY, Cogan MG (1988) Angiotensin II stimulation of hydrogen ion secretion in the rat early proximal tubules. Modes of action, mechanism and kinetics. J Clin Invest 82:601–607Google Scholar
  9. 9.
    Liu FY, Cogan MG (1989) Angiotensin II stimulates early proximal bicarbonate absorption in the rat by decreasing cyclic adenosine monophosphate. J Clin Invest 84:83–91Google Scholar
  10. 10.
    Liu FY, Cogan MG (1990) Role of protein kinase C in proximal bicarbonate absorption and angiotensin II signaling. Am J Physiol 258:F 927-F 933Google Scholar
  11. 11.
    Payett DM, Dupuis G (1992) Dual regulation of the n type K channel in Jurkat T lymphocytes by protein kinase A and C. J Biol Chem 267:18 270–18 273Google Scholar
  12. 12.
    Ruiz OS, Arruda JAL (1992) Regulation of the renal NaHCO3 cotransporter by cAMP and Ca-dependent proteine kinases. Am J Physiol 262:F 560-F 565Google Scholar
  13. 13.
    Seki G, Coppola S, Frömter E (1993) The Na+-HCO3- cotransporter operates with a coupling ratio of 2HCO3 to 1Na+ in isolated rabbit renal proximal tubule. Pflügers Arch 425:409–416Google Scholar
  14. 14.
    Toro L, Amador M, Stefani E (1990) ANGII inhibits calciumactivated potassium channels from coronary smooth muscle in lipid bilayers. Am J Physiol 258:H 912-H 915Google Scholar
  15. 15.
    Wang W, Giebisch G (1991) Dual modulation of renal ATP-sensitive K channel by protein kinases A and C. Proc Natl Acad Sci USA 88:9722–9725Google Scholar

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Salvatore Coppola
    • 1
  • Eberhard Frömter
    • 1
  1. 1.Zentrum der PhysiologieKlinikum der Johann Wolfgang Goethe-UniversitätFrankfurt/MainGermany

Personalised recommendations