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α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux

Publication ,  Journal Article
Strittmatter, WJ; Davis, JN; Lefkowitz, RJ
Published in: Journal of Biological Chemistry
December 1, 1977

α-Adrenergic stimulation of parotid acinar cells elicits a release of intracellular K+. The binding of [3H]dihydroergocryptine was used to characterize the α-adrenergic receptor binding sites in both parotid membranes and dissociated parotid acinar cells. [3H]Dihydroergocryptine binds rapidly to both the membranes and dissociated cells. The association rate constant in membranes was 1.7 x 107 liters mol-1 min-1 at 20°. In cells [3H]dihydroergocryptine binding reached equilibrium within 10 min. [3H]Dihydroergocryptine binding was saturable in membranes with 29.7 fmol bound/mg of protein and a K(D) of 10.5 nM. [3H]Dihydroergocryptine binding to cells rendered hypoxic, or frozen and thawed, was saturable with approximately 15,000 sites/cell. By contrast, binding to incubated, oxygenated cells did not saturate at concentrations of [3H]dihydroergocryptine up to 20 nM. [3H]Dihydroergocryptine binding closely correlated with measurements of K+ release. The ability of eight adrenergic agents to displace [3H]dihydroergocryptine correlated (r = 0.98) with their ability to stimulate or block K+ release and had the typical potency series expected for an α-adrenergic receptor (epinephrine > norepinephrine much greater than isoproterenol; (-)-epinephrine > (+)-epinephrine; (-)-norepinephrine > (+)-norepinephrine). K+ efflux generated by α-adrenergic stimulation reached maximum at 30 to 60 s. K+ was then taken up by the cells with a half-time of 4 min. This uptake could be blocked by ouabain. The maximum release of K+ by 10-3M epinephrine in the presence of 10-3M ouabain was 2.3 μg of K+/106 cells. Since each cell possesses 15,000 binding sites, 2.3 x 106 molecules of K+ are released per binding site. If 60 s are required for release, 4 x 104 molecules of K+/binding site/s are released.

Duke Scholars

Published In

Journal of Biological Chemistry

ISSN

0021-9258

Publication Date

December 1, 1977

Volume

252

Issue

15

Start / End Page

5472 / 5477

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 34 Chemical sciences
  • 32 Biomedical and clinical sciences
  • 31 Biological sciences
  • 11 Medical and Health Sciences
  • 06 Biological Sciences
  • 03 Chemical Sciences
 

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Strittmatter, W. J., Davis, J. N., & Lefkowitz, R. J. (1977). α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux. Journal of Biological Chemistry, 252(15), 5472–5477.
Strittmatter, W. J., J. N. Davis, and R. J. Lefkowitz. “α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux.” Journal of Biological Chemistry 252, no. 15 (December 1, 1977): 5472–77.
Strittmatter WJ, Davis JN, Lefkowitz RJ. α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux. Journal of Biological Chemistry. 1977 Dec 1;252(15):5472–7.
Strittmatter, W. J., et al. “α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux.” Journal of Biological Chemistry, vol. 252, no. 15, Dec. 1977, pp. 5472–77.
Strittmatter WJ, Davis JN, Lefkowitz RJ. α Adrenergic receptors in rat parotid cells. I. Correlation of [3H] dihydroergocryptine binding and catecholamine stimulated potassium efflux. Journal of Biological Chemistry. 1977 Dec 1;252(15):5472–5477.

Published In

Journal of Biological Chemistry

ISSN

0021-9258

Publication Date

December 1, 1977

Volume

252

Issue

15

Start / End Page

5472 / 5477

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 34 Chemical sciences
  • 32 Biomedical and clinical sciences
  • 31 Biological sciences
  • 11 Medical and Health Sciences
  • 06 Biological Sciences
  • 03 Chemical Sciences